sci.electronics.repair - 25 new messages in 8 topics - digest

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sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: Tektronix 7603
http://groups.google.com/group/sci.electronics.repair/t/efb86f5dc14fc24b?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 30 2011 10:18 pm
From: Jeff Urban

"This is the reason so many have left the group for greener pastures.
They got tired of whiny jerks like you. "

You know a hell of alot about me out of one post. I am a whiney
jerk ?

Interesting assessment. You know what, I don't need that or any other
Tektroniks, or any other type of bullshit equipment like that. Gimme
my P2P, PC and good soundcard. I'll throw the fucking Tektronix out on
the treelawn after a treatment with the hammer. No problem.

Was that your goal ? Hope so, so you can be proud of yourself. And,
this little self help group here, help your self. Yuo DON'T want me to
lift a finger, now.

Tell Jim Yanik I am sorry, I'll see him at the NRA meeting. The rest
of you, go fuck yourselves.

Fukt if I have to sign this, you knopw who the fuck I am.

==============================================================================
TOPIC: Why do some manufacturers wrap the electrolytic capacitor that gets the
hottest in a switching power supply in shrink wrap?
http://groups.google.com/group/sci.electronics.repair/t/2a675f3c64fd62cc?hl=en
==============================================================================

== 1 of 4 ==
Date: Wed, Aug 31 2011 12:21 am
From: "N_Cook"

Chuck <chuckh@deja.net> wrote in message
news:3giq5793mdtgi0f6ssmf2pp79bn9ukbeuv@4ax.com...
> Extron has been doing this for years and of course it is the first
> part to fail in their units. Smart Technologies Sympodium power
> supplies, that they have contract built in China, fail in a year or so
> for the same reason. Technicians and electronic engineers at my work
> place can't think of a rational reason why these manufacturers do
> this. This is pro gear where reliability is a great concern so it
> doesn't seem to be planned failure mode. Thanks. Chuck

Someone's idea of a black body radiator?

== 2 of 4 ==
Date: Wed, Aug 31 2011 4:19 am
From: "Wild_Bill"

Elevated internal current leakage in electrolytic caps will heat them up.
The 'lytics with higher than normal internal leakage are the ones that
troubleshooters will miss, if the only tester they have is an ESR meter.

Leakage tests aren't performed in-circuit, therefore it's a good practice to
test new 'lytics when they're received and again before installing them if
they've been stored for long periods.

I don't do much repair work anymore, but had a habit of checking ESR (Value
and DA) and Leakage when new caps were received, and some new 'lytics would
fail Leakage tests occasionally, quickly getting very warm at their rated
voltage.

One of the most often repeated repair tips is to look for bulged tops and/or
signs of external leakage wrt electrolytic caps.
Generally, ESR checks are also advised, but electrolytic caps have other
faults and failures which rarely get mentioned.

--
Cheers,
WB
.............

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:ee1r57hh5mtuv1gjhuk4iq9cg0negjm7tm@4ax.com...
>
> Probably to keep you from touching the can, which is probably
> electrically hot. The life you save may be your own.
>
> Electrolytic caps do not normally get hot. There is a temperature
> rise equal to the ripple current times the square of the ESR
> (equivlent series resistance). If the ESR is too high, usually due to
> underspecifying the voltage rating or capacitor type, it will get
> warm. There are derating curves for capacitors at various
> temperatures. There are also lifetime prediction calculators which
> include the operating temperature.
>
> If you're shopping for a conspiracy theory, I guess the capacitors are
> badly specified or picking up heat from adjacent heat dissipating
> devices. A nearby resistor or heat sunk xsistor will heat up a cap
> quite nicely. The shrink tube will have little effect on the cap
> temperature. Black absorbs more heat, so it might be slightly warmer
> from nearby radiation. At best, maybe a degree or two.
>
> Pro audio is the same as consumer audio, except for the price tag and
> the hype.
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831-336-2558
> # http://802.11junk.com jeffl@cruzio.com
> # http://www.LearnByDestroying.com AE6KS

== 3 of 4 ==
Date: Wed, Aug 31 2011 8:53 am
From: chuck

On Tue, 30 Aug 2011 15:31:52 -0700, dplatt@radagast.org (Dave Platt)
wrote:

>In article <3giq5793mdtgi0f6ssmf2pp79bn9ukbeuv@4ax.com>,
>Chuck <chuckh@deja.net> wrote:
>
>>Extron has been doing this for years and of course it is the first
>>part to fail in their units. Smart Technologies Sympodium power
>>supplies, that they have contract built in China, fail in a year or so
>>for the same reason. Technicians and electronic engineers at my work
>>place can't think of a rational reason why these manufacturers do
>>this. This is pro gear where reliability is a great concern so it
>>doesn't seem to be planned failure mode. Thanks. Chuck
>
>I've heard it said:
>
> "When the question is `Why is company X doing seemingly irrational
> thing Y in their product design?', the answer is most commonly
> `Money',"
>
>Electrolytic capacitors are normally shipped, by their manufacturers,
>in a plastic insulating jacket. It's the common method used to
>insulate the cases against accidental shorts, and to allow convenient
>marking (no separate marking process is required during manufacture,
>since the markings are manufactured into the plastic).
>
>Almost all "commodity" 'lytics are of this sort. If you want caps
>with another sort of jacketing (even "none at all") you'd probably
>have to special-order them, there would be far fewer possible sources,
>and the cost per piece would end up being significantly higher.
>
>There's immense price-pressure and competition in the electronics
>manufacturing business, even for "pro gear". A matter of a few cents
>per power supply can make the difference between a contract
>manufacturer getting, or losing the bid. The manufacturers thus have
>a *very* strong incentive to use standard parts... and, in fact, the
>cheapest and lowest-rated ones which will allow the final supply to
>pass its paper requirements (which may not include long-life survival
>tests).
>
>I've heard that it's quite common for overseas contract manufacturers
>to covertly "down-rate" parts, after they win a bid... that is, the
>specific caps and resistors and etc. that they stuff into the
>production lots, may not be the same as the ones they stuffed into the
>samples that they submitted. Unless you stand over 'em with a club,
>and do a strict verification of what you receive, you may get
>lower-quality subsystems than you had been originally offered. You
>might even get counterfeit parts (e.g. cheap 85-degree-C caps, which
>have been falsely labeled as 105-degree-C, or generic caps falsely
>marked to indicate low-ESR, high-ripple-current ruggedness).
>
>If the final system survives to the end of its warranty period, many
>companies seem to feel that this is Plenty Good Enough, and brings in
>additional revenue for repairs and replacements.

To clarify, this isn't the standard cap wrapping from the factory.
This is a thick piece of shrink tubing that is put over the
capacitor's normal wrapping and then shunk tightly around the cap like
a blanket. Chuck

== 4 of 4 ==
Date: Wed, Aug 31 2011 12:55 pm
From: John Robertson

Chuck wrote:
> Extron has been doing this for years and of course it is the first
> part to fail in their units. Smart Technologies Sympodium power
> supplies, that they have contract built in China, fail in a year or so
> for the same reason. Technicians and electronic engineers at my work
> place can't think of a rational reason why these manufacturers do
> this. This is pro gear where reliability is a great concern so it
> doesn't seem to be planned failure mode. Thanks. Chuck

What happens when you complain to Extron? And why - if they don't fix
the problem - do you keep dealing with Extron or Smart Technologies?

A company has to respond properly to design flaws or you change suppliers.

Seems simple to me.

If management says the items are cheaper then point out the downstream
repair costs are more than the few bucks it would cost to get a better
supply and thus a better reputation for reliability in the real world
(as opposed to the costing world).

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

==============================================================================
TOPIC: Yellow Glue strikes again
http://groups.google.com/group/sci.electronics.repair/t/9d8bded3db582b06?hl=en
==============================================================================

== 1 of 8 ==
Date: Wed, Aug 31 2011 12:38 am
From: "Gareth Magennis"

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:9c5fb1FhtrU1@mid.individual.net...
>
> ** I had hoped that the dreaded Yellow Glue peril had gone away - but it
> is still with us.
>
> Most of you will have seen it holding parts down to PCBs on Asian made
> equipment and many of those will have seen what happens if the parts
> involved get hot.
>
> The example on my bench is the SMPS from an Alesis powered monitor ( M1
> Active, Chinese made) ) which has blown up big time because of the damn
> Yellow Glue used to secure a ferrite toroidal coil. All the glue used had
> gone brown or back ( ie carbonised ) on this coil and arced across nearby
> tracks taking out the main switching MOSFET, its drive IC and associated
> transistors, high speed diodes and even the AC bridge rectifier diodes.
>
> The toroidal coil had to be un-wound, cleaned up and re-wound. The same
> glue was attacking parts elsewhere on the board too ( it corrodes copper)
> and had to be laboriously scraped off.
>
> Are the dickheads who squirt this horrible goop all over PCBs NEVER
> going to wake up ??
>
>
>
> ..... Phil
>
>
>

I had an M1 with exactly the same problem. Conductive gak all over the
place, very messy, but fortunately didn't blow anything up.

Gareth.

== 2 of 8 ==
Date: Wed, Aug 31 2011 1:03 am
From: "N_Cook"

Jeff Liebermann <jeffl@cruzio.com> wrote in message
news:835r57pbgh3vv5jcj855s221u912u1fu0c@4ax.com...
> On Wed, 31 Aug 2011 11:50:53 +1000, "Phil Allison" <phil_a@tpg.com.au>
> wrote:
>
> >** I've always wanted to know just WFT it really is !!
>
> This description seems to fit:
>
<http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant
_flame_retardant.html>
> "One component solvent resistant flame-retardant waterproof yellow
> fixing adhesive glue for electronic components"
>
> Note the photos. Is that it? I'll do some more Googling later. Gotta
> seperate my customers from their money.
>
>
> --
> # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
> # 831-336-2558
> # http://802.11junk.com jeffl@cruzio.com
> # http://www.LearnByDestroying.com AE6KS

That "Japanese" brown gloop made a comeback also, from my trepair briefs

Sherwood RD6106 tuner amp, may 2000 from front panel moulding
I though that hygroscopic brown glue stuff went out in the 70s. Used to
secure 12.288M crystal for the digital interface processor YSS912C-F , was
around its
pin and had rusted through at the epoxy bond.

== 3 of 8 ==
Date: Wed, Aug 31 2011 2:48 am
From: "N_Cook"

If the brown hard-glue is the same as the yellow stuff. Is the progress to
destruction that it becomes hygroscopic going from yellow to brown and so
becomes conductive for CMOSSy sort of stuff but if HV around then conducts
enough to then carbonise and become ever more conductive?

== 4 of 8 ==
Date: Wed, Aug 31 2011 9:09 am
From: Cydrome Leader

Phil Allison <phil_a@tpg.com.au> wrote:
>
> "Jeff Liebermann"
>>>
>>>> Is that hot melt glue or something else?
>>>
>>>** So you do no repair work at all ?
>>
>> Just answer the question.
>
>
> ** You are not a repair tech, or you would have seen it many times.
>
> Always Asian made gear, from about the 1980s onwards.
>
> TV sets, VCRs, SMPSs anything where the maker felt it was a good idea to
> glue things to the PCB.
>
> Do a Google search on this NG under " yellow glue".

that stuff is pure shit.

== 5 of 8 ==
Date: Wed, Aug 31 2011 10:15 am
From: chuck

On Wed, 31 Aug 2011 10:59:58 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>
>** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
>still with us.
>
>Most of you will have seen it holding parts down to PCBs on Asian made
>equipment and many of those will have seen what happens if the parts
>involved get hot.
>
>The example on my bench is the SMPS from an Alesis powered monitor ( M1
>Active, Chinese made) ) which has blown up big time because of the damn
>Yellow Glue used to secure a ferrite toroidal coil. All the glue used had
>gone brown or back ( ie carbonised ) on this coil and arced across nearby
>tracks taking out the main switching MOSFET, its drive IC and associated
>transistors, high speed diodes and even the AC bridge rectifier diodes.
>
>The toroidal coil had to be un-wound, cleaned up and re-wound. The same glue
>was attacking parts elsewhere on the board too ( it corrodes copper) and had
>to be laboriously scraped off.
>
>Are the dickheads who squirt this horrible goop all over PCBs NEVER going
>to wake up ??
>
>
>
>..... Phil
>
>

The rumor among techs in the U.S. when this stuff first showed up was
it was originally manufactured by Sony and it was known as "Sony
glue". Don't know if there was any truth to this or not. As Phil
said, it was in widespread use, for example: Mitsubishi televisions,
Adcom preamps and tuners, Yamaha receivers, Extron products and many
others which I can't recall off the top of my head. Chuck

== 6 of 8 ==
Date: Wed, Aug 31 2011 12:04 pm
From: "Gareth Magennis"

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:j3kvss$l47$1@dont-email.me...
> If the brown hard-glue is the same as the yellow stuff. Is the progress to
> destruction that it becomes hygroscopic going from yellow to brown and so
> becomes conductive for CMOSSy sort of stuff but if HV around then conducts
> enough to then carbonise and become ever more conductive?
>
>

The brown brittle stuff I scraped off the M1 PCB was around the low voltage
audio pre-amp and Power Amp IC.
It was conductive enough to render the circuit useless, no HV necessary.

Gareth.

== 7 of 8 ==
Date: Wed, Aug 31 2011 12:05 pm
From: Jim Yanik

"Gareth Magennis" <sound.service@btconnect.com> wrote in
news:Ixl7q.182412$2I6.127551@newsfe27.ams2:

>
>
> "Phil Allison" <phil_a@tpg.com.au> wrote in message
> news:9c5fb1FhtrU1@mid.individual.net...
>>
>> ** I had hoped that the dreaded Yellow Glue peril had gone away - but
>> it is still with us.
>>
>> Most of you will have seen it holding parts down to PCBs on Asian
>> made equipment and many of those will have seen what happens if the
>> parts involved get hot.
>>
>> The example on my bench is the SMPS from an Alesis powered monitor (
>> M1 Active, Chinese made) ) which has blown up big time because of the
>> damn Yellow Glue used to secure a ferrite toroidal coil. All the
>> glue used had gone brown or back ( ie carbonised ) on this coil and
>> arced across nearby tracks taking out the main switching MOSFET, its
>> drive IC and associated transistors, high speed diodes and even the
>> AC bridge rectifier diodes.
>>
>> The toroidal coil had to be un-wound, cleaned up and re-wound. The
>> same glue was attacking parts elsewhere on the board too ( it
>> corrodes copper) and had to be laboriously scraped off.
>>
>> Are the dickheads who squirt this horrible goop all over PCBs NEVER
>> going to wake up ??
>>
>>
>>
>> ..... Phil
>>

the manufacturers probably don't get the products back(due to their age)
for failure analysis,and thus are unaware it happens.
No "closed-loop action process".

OR,it's planned "obsolesence".
or both. ;-)
>>
>>
>
>
> I had an M1 with exactly the same problem. Conductive gak all over
> the place, very messy, but fortunately didn't blow anything up.
>
>
>
> Gareth.
>
>

--
Jim Yanik
jyanik
at
localnet
dot com

== 8 of 8 ==
Date: Wed, Aug 31 2011 1:38 pm
From: "Trevor Wilson"

Jeff Liebermann wrote:
> On Wed, 31 Aug 2011 10:59:58 +1000, "Phil Allison" <phil_a@tpg.com.au>
> wrote:
>
>> ** I had hoped that the dreaded Yellow Glue peril had gone away -
>> but it is still with us.
>>
>> Most of you will have seen it holding parts down to PCBs on Asian
>> made equipment and many of those will have seen what happens if the
>> parts involved get hot.
>
> Is that hot melt glue or something else?
> Hot melt should, umm... melt, not burn.

**No. It is a type of contact adhesive. It is still in widespread use, for
reasons I don't understand. Some, more enlightened manufacturers, use a
silicon type glue, which has a much higher burning temperature.

--
Trevor Wilson
www.rageaudio.com.au

==============================================================================
TOPIC: slider pot mystery
http://groups.google.com/group/sci.electronics.repair/t/8f3b96bc9d641bc7?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Aug 31 2011 12:40 am
From: "N_Cook"

mono slider but 6 pins plus frame anchors
3 of the pins are the pot function , 2 one end and one the other. The other
2 plus 1 are dummies. Inside, the slider is split into 2 . One wiper doing
the mono wiper action and the other vainly wiping along 2 x 2.5K resistive
tracks not connected to the pins or anywhere , why? Just for feel is the
only reason I can come up with along with standardising on one outer body
and pinning manufacturing line (and for to confuse repairmen)

== 2 of 2 ==
Date: Wed, Aug 31 2011 2:29 am
From: "N_Cook"

10K slider pot , Chinese, marked Soundwell , N B103, 738B103

==============================================================================
TOPIC: Motor start/stop switch with integrated mini contactor?
http://groups.google.com/group/sci.electronics.repair/t/13b233689d902984?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Aug 31 2011 2:37 am
From: The Ghost In The Machine

On Aug 30, 9:26 pm, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:
> On Tue, 30 Aug 2011 18:18:28 -0700 (PDT), The Ghost In The Machine
>
>
>
>
>
> <proteus...@gmail.com> wrote:
> >On Aug 30, 4:03 pm, "k...@att.bizzzzzzzzzzzz"
> ><k...@att.bizzzzzzzzzzzz> wrote:
> >> On Tue, 30 Aug 2011 12:18:02 -0700, DaveC <inva...@invalid.net> wrote:
> >> >The only Telemecanique products I've been able to find are full-size magnetic
> >> >starters (contactors).
>
> >> Ignore the troll.
>
> >> >I'm looking for a manual start/stop switch with 2-pole contactor built-in.
> >> >Pressing the start button manually closes the contacts and energizes a coil,
> >> >which holds the contacts closed. Power fail opens the contacts.
>
> >> >Small (micro!) is what I'm looking for. No larger than the size of a
> >> >start/stop switch without contactor.
>
> >> These are sometimes called "magnetic start switches" and are commonly found on
> >> larger woodworking tools. I don't know if they're small enough for you but:http://www.grizzly.com/search/search.aspx?q=power%20switch
>
> >........SHUT UP ASS DROOL.......I OWED YOU THAT!
> >AS FOR A P/N DAVE I DO NOT WORK FOR THEM...CONTACT THE CO's I
> >PROVIDED...THEY COME HIGHLY RECOMMENED FOR SWITCHES ETC.
> >WHATS NEXT?
> > COME OVER & INSTALL IT? BOOWAHAHAHAHA, NO WAY JOSÈ!
> >I AM A GHOST AND DO NOT DO MANUAL LABOR, BUT MAYBE KRAWFISHRW IS
> >WILLING TO COMPLETE THE JOB FOR YOU.
> > ASK HIS SQUALID ASS TO HELP YOU GET IT & HELP US KEEP THE INTERNET
> >FOOL FREE, ITS A GOOD COMBO.
> >ANYTIME OF THE VIRTUAL NIGHT OR DAY.
> >++BEST WISHES++
>
> At least DaveC now knows what you are.
>
> >PATECUM
>
> Still eating that stuff Queerjano.
>
> >TGITM
>
> I told you a long time ago, Queerjano, penicillin will do wonders for that.
WHAT A GAY LITTLE TWIT YOU ARE....STILL FANTASIZING I'M MR. QUIJANO?
I'M GOING TO TELL HIS BENEFACTOR ABOUT YOU.
MAYBE HE'LL GIVE YOU THE ANAL REAMING YOU DESIRE, YOU QUEER.
I BET YOU HANG AROUND THESE GROUPS LUSTING FOR COCK, EVER SINCE YOUR
DADDY LEFT YOU.
YOU SAP......QUIT STAINING YOUR PANTS BOTTOM FREAK!
YOU'RE DISGUSTING WILLAMINA.
PATECUM
TGITM

==============================================================================
TOPIC: OT: Tek 465
http://groups.google.com/group/sci.electronics.repair/t/b9f473fde6856891?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Aug 31 2011 4:49 am
From: josephkk

On Sat, 27 Aug 2011 22:46:42 -0500, Jim Yanik <jyanik@abuse.gov> wrote:

>"Mark Zacharias" <mark_zacharias@labolgcbs.net> wrote in
>news:4e59a0f2$0$2742$a8266bb1@newsreader.readnews.com:
>
>
>>
>> I thought about someone maybe getting all worked up about posting
>> something for sale here, but I figured the guys who know me wouldn't
>> care and anyone else, well, you get the idea...
>
>IMO,if a regular is selling an -occasional- item,no problem posted it
>here,just put FS: in the header.
>
>>
>> As far as the 2246 breaking, that's why I'm keeping my B&K 100mHz, as
>> a backup.
>
>Good idea.
>
>>
>> Tek is the Harley Davidson of oscilloscopes, after all.
>>
>> Mark Z.
>>
>>
>
>No,TEK -USED to be- the Harley Davidson of scopes.

Seeing what HD has become in motorcycles perhaps the analogy is still apt.

?-)

==============================================================================
TOPIC: CCFL & Inverter problem
http://groups.google.com/group/sci.electronics.repair/t/0bf30d8181a6a59c?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Aug 31 2011 8:52 am
From: benitos

On Aug 23, 1:42 pm, PlainB...@yawhoo.com wrote:
> On Mon, 22 Aug 2011 14:19:37 -0700 (PDT), benitos
>
>
>
>
>
> <bentech2...@gmail.com> wrote:
> >On 22 août, 15:28, PlainB...@yawhoo.com wrote:
> >> On Mon, 22 Aug 2011 08:37:16 -0700 (PDT), benitos
>
> >> <bentech2...@gmail.com> wrote:
> >> >Hi ,
>
> >> >Have a Toshiba Satellite laptop with a "no display" symptom.
>
> >> >After checking it, i can notice a very dim picture , the CCFL doesn't
> >> >lit.
>
> >> >After opening it , I found that the inverter had a fuse open .
>
> >> >Replace the fuse but after , the computer did not power up.
>
> >> >There was a short on the inverter boards so I replaced it with the
> >> >same model.
>
> >> >Now , the computer boots up , CCFL lit for a few seconds but shuts
> >> >down after.
>
> >> >Is is possible the the CCFL is bad also ?
>
> >> >Thanks for your help...
>
> >> It's possible. When the image first appears, is there a pinkish hue?
> >> Also, inspect the wires from the inverter to the CCFL carefully.
>
> >> PlainBill- Masquer le texte des messages précédents -
>
> >> - Afficher le texte des messages précédents -
>
> >Model is P200-MB1
>
> >Only half of the CCFL lit (kind of pink) and shuts down.
>
> That indicates the tube is old, and dying. It gets a pinkish tint
> and the current rises. Replace the tube and you will have a good
> display.
>
> PlainBill- Hide quoted text -
>
> - Show quoted text -

Hi , changed the INVERTER and CCFL and samething. Tube lit only half
and shuts down after a few seconds...

Any clue ?

==============================================================================
TOPIC: Contactor coil: 50 Hz vs. 60 Hz
http://groups.google.com/group/sci.electronics.repair/t/0d1a06068779ce43?hl=en
==============================================================================

== 1 of 7 ==
Date: Wed, Aug 31 2011 9:06 am
From: NT

On Aug 30, 4:35 pm, "petrus bitbyter" <petrus.bitby...@hotmail.com>
wrote:
> "NT" <meow2...@care2.com> schreef in berichtnews:9eae9570-949f-4798-84c2-74062c8df2b1@j1g2000yqn.googlegroups.com...
> On Aug 29, 7:03 pm, John Fields <jfie...@austininstruments.com> wrote:
>
>
>
> > On Mon, 29 Aug 2011 07:28:53 -0700 (PDT), NT <meow2...@care2.com>
> > wrote:
>
> > >On Aug 29, 3:03 pm, John Fields <jfie...@austininstruments.com> wrote:
> > >> On Sun, 28 Aug 2011 23:21:56 -0700, DaveC <inva...@invalid.net> wrote:
> > >> >I may be able to obtain a very small 2-pole 240 vac contactor I need
> > >> >rated
> > >> >for 50 Hz only.
>
> > >> >If I install it in N. America, what's the implication? Is the hold-in
> > >> >magnetism less than if it were 60 Hz? Just noisy?
>
> > >> >Please don't ask or suggest other sources. This is a very specific
> > >> >device and
> > >> >I've not been able to locate other than this.
>
> > >> Not knowing the specifics about the coil makes predicting what will
> > >> happen at 60Hz difficult.
>
> > >> However, assuming that the inductive reactance and resistance of the
> > >> coil will remain constant at 50 and 60Hz means that the impedance of
> > >> the coil at 60Hz will be 1.2 times (60Hz/50Hz) what it is at 50Hz.
>
> > >no, only the L component of the impedance will be 1.2 times as high.
>
> > ---
> > Well, that's true, so let's just see how far off I was, by using a
> > real-world example.
>
> > I have an old P&B MR5A here with a 240V 50/60Hz coil.
>
> > The coil has a resistance of 4800 ohms, and an open inductance of 14.5
> > henrys, so it has an impedance of 6616 ohms at 50 Hz, and 7270 ohms at
> > 60 Hz.
>
> > 7270 - 6616 = 1.1, so my error was 1 part in 11, or a little less than
> > 10%
>
> > I can live with that.
> > ---
>
> > >> Consequently, the current in the coil at 60Hz will be about 83% of
> > >> what it is at 50Hz.
>
> > >> If that turns out to be a problem, a higher drive voltage could be
> > >> used in order to increase the current, namely 1.2 times 240V; 288V.
>
> > >> That could easily be accomplished using a transformer to boost the
> > >> 240V mains to 288V, like this: (View with a fixed pitch font.)
>
> > >> 240AC>-----+--+
> > >> | |
> > >> oP||S
> > >> R||E
> > >> I||Co
> > >> | |
> > >> | +-----> \
> > >> | > 288AC TO COIL
> > >> 240AC>-----+--------> /
>
> > >> The transformer would need a 240V primary, a 48V secondary, and a VA
> > >> rating greater than or equal to the contactor coil's rating.
>
> > >these are the kind of 'solutions' that happen when people dont put the
> > >relevant numbers to things.
>
> > Well, your tone is certainly insulting, while the solution remains
> > valid, but since the voltage into the coil will only be 11% low, the
> > transformer secondary will only have to supply 26V instead of 48.
>
> > In reality, 24V will be fine.
>
> |
> | The relay has a voltage margin of around 50%, the mains supply wont
> | vary more than 10%, so the transformer is of no use.
> |
> |
> |NT
> |
>
> "The relay has a voltage margin of around 50%" How do you know? FAIK the op
> did not supply this numbers.
>
> petrus bitbyter

experience with various relays

== 2 of 7 ==
Date: Wed, Aug 31 2011 9:38 am
From: NT

On Aug 31, 1:36 am, John Fields <jfie...@austininstruments.com> wrote:
> On Tue, 30 Aug 2011 05:11:20 -0700 (PDT), NT <meow2...@care2.com>
> wrote:
> >On Aug 30, 12:39 pm, John Fields <jfie...@austininstruments.com>
> >wrote:
> >> On Mon, 29 Aug 2011 07:25:23 -0700 (PDT), NT <meow2...@care2.com>
> >> wrote:
>
> >> >IME relays pull in at in the region of half rated voltage, and dc
> >> >ratings are typically about half the voltage of the ac rating, which
> >> >gives an idea of how much current is determined by L and how much by
> >> >R.
>
> >> ---
> >> IME, most relays (with either AC or DC coils) are guaranteed to pull
> >> in at about 80% of their rated coil voltage, so I'm at a loss trying
> >> to understand what you meant by: "dc ratings are typically about half
> >> of the ac rating."
>
> >> Can you elaborate, please?
>
> >When relays have dual ratings for ac and dc, its normal for the dc
> >voltage rating to be half the ac voltage rating.
>
> >> >Running your relay on 220v 60Hz it will work fine.
>
> >> Knowing nothing about the contactor, other than that it's specified to
> >> energize when 240V 50Hz is placed across the coil, your imprimatur is
> >> premature.
>
> >I really dont agree. I do know the basics about relays, and one
> >normally finds that pull-in occurs at around 50% rated voltage. The OP
> >is welcome to test theirs to see if it behaves the usual way.
>
> >> >Contact closing speed will be slightly slower. Margin will be reduced,
> >> >but its only being reduced from enormous to slightly less enormous,
> >> >so its a non-issue except in very unusual situations.
>
> >> It seems you've forgotten that when the armature makes, and the
> >> magnetic circuit is closed, the inductance of the coil will rise.
>
> >I dont know why you think I've forgotten it. What's relevant here is
> >inductance in the closed position.
>
> I disagree.
>
> Since the relay is open when power is applied to the coil, it's the
> open inductance (and the resistance, of course) which will determine
> how much current will flow through the coil, that current being what
> generates the magnetic field to start the armature on its way.

yup

> Then when the relay closes, the closed inductance comes into play and
> holds the armature in place until the current through the coil is
> reduced to a point where the armature's return spring overcomes the
> weakened magnetic field, allowing the armature to open.

yes. I guess in theory both matter, one determines closing behaviour,
the other ensures the relay doesnt overheat. In practice though the
margins are very large, and its normal to simply fix holding current
to suit the relay, and not worry about closing current, which will be
so close as to make no real world difference in all but exceptional
circumstances. But yes, we can consider both if need be.

> >> Such being the case, the current in it will diminish,
>
> >true with all relays under all ac conditions. Theyre designed to work
> >that way.
>
> >> reducing the
> >> hold on the armature and making the contacts more likely to chatter.
>
> >No, its exactly how theyre designed to operate.
>
> >> >The vibration tolerance of
> >> >the contacts will be little affected in practice; if your environment
> >> >is harsh enough to shake the relay contact open, then you've got
> >> >bigger worries than contacts crackling.
> >> >If instead you meant you would use it on 110v 60Hz, then dont. But you
> >> >could use diodes to get a higher dc voltage and use that.
>
> >> Interesting conjecture.
>
> >Where's the conjecture? I get the feeling you could do with bringing
> >your skills up to speed on relays.
>
> ---
> Perhaps.
> ---
>
> >> Something like this?
>
> >> +-----+
> >> 120AC>--|~ +|----+
> >> | | |
> >> | | [COIL]
> >> | | |
> >> 120AC>--|~ -|----+
> >> +-----+
>
> >That would work.
>
> Not in all cases, certainly.

I'd like to see you find one single electromechanical relay that wont
work for.

> >> Since the coil has an impedance of about 6600 ohms at 50Hz, then the
> >> current through it will be:
>
> >> E 240V
> >> I = --- = ------- = 0.036A = 36mA
> >> Z 6600R
>
> >> Then, since the coil has a resistance of 4800 ohms, the DC voltage
> >> across it required to force 36mA through it would be:
>
> >> E = IR = 0.036A * 4800R ~ 174V.
>
> >You're not saying where you got those figures from.
>
> ---
> The P&B MR5A I talked about in an earlier post, which has a 240V
> 50/60Hz coil, a coil resistance of 4800 ohms, an impedance of ~ 6600
> ohms at 50 Hz, an open inductance of 14.5 henrys, and a closed
> inductance of 16 henrys

> >Typically dc rating is half ac rating.
>
> But I don't think "typical" is what we're after since we want
> something that will _always_ work.

This 2:1 ratio normally is good for relays, and the OP can check his
to see if it conforms to that. If it does, the thing will always work
when subject to this formula.

FWIW, when ac is applied you get puling force plus vibration. With dc
there is no vibration component when its closed, so less holding
current is needed. How much less I've really no idea.

Some relays are fast movers capable of 100s of Hz, some are slow. Ac
relays can always work on dc, but dc ones often dont work ok on ac.

> Since current is what's doing the work, my real-world example shows
> that 240V 50 Hz RMS impressed across a load with an impedance of 6600
> ohms will force 36mA RMS of current through the load.
>
> Then, since it's current that's doing the work, 36mA of DC through the
> coil should accomplish the same thing.
> ---
>
> >> The peak voltage out of the bridge would be:
>
> >> E = RMS * sqrt(2) = 120 * 1.414 ~ 170V.
>
> >> Pretty close, but at 120Hz, the reactance of the coil would increase,
> >> limiting the current to something less than the 36mA needed to close
> >> the armature.
>
> >The effect of the relay's inductance, when run off a BR, is simply to
> >smooth the current flow somewhat.
>
> ---
> Yeah, I know, said so earlier, and posted a simulation showing the
> ripple.
> ---
>
> >Mean current remains much the same.
> >So we're looking for 120v rms, which is what the BR would deliver.
>
> ---
> But, what it won't deliver is the worst-case voltage required over the
> interval required to guarantee the armature will close.

Re ripple: If the relay is designed to run on ac 50 or 60Hz, its
designed and rated to live with the current and force variations that
go along with that, 100-120 times a second. Running it on rectified
mains will only serve to reduce the current variations through the
cycle, it wont cause the relay any issues.

Re rms voltage: With my 2:1 figures, rectified 120v is spot on. With
your 174v figure, 120v is well within the 50% margin. Of course for
some uses that margin would need to be confirmed by testing before
production, and reconfirmed if a new relay type is used. Or as you
say, a cap could be added. Or for off brand consumer goods, in it
goes, relays are good for it.

> >> However, the reactance of the coil will smooth the current and the
> >> addition of a capacitor in parallel with the coil will remove some of
> >> the ripple and allow the coil to see more nearly pure DC.
>
> >and overheat the relay by increasing its rms dc voltage to above 120v.
>
> There's no such thing as "rms dc voltage",

RMS can be applied to any and every waveform, dc included. Its very
relevant when working with rectified ac, semismoothed or unsmoothed.

> and if the relay is
> designed to operate on AC with a certain RMS current in its coil, how
> can it possibly overheat if that current is DC?

With the same current it wont, with higher curren ti will. IIRC you
proposed using 174v rms, that would be ok on your specific relay, but
not a universal solution.

> >> Here's a simulation showing both ways:
>
> >> Version 4
> >> SHEET 1 880 680
> >> WIRE -144 16 -304 16
> >> WIRE 112 16 -144 16
> >> WIRE 448 16 288 16
> >> WIRE 704 16 448 16
> >> WIRE -304 80 -304 16
> >> WIRE 288 80 288 16
> >> WIRE 448 80 448 64
> >> WIRE 480 80 448 80
> >> WIRE 592 80 560 80
> >> WIRE 704 80 704 64
> >> WIRE 704 80 672 80
> >> WIRE -144 112 -144 80
> >> WIRE -112 112 -144 112
> >> WIRE 0 112 -32 112
> >> WIRE 112 112 112 80
> >> WIRE 112 112 80 112
> >> WIRE -144 160 -144 112
> >> WIRE 112 160 112 112
> >> WIRE 448 160 448 80
> >> WIRE 544 160 448 160
> >> WIRE 704 160 704 80
> >> WIRE 704 160 608 160
> >> WIRE -304 224 -304 160
> >> WIRE -144 224 -304 224
> >> WIRE 112 224 -144 224
> >> WIRE 288 224 288 160
> >> WIRE 448 224 288 224
> >> WIRE 704 224 448 224
> >> WIRE -304 272 -304 224
> >> WIRE 288 272 288 224
> >> FLAG -304 272 0
> >> FLAG 288 272 0
> >> SYMBOL ind -128 128 R270
> >> WINDOW 0 32 56 VTop 0
> >> WINDOW 3 5 56 VBottom 0
> >> SYMATTR InstName L1
> >> SYMATTR Value 15
> >> SYMBOL voltage -304 64 R0
> >> WINDOW 3 24 104 Invisible 0
> >> WINDOW 123 0 0 Left 0
> >> WINDOW 39 0 0 Left 0
> >> SYMATTR InstName V1
> >> SYMATTR Value SINE(0 170 60)
> >> SYMBOL diode -160 16 R0
> >> WINDOW 0 4 -52 Left 0
> >> WINDOW 3 -28 -24 Left 0
> >> SYMATTR InstName D1
> >> SYMATTR Value MUR460
> >> SYMBOL diode 128 80 R180
> >> WINDOW 0 1 119 Left 0
> >> WINDOW 3 -33 84 Left 0
> >> SYMATTR InstName D2
> >> SYMATTR Value MUR460
> >> SYMBOL diode 96 160 R0
> >> WINDOW 0 3 89 Left 0
> >> WINDOW 3 -27 118 Left 0
> >> SYMATTR InstName D3
> >> SYMATTR Value MUR460
> >> SYMBOL diode -128 224 R180
> >> WINDOW 0 2 -28 Left 0
> >> WINDOW 3 -31 -57 Left 0
> >> SYMATTR InstName D4
> >> SYMATTR Value MUR460
> >> SYMBOL res -16 128 R270
> >> WINDOW 0 32 56 VTop 0
> >> WINDOW 3 0 56 VBottom 0
> >> SYMATTR InstName R1
> >> SYMATTR Value 4800
> >> SYMBOL ind 464 96 R270
> >> WINDOW 0 32 56 VTop 0
> >> WINDOW 3 5 56 VBottom 0
> >> SYMATTR InstName L2
> >> SYMATTR Value 15
> >> SYMBOL voltage 288 64 R0
> >> WINDOW 3 24 104 Invisible 0
> >> WINDOW 123 0 0 Left 0
> >> WINDOW 39 0 0 Left 0
> >> SYMATTR InstName V2
> >> SYMATTR Value SINE(0 170 60)
> >> SYMBOL diode 432 16 R0
> >> WINDOW 0 4 -52 Left 0
> >> WINDOW 3 -28 -24 Left 0
> >> SYMATTR InstName D5
> >> SYMATTR Value MUR460
> >> SYMBOL diode 720 80 R180
> >> WINDOW 0 1 119 Left 0
> >> WINDOW 3 -33 84 Left 0
> >> SYMATTR InstName D6
> >> SYMATTR Value MUR460
> >> SYMBOL diode 688 160 R0
> >> WINDOW 0 3 89 Left 0
> >> WINDOW 3 -27 118 Left 0
> >> SYMATTR InstName D7
> >> SYMATTR Value MUR460
> >> SYMBOL diode 464 224 R180
> >> WINDOW 0 2 -28 Left 0
> >> WINDOW 3 -31 -57 Left 0
> >> SYMATTR InstName D8
> >> SYMATTR Value MUR460
> >> SYMBOL res 576 96 R270
> >> WINDOW 0 32 56 VTop 0
> >> WINDOW 3 0 56 VBottom 0
> >> SYMATTR InstName R2
> >> SYMATTR Value 4800
> >> SYMBOL cap 608 144 R90
> >> WINDOW 0 0 32 VBottom 0
> >> WINDOW 3 32 32 VTop 0
> >> SYMATTR InstName C1
> >> SYMATTR Value 10µ
> >> TEXT -298 246 Left 0 !.tran .05
>
> >> If the relay is spec'ed as "must make" at 80% of rated current through
> >> the coil (~29mA), then note that with a 10µF cap in parallel with the
> >> coil the relay will _always_ make using full-wave rectified 120V 60Hz
> >> mains.
>
> --
> JF

== 3 of 7 ==
Date: Wed, Aug 31 2011 11:06 am
From: The Ghost In The Machine

On Aug 31, 12:38 pm, NT <meow2...@care2.com> wrote:
> On Aug 31, 1:36 am, John Fields <jfie...@austininstruments.com> wrote:
>
>
>
>
>
> > On Tue, 30 Aug 2011 05:11:20 -0700 (PDT), NT <meow2...@care2.com>
> > wrote:
> > >On Aug 30, 12:39 pm, John Fields <jfie...@austininstruments.com>
> > >wrote:
> > >> On Mon, 29 Aug 2011 07:25:23 -0700 (PDT), NT <meow2...@care2.com>
> > >> wrote:
>
> > >> >IME relays pull in at in the region of half rated voltage, and dc
> > >> >ratings are typically about half the voltage of the ac rating, which
> > >> >gives an idea of how much current is determined by L and how much by
> > >> >R.
>
> > >> ---
> > >> IME, most relays (with either AC or DC coils) are guaranteed to pull
> > >> in at about 80% of their rated coil voltage, so I'm at a loss trying
> > >> to understand what you meant by: "dc ratings are typically about half
> > >> of the ac rating."
>
> > >> Can you elaborate, please?
>
> > >When relays have dual ratings for ac and dc, its normal for the dc
> > >voltage rating to be half the ac voltage rating.
>
> > >> >Running your relay on 220v 60Hz it will work fine.
>
> > >> Knowing nothing about the contactor, other than that it's specified to
> > >> energize when 240V 50Hz is placed across the coil, your imprimatur is
> > >> premature.
>
> > >I really dont agree. I do know the basics about relays, and one
> > >normally finds that pull-in occurs at around 50% rated voltage. The OP
> > >is welcome to test theirs to see if it behaves the usual way.
>
> > >> >Contact closing speed will be slightly slower. Margin will be reduced,
> > >> >but its only being reduced from enormous to slightly less enormous,
> > >> >so its a non-issue except in very unusual situations.
>
> > >> It seems you've forgotten that when the armature makes, and the
> > >> magnetic circuit is closed, the inductance of the coil will rise.
>
> > >I dont know why you think I've forgotten it. What's relevant here is
> > >inductance in the closed position.
>
> > I disagree.
>
> > Since the relay is open when power is applied to the coil, it's the
> > open inductance (and the resistance, of course) which will determine
> > how much current will flow through the coil, that current being what
> > generates the magnetic field to start the armature on its way.
>
> yup
>
> > Then when the relay closes, the closed inductance comes into play and
> > holds the armature in place until the current through the coil is
> > reduced to a point where the armature's return spring overcomes the
> > weakened magnetic field, allowing the armature to open.
>
> yes. I guess in theory both matter, one determines closing behaviour,
> the other ensures the relay doesnt overheat. In practice though the
> margins are very large, and its normal to simply fix holding current
> to suit the relay, and not worry about closing current, which will be
> so close as to make no real world difference in all but exceptional
> circumstances. But yes, we can consider both if need be.
>
>
>
>
>
> > >> Such being the case, the current in it will diminish,
>
> > >true with all relays under all ac conditions. Theyre designed to work
> > >that way.
>
> > >> reducing the
> > >> hold on the armature and making the contacts more likely to chatter.
>
> > >No, its exactly how theyre designed to operate.
>
> > >> >The vibration tolerance of
> > >> >the contacts will be little affected in practice; if your environment
> > >> >is harsh enough to shake the relay contact open, then you've got
> > >> >bigger worries than contacts crackling.
> > >> >If instead you meant you would use it on 110v 60Hz, then dont. But you
> > >> >could use diodes to get a higher dc voltage and use that.
>
> > >> Interesting conjecture.
>
> > >Where's the conjecture? I get the feeling you could do with bringing
> > >your skills up to speed on relays.
>
> > ---
> > Perhaps.
> > ---
>
> > >> Something like this?
>
> > >> +-----+
> > >> 120AC>--|~ +|----+
> > >> | | |
> > >> | | [COIL]
> > >> | | |
> > >> 120AC>--|~ -|----+
> > >> +-----+
>
> > >That would work.
>
> > Not in all cases, certainly.
>
> I'd like to see you find one single electromechanical relay that wont
> work for.
>
>
>
>
>
> > >> Since the coil has an impedance of about 6600 ohms at 50Hz, then the
> > >> current through it will be:
>
> > >> E 240V
> > >> I = --- = ------- = 0.036A = 36mA
> > >> Z 6600R
>
> > >> Then, since the coil has a resistance of 4800 ohms, the DC voltage
> > >> across it required to force 36mA through it would be:
>
> > >> E = IR = 0.036A * 4800R ~ 174V.
>
> > >You're not saying where you got those figures from.
>
> > ---
> > The P&B MR5A I talked about in an earlier post, which has a 240V
> > 50/60Hz coil, a coil resistance of 4800 ohms, an impedance of ~ 6600
> > ohms at 50 Hz, an open inductance of 14.5 henrys, and a closed
> > inductance of 16 henrys
> > >Typically dc rating is half ac rating.
>
> > But I don't think "typical" is what we're after since we want
> > something that will _always_ work.
>
> This 2:1 ratio normally is good for relays, and the OP can check his
> to see if it conforms to that. If it does, the thing will always work
> when subject to this formula.
>
> FWIW, when ac is applied you get puling force plus vibration. With dc
> there is no vibration component when its closed, so less holding
> current is needed. How much less I've really no idea.
>
> Some relays are fast movers capable of 100s of Hz, some are slow. Ac
> relays can always work on dc, but dc ones often dont work ok on ac.
>
>
>
>
>
> > Since current is what's doing the work, my real-world example shows
> > that 240V 50 Hz RMS impressed across a load with an impedance of 6600
> > ohms will force 36mA RMS of current through the load.
>
> > Then, since it's current that's doing the work, 36mA of DC through the
> > coil should accomplish the same thing.
> > ---
>
> > >> The peak voltage out of the bridge would be:
>
> > >> E = RMS * sqrt(2) = 120 * 1.414 ~ 170V.
>
> > >> Pretty close, but at 120Hz, the reactance of the coil would increase,
> > >> limiting the current to something less than the 36mA needed to close
> > >> the armature.
>
> > >The effect of the relay's inductance, when run off a BR, is simply to
> > >smooth the current flow somewhat.
>
> > ---
> > Yeah, I know, said so earlier, and posted a simulation showing the
> > ripple.
> > ---
>
> > >Mean current remains much the same.
> > >So we're looking for 120v rms, which is what the BR would deliver.
>
> > ---
> > But, what it won't deliver is the worst-case voltage required over the
> > interval required to guarantee the armature will close.
>
> Re ripple: If the relay is designed to run on ac 50 or 60Hz, its
> designed and rated to live with the current and force variations that
> go along with that, 100-120 times a second. Running it on rectified
> mains will only serve to reduce the current variations through the
> cycle, it wont cause the relay any issues.
>
> Re rms voltage: With my 2:1 figures, rectified 120v is spot on. With
> your 174v figure, 120v is well within the 50% margin. Of course for
> some uses that margin would need to be confirmed by testing before
> production, and reconfirmed if a new relay type is used. Or as you
> say, a cap could be added. Or for off brand consumer goods, in it
> goes, relays are good for it.
>
> > >> However, the reactance of the coil will smooth the current and the
> > >> addition of a capacitor in parallel with the coil will remove some of
> > >> the ripple and allow the coil to see more nearly pure DC.
>
> > >and overheat the relay by increasing its rms dc voltage to above 120v.
>
> > There's no such thing as "rms dc voltage",
>
> RMS can be applied to any and every waveform, dc included. Its very
> relevant when working with rectified ac, semismoothed or unsmoothed.
>
> > and if the relay is
> > designed to operate on AC with a certain RMS current in its coil, how
> > can it possibly overheat if that current is DC?
>
> With the same current it wont, with higher curren ti will. IIRC you
> proposed using 174v rms, that would be ok on your specific relay, but
> not a universal solution.
>
> NT
>
>
>
> > >> Here's a simulation showing both ways:
>
> > >> Version 4
> > >> SHEET1 880 680
> > >> WIRE -144 16 -304 16
> > >> WIRE112 16 -144 16
> > >> WIRE448 16 288 16
> > >> WIRE704 16 448 16
> > >> WIRE -304 80 -304 16
> > >> WIRE288 80 288 16
> > >> WIRE448 80 448 64
> > >> WIRE480 80 448 80
> > >> WIRE592 80 560 80
> > >> WIRE704 80 704 64
> > >> WIRE704 80 672 80
> > >> WIRE -144 112 -144 80
> > >> WIRE -112 112 -144 112
> > >> WIRE0 112 -32 112
> > >> WIRE112 112 112 80
> > >> WIRE112 112 80 112
> > >> WIRE -144 160 -144 112
> > >> WIRE112 160 112 112
> > >> WIRE448 160 448 80
> > >> WIRE544 160 448 160
> > >> WIRE704 160 704 80
> > >> WIRE704 160 608 160
> > >> WIRE -304 224 -304 160
> > >> WIRE -144 224 -304 224
> > >> WIRE112 224 -144 224
> > >> WIRE288 224 288 160
> > >> WIRE448 224 288 224
> > >> WIRE704 224 448 224
> > >> WIRE -304 272 -304 224
> > >> WIRE288 272 288 224
> > >> FLAG -304 272 0
> > >> FLAG288 272 0
> > >> SYMBOL ind -128 128 R270
> > >> WINDOW 0 32 56 VTop 0
> > >> WINDOW 3 5 56 VBottom 0
> > >> SYMATTR InstName L1
> > >> SYMATTR Value 15
> > >> SYMBOL voltage -304 64 R0
> > >> WINDOW 3 24 104 Invisible 0
> > >> WINDOW 123 0 0 Left 0
> > >> WINDOW 39 0 0 Left 0
> > >> SYMATTR InstName V1
> > >> SYMATTR Value SINE(0 170 60)
> > >> SYMBOL diode -160 16 R0
> > >> WINDOW 0 4 -52 Left 0
> > >> WINDOW 3 -28 -24 Left 0
> > >> SYMATTR InstName D1
> > >> SYMATTR Value MUR460
> > >> SYMBOL diode 128 80 R180
> > >> WINDOW 0 1 119 Left 0
> > >> WINDOW 3 -33 84 Left 0
> > >> SYMATTR InstName D2
> > >> SYMATTR Value MUR460
> > >> SYMBOL diode 96 160 R0
> > >> WINDOW 0 3 89 Left 0
> > >> WINDOW 3 -27 118 Left 0
> > >> SYMATTR InstName D3
> > >> SYMATTR Value MUR460
> > >> SYMBOL diode -128 224 R180
> > >> WINDOW 0 2 -28 Left 0
> > >> WINDOW 3 -31 -57 Left 0
> > >> SYMATTR InstName D4
> > >> SYMATTR Value MUR460
> > >> SYMBOL res -16 128 R270
> > >> WINDOW 0 32 56 VTop 0
> > >> WINDOW 3 0 56 VBottom 0
> > >> SYMATTR InstName R1
> > >> SYMATTR Value 4800
> > >> SYMBOL ind 464 96 R270
> > >> WINDOW 0 32 56 VTop 0
> > >> WINDOW 3 5 56 VBottom 0
> > >> SYMATTR InstName L2
> > >> SYMATTR Value 15
> > >> SYMBOL voltage 288 64 R0
> > >> WINDOW 3 24 104 Invisible 0...
>
> read more »

YES A-NT-MAN BUT THE RMS REFERS TO THE AC WAVEFORM NOT THE DC OUTPUT.
HENCE THERE IS NO SUCH THING AS RMS DC VOLTAGE.
PATECUM
TGITM

== 4 of 7 ==
Date: Wed, Aug 31 2011 11:11 am
From: John S

On 8/31/2011 1:06 PM, The Ghost In The Machine wrote:
>
> YES A-NT-MAN BUT THE RMS REFERS TO THE AC WAVEFORM NOT THE DC OUTPUT.
> HENCE THERE IS NO SUCH THING AS RMS DC VOLTAGE.
> PATECUM
> TGITM

Actually, RMS DC voltage is a redundant expression since DC is RMS.

== 5 of 7 ==
Date: Wed, Aug 31 2011 12:33 pm
From: NT

On Aug 31, 7:11 pm, John S <soph...@invalid.org> wrote:
> On 8/31/2011 1:06 PM, The Ghost In The Machine wrote:
>
>
>
> > YES A-NT-MAN BUT THE RMS REFERS TO THE AC WAVEFORM NOT THE DC OUTPUT.
> > HENCE THERE IS NO SUCH THING AS RMS DC VOLTAGE.
> > PATECUM
> > TGITM

Root Mean Square does not imply an ac waveform, its jsut most commonly
used for ac waveforms. Every stable waveform has an rms value, even
perfect dc.

> Actually, RMS DC voltage is a redundant expression since DC is RMS.

I realised it was perhaps not the best phrasing. But... would the dc
component be the average V or the rms?

== 6 of 7 ==
Date: Wed, Aug 31 2011 1:02 pm
From: Jeffrey Angus

On 8/31/2011 2:33 PM, NT wrote:
> I realised it was perhaps not the best phrasing. But... would the dc
> component be the average V or the rms?

DC would be the RMS value. Because, RMS means "This is what the DC
value would be."

Jeff

--
"Everything from Crackers to Coffins"

== 7 of 7 ==
Date: Wed, Aug 31 2011 1:41 pm
From: "Ian Field"

"Jeffrey Angus" <grendelair@aim.com> wrote in message
news:j3m408$fqf$1@dont-email.me...
> On 8/31/2011 2:33 PM, NT wrote:
>> I realised it was perhaps not the best phrasing. But... would the dc
>> component be the average V or the rms?
>
> DC would be the RMS value. Because, RMS means "This is what the DC
> value would be."

Years ago when I needed more power from a soldering iron I used to feed the
240VRMS through a rectifier/reservoir to get aproximately 320VDC.

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sci.electronics.repair - 25 new messages in 6 topics - digest

10:21 PM Penedão 0 comments

sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

sci.electronics.repair@googlegroups.com

Today's topics:

* Tektronix 7603 - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/efb86f5dc14fc24b?hl=en
* Why do some manufacturers wrap the electrolytic capacitor that gets the
hottest in a switching power supply in shrink wrap? - 6 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/2a675f3c64fd62cc?hl=en
* Contactor coil: 50 Hz vs. 60 Hz - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/0d1a06068779ce43?hl=en
* Yellow Glue strikes again - 13 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/9d8bded3db582b06?hl=en
* Tek 465 - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/b9f473fde6856891?hl=en
* Motor start/stop switch with integrated mini contactor? - 2 messages, 2
authors
http://groups.google.com/group/sci.electronics.repair/t/13b233689d902984?hl=en

== 1 of 2 ==
Date: Tues, Aug 30 2011 3:12 pm
From: "Michael A. Terrell"

Jeff Urban wrote:
>
> I do not care to join any more groups. This is sci.electronics.repair
> correct ? This is an electronic instrument I wish to repair.
>
> I need another internet ID like a hole in the head, and let me tell
> you when I was in my twenties I got shot in the face, so I can assure
> you I don't need any more holes in my head. What is Usenet dead ? I
> know I am posting through Google but that's the only way I have right
> now. I was here a long time ago and if I could I would retrieve my old
> ID, but I can't.
>
> S.E.R. is dead ? I have to go to yahoo ?
>
> Sorry, I'll just sell the Tek. Fuck it.

This is the reason so many have left the group for greener pastures.
They got tired of whiny jerks like you.

All you need is a Yahoo Email address to join any Yahoo group that
will take you, but they aren't interested in pissing and moaning.

You aren't related to Bill Turner, by any chance? You bitch and
whine just like he used to.

--
You can't have a sense of humor, if you have no sense.

== 2 of 2 ==
Date: Tues, Aug 30 2011 10:18 pm
From: Jeff Urban

"This is the reason so many have left the group for greener pastures.
They got tired of whiny jerks like you. "

You know a hell of alot about me out of one post. I am a whiney
jerk ?

Was that your goal ? Hope so, so you can be proud of yourself. And,
this little self help group here, help your self. Yuo DON'T want me to
lift a finger, now.

Tell Jim Yanik I am sorry, I'll see him at the NRA meeting. The rest
of you, go fuck yourselves.

Fukt if I have to sign this, you knopw who the fuck I am.

== 1 of 6 ==
Date: Tues, Aug 30 2011 3:31 pm
From: dplatt@radagast.org (Dave Platt)

In article <3giq5793mdtgi0f6ssmf2pp79bn9ukbeuv@4ax.com>,
Chuck <chuckh@deja.net> wrote:

>Extron has been doing this for years and of course it is the first
>part to fail in their units. Smart Technologies Sympodium power
>supplies, that they have contract built in China, fail in a year or so
>for the same reason. Technicians and electronic engineers at my work
>place can't think of a rational reason why these manufacturers do
>this. This is pro gear where reliability is a great concern so it
>doesn't seem to be planned failure mode. Thanks. Chuck

I've heard it said:

"When the question is `Why is company X doing seemingly irrational
thing Y in their product design?', the answer is most commonly
`Money',"

Electrolytic capacitors are normally shipped, by their manufacturers,
in a plastic insulating jacket. It's the common method used to
insulate the cases against accidental shorts, and to allow convenient
marking (no separate marking process is required during manufacture,
since the markings are manufactured into the plastic).

Almost all "commodity" 'lytics are of this sort. If you want caps
with another sort of jacketing (even "none at all") you'd probably
have to special-order them, there would be far fewer possible sources,
and the cost per piece would end up being significantly higher.

There's immense price-pressure and competition in the electronics
manufacturing business, even for "pro gear". A matter of a few cents
per power supply can make the difference between a contract
manufacturer getting, or losing the bid. The manufacturers thus have
a *very* strong incentive to use standard parts... and, in fact, the
cheapest and lowest-rated ones which will allow the final supply to
pass its paper requirements (which may not include long-life survival
tests).

I've heard that it's quite common for overseas contract manufacturers
to covertly "down-rate" parts, after they win a bid... that is, the
specific caps and resistors and etc. that they stuff into the
production lots, may not be the same as the ones they stuffed into the
samples that they submitted. Unless you stand over 'em with a club,
and do a strict verification of what you receive, you may get
lower-quality subsystems than you had been originally offered. You
might even get counterfeit parts (e.g. cheap 85-degree-C caps, which
have been falsely labeled as 105-degree-C, or generic caps falsely
marked to indicate low-ESR, high-ripple-current ruggedness).

If the final system survives to the end of its warranty period, many
companies seem to feel that this is Plenty Good Enough, and brings in
additional revenue for repairs and replacements.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

== 2 of 6 ==
Date: Tues, Aug 30 2011 3:41 pm
From: stratus46@yahoo.com

On Aug 30, 2:48 pm, Jim Yanik <jya...@abuse.gov> wrote:
> Chuck <chu...@deja.net> wrote innews:
3giq5793mdtgi0f6ssmf2pp79bn9ukbeuv@4ax.com:
>
> > Extron has been doing this for years and of course it is the
first
> > part to fail in their units. Smart Technologies Sympodium power
> > supplies, that they have contract built in China, fail in a year
or so
> > for the same reason. Technicians and electronic engineers at my
work
> > place can't think of a rational reason why these manufacturers do
> > this. This is pro gear where reliability is a great concern so
it
> > doesn't seem to be planned failure mode. Thanks. Chuck
>
> IMO,in a proper design,the caps should not be getting hot.
> Caps should be sized and rated properly,with a fair amount of
excess
> capacity,not sized/rated right at the margins.
> We have inexpensive thermal imaging available that can identify hot
spots
> so that they can be corrected before the design is finalized.
>
> --
> Jim Yanik
> jyanik
> at
> localnet
> dot com

The caps may not be getting hot on their own but get damaged from
nearby hot items. We had 16 Samsung digital tuners at work that had 1
cap that fails next to a diode on a heatsink. We replaced it with a
very good grade cap but extended the leads just enough to lay the cap
on its side away from the heatsink. Luckily room to do that existed.

G²

== 3 of 6 ==
Date: Tues, Aug 30 2011 5:41 pm
From: "Phil Allison"

"Chuck"
>
> Extron has been doing this for years and of course it is the first
> part to fail in their units. Smart Technologies Sympodium power
> supplies, that they have contract built in China, fail in a year or so
> for the same reason.

** What a load of bullshit !!

Putting a shrink wrap sleeve around an electro will not make it fail early.

I bet the sleeve is there for a totally non electronic reason - like being
able to put markings on it with a pen.

.... Phil

== 4 of 6 ==
Date: Tues, Aug 30 2011 6:01 pm
From: Jeff Liebermann

On Tue, 30 Aug 2011 15:47:21 -0500, Chuck <chuckh@deja.net> wrote:

Probably to keep you from touching the can, which is probably
electrically hot. The life you save may be your own.

Electrolytic caps do not normally get hot. There is a temperature
rise equal to the ripple current times the square of the ESR
(equivlent series resistance). If the ESR is too high, usually due to
underspecifying the voltage rating or capacitor type, it will get
warm. There are derating curves for capacitors at various
temperatures. There are also lifetime prediction calculators which
include the operating temperature.

If you're shopping for a conspiracy theory, I guess the capacitors are
badly specified or picking up heat from adjacent heat dissipating
devices. A nearby resistor or heat sunk xsistor will heat up a cap
quite nicely. The shrink tube will have little effect on the cap
temperature. Black absorbs more heat, so it might be slightly warmer
from nearby radiation. At best, maybe a degree or two.

Pro audio is the same as consumer audio, except for the price tag and
the hype.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 5 of 6 ==
Date: Tues, Aug 30 2011 6:14 pm
From: "Phil Allison"

"Jeff Liebermann"
>
> Electrolytic caps do not normally get hot. There is a temperature
> rise equal to the ripple current times the square of the ESR
> (equivlent series resistance).

** Wanna try that again ??

> Pro audio is the same as consumer audio, except for the price tag and
> the hype.

** Only true of most Chinese made stuff.

.... Phil

== 6 of 6 ==
Date: Tues, Aug 30 2011 6:26 pm
From: Jeff Liebermann

On Wed, 31 Aug 2011 11:14:07 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>"Jeff Liebermann"
>>
>> Electrolytic caps do not normally get hot. There is a temperature
>> rise equal to the ripple current times the square of the ESR
>> (equivlent series resistance).
>
>
>** Wanna try that again ??

Oops.
Powah = Ripple Current squared times ESR.
Thanks (grumble)...

>> Pro audio is the same as consumer audio, except for the price tag and
>> the hype.
>
>** Only true of most Chinese made stuff.

I didn't know that anything was made outside of China these days. If
the boards and boxes aren't built in China, the components probably
are made in China.
<http://www.made-in-china.com/products-search/hot-china-products/Pro_Audio.html>
<http://www.made-in-china.com/Consumer-Electronics-Catalog/Professional-Audio-Lighting.html>
<http://www.diytrade.com/china/4/products-list/0-k-c-1/pro_audio.html>
<http://www.alibaba.com/countrysearch/CN/pro_audio.html>

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 1 of 1 ==
Date: Tues, Aug 30 2011 5:36 pm
From: John Fields

On Tue, 30 Aug 2011 05:11:20 -0700 (PDT), NT <meow2222@care2.com>
wrote:

>On Aug 30, 12:39 pm, John Fields <jfie...@austininstruments.com>
>wrote:
>> On Mon, 29 Aug 2011 07:25:23 -0700 (PDT), NT <meow2...@care2.com>
>> wrote:
>>
>> >IME relays pull in at in the region of half rated voltage, and dc
>> >ratings are typically about half the voltage of the ac rating, which
>> >gives an idea of how much current is determined by L and how much by
>> >R.
>>
>> ---
>> IME, most relays (with either AC or DC coils) are guaranteed to pull
>> in at about 80% of their rated coil voltage, so I'm at a loss trying
>> to understand what you meant by: "dc ratings are typically about half
>> of the ac rating."
>>
>> Can you elaborate, please?
>
>When relays have dual ratings for ac and dc, its normal for the dc
>voltage rating to be half the ac voltage rating.
>
>
>> >Running your relay on 220v 60Hz it will work fine.
>>
>> Knowing nothing about the contactor, other than that it's specified to
>> energize when 240V 50Hz is placed across the coil, your imprimatur is
>> premature.
>
>I really dont agree. I do know the basics about relays, and one
>normally finds that pull-in occurs at around 50% rated voltage. The OP
>is welcome to test theirs to see if it behaves the usual way.
>
>
>> >Contact closing speed will be slightly slower. Margin will be reduced,
>> >but its only being reduced from enormous to slightly less enormous,
>> >so its a non-issue except in very unusual situations.
>>
>> It seems you've forgotten that when the armature makes, and the
>> magnetic circuit is closed, the inductance of the coil will rise.
>
>I dont know why you think I've forgotten it. What's relevant here is
>inductance in the closed position.

---
I disagree.

Since the relay is open when power is applied to the coil, it's the
open inductance (and the resistance, of course) which will determine
how much current will flow through the coil, that current being what
generates the magnetic field to start the armature on its way.

Then when the relay closes, the closed inductance comes into play and
holds the armature in place until the current through the coil is
reduced to a point where the armature's return spring overcomes the
weakened magnetic field, allowing the armature to open.
---

>> Such being the case, the current in it will diminish,
>
>true with all relays under all ac conditions. Theyre designed to work
>that way.
>
>> reducing the
>> hold on the armature and making the contacts more likely to chatter.
>
>No, its exactly how theyre designed to operate.
>
>
>> >The vibration tolerance of
>> >the contacts will be little affected in practice; if your environment
>> >is harsh enough to shake the relay contact open, then you've got
>> >bigger worries than contacts crackling.
>> >If instead you meant you would use it on 110v 60Hz, then dont. But you
>> >could use diodes to get a higher dc voltage and use that.
>>
>> Interesting conjecture.
>
>Where's the conjecture? I get the feeling you could do with bringing
>your skills up to speed on relays.

---
Perhaps.
---

>> Something like this?
>>
>> +-----+
>> 120AC>--|~ +|----+
>> | | |
>> | | [COIL]
>> | | |
>> 120AC>--|~ -|----+
>> +-----+
>
>That would work.

---
Not in all cases, certainly.
---
>
>
>> Since the coil has an impedance of about 6600 ohms at 50Hz, then the
>> current through it will be:
>>
>> E 240V
>> I = --- = ------- = 0.036A = 36mA
>> Z 6600R
>>
>> Then, since the coil has a resistance of 4800 ohms, the DC voltage
>> across it required to force 36mA through it would be:
>>
>> E = IR = 0.036A * 4800R ~ 174V.
>
>You're not saying where you got those figures from.

---
The P&B MR5A I talked about in an earlier post, which has a 240V
50/60Hz coil, a coil resistance of 4800 ohms, an impedance of ~ 6600
ohms at 50 Hz, an open inductance of 14.5 henrys, and a closed
inductance of 16 henrys
---

>Typically dc rating is half ac rating.

---
But I don't think "typical" is what we're after since we want
something that will _always_ work.

Since current is what's doing the work, my real-world example shows
that 240V 50 Hz RMS impressed across a load with an impedance of 6600
ohms will force 36mA RMS of current through the load.

Then, since it's current that's doing the work, 36mA of DC through the
coil should accomplish the same thing.
---

>> The peak voltage out of the bridge would be:
>>
>> E = RMS * sqrt(2) = 120 * 1.414 ~ 170V.
>>
>> Pretty close, but at 120Hz, the reactance of the coil would increase,
>> limiting the current to something less than the 36mA needed to close
>> the armature.
>
>The effect of the relay's inductance, when run off a BR, is simply to
>smooth the current flow somewhat.

---
Yeah, I know, said so earlier, and posted a simulation showing the
ripple.
---

>Mean current remains much the same.
>So we're looking for 120v rms, which is what the BR would deliver.

---
But, what it won't deliver is the worst-case voltage required over the
interval required to guarantee the armature will close.
---

>> However, the reactance of the coil will smooth the current and the
>> addition of a capacitor in parallel with the coil will remove some of
>> the ripple and allow the coil to see more nearly pure DC.
>
>and overheat the relay by increasing its rms dc voltage to above 120v.

---
There's no such thing as "rms dc voltage", and if the relay is
designed to operate on AC with a certain RMS current in its coil, how
can it possibly overheat if that current is DC?
---

>> Here's a simulation showing both ways:
>>
>> Version 4
>> SHEET 1 880 680
>> WIRE -144 16 -304 16
>> WIRE 112 16 -144 16
>> WIRE 448 16 288 16
>> WIRE 704 16 448 16
>> WIRE -304 80 -304 16
>> WIRE 288 80 288 16
>> WIRE 448 80 448 64
>> WIRE 480 80 448 80
>> WIRE 592 80 560 80
>> WIRE 704 80 704 64
>> WIRE 704 80 672 80
>> WIRE -144 112 -144 80
>> WIRE -112 112 -144 112
>> WIRE 0 112 -32 112
>> WIRE 112 112 112 80
>> WIRE 112 112 80 112
>> WIRE -144 160 -144 112
>> WIRE 112 160 112 112
>> WIRE 448 160 448 80
>> WIRE 544 160 448 160
>> WIRE 704 160 704 80
>> WIRE 704 160 608 160
>> WIRE -304 224 -304 160
>> WIRE -144 224 -304 224
>> WIRE 112 224 -144 224
>> WIRE 288 224 288 160
>> WIRE 448 224 288 224
>> WIRE 704 224 448 224
>> WIRE -304 272 -304 224
>> WIRE 288 272 288 224
>> FLAG -304 272 0
>> FLAG 288 272 0
>> SYMBOL ind -128 128 R270
>> WINDOW 0 32 56 VTop 0
>> WINDOW 3 5 56 VBottom 0
>> SYMATTR InstName L1
>> SYMATTR Value 15
>> SYMBOL voltage -304 64 R0
>> WINDOW 3 24 104 Invisible 0
>> WINDOW 123 0 0 Left 0
>> WINDOW 39 0 0 Left 0
>> SYMATTR InstName V1
>> SYMATTR Value SINE(0 170 60)
>> SYMBOL diode -160 16 R0
>> WINDOW 0 4 -52 Left 0
>> WINDOW 3 -28 -24 Left 0
>> SYMATTR InstName D1
>> SYMATTR Value MUR460
>> SYMBOL diode 128 80 R180
>> WINDOW 0 1 119 Left 0
>> WINDOW 3 -33 84 Left 0
>> SYMATTR InstName D2
>> SYMATTR Value MUR460
>> SYMBOL diode 96 160 R0
>> WINDOW 0 3 89 Left 0
>> WINDOW 3 -27 118 Left 0
>> SYMATTR InstName D3
>> SYMATTR Value MUR460
>> SYMBOL diode -128 224 R180
>> WINDOW 0 2 -28 Left 0
>> WINDOW 3 -31 -57 Left 0
>> SYMATTR InstName D4
>> SYMATTR Value MUR460
>> SYMBOL res -16 128 R270
>> WINDOW 0 32 56 VTop 0
>> WINDOW 3 0 56 VBottom 0
>> SYMATTR InstName R1
>> SYMATTR Value 4800
>> SYMBOL ind 464 96 R270
>> WINDOW 0 32 56 VTop 0
>> WINDOW 3 5 56 VBottom 0
>> SYMATTR InstName L2
>> SYMATTR Value 15
>> SYMBOL voltage 288 64 R0
>> WINDOW 3 24 104 Invisible 0
>> WINDOW 123 0 0 Left 0
>> WINDOW 39 0 0 Left 0
>> SYMATTR InstName V2
>> SYMATTR Value SINE(0 170 60)
>> SYMBOL diode 432 16 R0
>> WINDOW 0 4 -52 Left 0
>> WINDOW 3 -28 -24 Left 0
>> SYMATTR InstName D5
>> SYMATTR Value MUR460
>> SYMBOL diode 720 80 R180
>> WINDOW 0 1 119 Left 0
>> WINDOW 3 -33 84 Left 0
>> SYMATTR InstName D6
>> SYMATTR Value MUR460
>> SYMBOL diode 688 160 R0
>> WINDOW 0 3 89 Left 0
>> WINDOW 3 -27 118 Left 0
>> SYMATTR InstName D7
>> SYMATTR Value MUR460
>> SYMBOL diode 464 224 R180
>> WINDOW 0 2 -28 Left 0
>> WINDOW 3 -31 -57 Left 0
>> SYMATTR InstName D8
>> SYMATTR Value MUR460
>> SYMBOL res 576 96 R270
>> WINDOW 0 32 56 VTop 0
>> WINDOW 3 0 56 VBottom 0
>> SYMATTR InstName R2
>> SYMATTR Value 4800
>> SYMBOL cap 608 144 R90
>> WINDOW 0 0 32 VBottom 0
>> WINDOW 3 32 32 VTop 0
>> SYMATTR InstName C1
>> SYMATTR Value 10µ
>> TEXT -298 246 Left 0 !.tran .05
>>
>> If the relay is spec'ed as "must make" at 80% of rated current through
>> the coil (~29mA), then note that with a 10µF cap in parallel with the
>> coil the relay will _always_ make using full-wave rectified 120V 60Hz
>> mains.

--
JF

== 1 of 13 ==
Date: Tues, Aug 30 2011 5:59 pm
From: "Phil Allison"

** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
still with us.

Most of you will have seen it holding parts down to PCBs on Asian made
equipment and many of those will have seen what happens if the parts
involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor ( M1
Active, Chinese made) ) which has blown up big time because of the damn
Yellow Glue used to secure a ferrite toroidal coil. All the glue used had
gone brown or back ( ie carbonised ) on this coil and arced across nearby
tracks taking out the main switching MOSFET, its drive IC and associated
transistors, high speed diodes and even the AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The same glue
was attacking parts elsewhere on the board too ( it corrodes copper) and had
to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs NEVER going
to wake up ??

..... Phil

== 2 of 13 ==
Date: Tues, Aug 30 2011 6:28 pm
From: Jeff Liebermann

On Wed, 31 Aug 2011 10:59:58 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
>still with us.
>
>Most of you will have seen it holding parts down to PCBs on Asian made
>equipment and many of those will have seen what happens if the parts
>involved get hot.

Is that hot melt glue or something else?
Hot melt should, umm... melt, not burn.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 3 of 13 ==
Date: Tues, Aug 30 2011 6:34 pm
From: "Phil Allison"

"Jeff Liebermann"

>
> Is that hot melt glue or something else?

** So you do no repair work at all ?

.... Phil

== 4 of 13 ==
Date: Tues, Aug 30 2011 6:36 pm
From: Jeffrey Angus

On 8/30/2011 8:28 PM, Jeff Liebermann wrote:
> Is that hot melt glue or something else?
> Hot melt should, umm... melt, not burn.

No, this crap looks like 3M weather strip adhesive.
Sometimes it looks like it's applied sparingly, other times
it looks like it was put on with a caulking gun.

Jeff

--
"Everything from Crackers to Coffins"

== 5 of 13 ==
Date: Tues, Aug 30 2011 6:50 pm
From: "Phil Allison"

"Jeffrey Angus"
>
> No, this crap looks like 3M weather strip adhesive.
> Sometimes it looks like it's applied sparingly, other times
> it looks like it was put on with a caulking gun.
>

** I've always wanted to know just WFT it really is !!

At first impression, it looks like ordinary contact adhesive - but it is
quick setting and dries to a hard surface. With time and heat it become tan
coloured and brittle. Then it goes toast brown and becomes corrosive and
conductive.

If coating the pins of an op-amp, the leakage current causes DC offsets and
crackling noises.

If coating small diodes and resistors etc - it will slowly eat the leads
right off.

If coating PCB tracks with hundreds of volts between them, the conduction
heats the glue directly until there is an explosion.

IME , a local ambient temp of about 55C is enough to set it off on its
pathway to hell.

.... Phil

== 6 of 13 ==
Date: Tues, Aug 30 2011 6:51 pm
From: Jeff Liebermann

On Wed, 31 Aug 2011 11:34:43 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>"Jeff Liebermann"
>>
>> Is that hot melt glue or something else?
>
>** So you do no repair work at all ?

Just answer the question. I've seen plenty of hot melt glue being
used. It comes in clear, yellow, and brown. I've never noticed
anything else. Maybe it's a pro-audio only thing? I don't do any
pro-audio as what little audio repair work I do usually doesn't
involve incinerated parts and carbonized yellow glue.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 7 of 13 ==
Date: Tues, Aug 30 2011 6:53 pm
From: Jeffrey Angus

On 8/30/2011 8:50 PM, Phil Allison wrote:
> ** I've always wanted to know just WFT it really is !!

It's probably related to that crap rubber they love to use
for drive belts and such that turns to extremely sticky goo
that's next to impossible to clean off of everything it
touches.

Jeff

--
"Everything from Crackers to Coffins"

== 8 of 13 ==
Date: Tues, Aug 30 2011 6:57 pm
From: "Phil Allison"

"Jeff Liebermann"
>>
>>> Is that hot melt glue or something else?
>>
>>** So you do no repair work at all ?
>
> Just answer the question.

** You are not a repair tech, or you would have seen it many times.

Always Asian made gear, from about the 1980s onwards.

TV sets, VCRs, SMPSs anything where the maker felt it was a good idea to
glue things to the PCB.

Do a Google search on this NG under " yellow glue".

..... Phil

== 9 of 13 ==
Date: Tues, Aug 30 2011 6:56 pm
From: Jeff Liebermann

On Wed, 31 Aug 2011 11:50:53 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>** I've always wanted to know just WFT it really is !!

This description seems to fit:
<http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant_flame_retardant.html>
"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"

Note the photos. Is that it? I'll do some more Googling later. Gotta
seperate my customers from their money.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 10 of 13 ==
Date: Tues, Aug 30 2011 6:59 pm
From: Jeff Liebermann

On Tue, 30 Aug 2011 18:56:39 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Wed, 31 Aug 2011 11:50:53 +1000, "Phil Allison" <phil_a@tpg.com.au>
>wrote:
>
>>** I've always wanted to know just WFT it really is !!
>
>This description seems to fit:
><http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant_flame_retardant.html>
>"One component solvent resistant flame-retardant waterproof yellow
>fixing adhesive glue for electronic components"
>
>Note the photos. Is that it? I'll do some more Googling later. Gotta
>seperate my customers from their money.

More:
<http://www.aliexpress.com/store/906248/210638773-439369255/accept-sample-order-wholesale-flame-retardant-yellow-adhesive-free-shipping-for-you.html>
The page says it's an "acrylic".

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

== 11 of 13 ==
Date: Tues, Aug 30 2011 7:04 pm
From: Jeffrey Angus

On 8/30/2011 8:56 PM, Jeff Liebermann wrote:
> "One component solvent resistant flame-retardant waterproof yellow
> fixing adhesive glue for electronic components"

Odd, I read this: "Usage: Construction, Fiber & Garment, Footwear "

Jeff, but yeah, that sure looks like it.
Some of the stuff looks almost porous.

Jeff

--
"Everything from Crackers to Coffins"

== 12 of 13 ==
Date: Tues, Aug 30 2011 7:15 pm
From: "Phil Allison"

"Jeff Liebermann"
>
>>** I've always wanted to know just WFT it really is !!
>
> This description seems to fit:
>
> <http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant_flame_retardant.html>
>
> "One component solvent resistant flame-retardant waterproof yellow
> fixing adhesive glue for electronic components"
>
> Note the photos. Is that it?

** Sure as heck looks like the vile stuff.

But the stuff has been in use for decades, firstly with Taiwanese made gear.

The specs quoted do not mention aging or the effects of temperature - so the
marketing is dishonest.

BTW:

the pics show the glue in its liquid state, when dry the surface is quite
dull.

To me, the pics are cringe worthy.

Like looking at pics of child abuse.

.... Phil

== 13 of 13 ==
Date: Tues, Aug 30 2011 7:16 pm
From: Jeff Liebermann

On Tue, 30 Aug 2011 21:04:46 -0500, Jeffrey Angus <grendelair@aim.com>
wrote:

>On 8/30/2011 8:56 PM, Jeff Liebermann wrote:
>> "One component solvent resistant flame-retardant waterproof yellow
>> fixing adhesive glue for electronic components"
>
>Odd, I read this: "Usage: Construction, Fiber & Garment, Footwear "

Sure. Haven't you seen PCB shoes and underwear?
<http://blogs.discovermagazine.com/discoblog/2010/04/07/circuit-board-chic-motherboards-recycled-into-shoes-and-boxers/>
<http://boingboing.net/2010/04/06/circuit-board-shoes.html>
<http://www.zazzle.com/circuit_board_shoes-167287736986690214>
<http://www.xactstudios.com/pcbcreations/>
<http://www.zazzle.com/computer_circuit_board_shoes-167535214684590497>
<https://plus.google.com/103033413691031223989/posts/Kq6qgFDULaj>

>Jeff, but yeah, that sure looks like it.
>Some of the stuff looks almost porous.

Agressive hardener action causing gas bubbles. It's acrylic, but I'm
not familiar with the chemistry. I'll dig it out, later...

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

==============================================================================
TOPIC: Tek 465
http://groups.google.com/group/sci.electronics.repair/t/b9f473fde6856891?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 30 2011 6:04 pm
From: "Mark Zacharias"

"Jim Yanik" <jyanik@abuse.gov> wrote in message
news:Xns9F5170331F672jyaniklocalnetcom@216.168.3.44...
> "Mark Zacharias" <mark_zacharias@labolgcbs.net> wrote in
> news:4e5cb7ec$0$2871$a8266bb1@newsreader.readnews.com:
>
>>> http://www.sphere.bc.ca/test/tek1.html
>>>
>>> --
>>> Cheers,
>>> WB
>>> .............
>>>
>>>
>>> "Mark Zacharias" <mark_zacharias@labolgcbs.net> wrote in message
>>> news:4e58de02$0$2960$a8266bb1@newsreader.readnews.com...
>>>> Just bought a Tek 2246 on the 'Bay. This means the 465 will probably
>>>> need to be sold, assuming the new one is OK and all.
>>>>
>>>> I would entertain serious offers from the good folks who know me
>>>> here on the Group (USA only, please) prior to putting it up on eBay.
>>>>
>>>> Probably about 175.00 plus freight.
>>>>
>>>> Yes, this is the same 'scope Mr. Yanik helped me with recently.
>>>> Replaced a bad bridge rectifier.
>>>>
>>>> Everything works great, bright sharp trace, no burns. Physical
>>>> condition very good, nothing bent or broken, minor scuffs around the
>>>> case but not involving the face. I have several versions of the
>>>> manuals etc on PDF.
>>>>
>>>> Any questions please ask.
>>>>
>>>> Thanks.
>>>>
>>>>
>>>> Mark Z.
>>>>
>>>> --
>>>> "I can't die until the government finds a safe place to bury my
>>>> liver."
>>>
>>
>> "Wild_Bill" <wb_wildbill@XSPAMyahoo.com> wrote in message
>> news:Xf_6q.144751$BZ.132582@en-nntp-03.dc1.easynews.com...
>>> Dunno if the need will arise, but Sphere in Canada has a lot of
>>> online info wrt Tek equipment (and numerous other brands) parts,
>>> parts cross-reference lists, etc.
>>>
>>
>> Yeah - this is where I got that sweep logic IC the last time my 465
>> broke. About 60.00 plus frt. Grrr.
>>
>> Mark Z.
>>
>>
>
> IIRC,that is cheaper than TEK sold it(new stock).
> 155-0049-02,right?

Don't remember the part number...

>
> What I wonder is where all the stock TEK had on hand went to when they
> made
> the 400 series obsolete? TEK's Recycling store?
>
> I know some small part of it went to an employee instead of the trash
> where
> it was supposed to go. TEK throws out a lot of old parts(instead of
> "close-out" batch-selling them to 3rd parties),and takes a tax writeoff on
> them.
> But I knew one guy who instead had it all boxed up and took it home,after
> one Service Center bench stock purge.
> If I had tried that,I'd have been fired.

Or arrested...

>
> --
> Jim Yanik
> jyanik
> at
> localnet
> dot com

Just a quick note to thank you for your help and interesting comments,
history, etc.

Mark Z.

== 1 of 2 ==
Date: Tues, Aug 30 2011 6:18 pm
From: The Ghost In The Machine

On Aug 30, 4:03 pm, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:
> On Tue, 30 Aug 2011 12:18:02 -0700, DaveC <inva...@invalid.net> wrote:
> >The only Telemecanique products I've been able to find are full-size magnetic
> >starters (contactors).
>
> Ignore the troll.
>
> >I'm looking for a manual start/stop switch with 2-pole contactor built-in.
> >Pressing the start button manually closes the contacts and energizes a coil,
> >which holds the contacts closed. Power fail opens the contacts.
>
> >Small (micro!) is what I'm looking for. No larger than the size of a
> >start/stop switch without contactor.
>
> These are sometimes called "magnetic start switches" and are commonly found on
> larger woodworking tools. I don't know if they're small enough for you but:http://www.grizzly.com/search/search.aspx?q=power%20switch

........SHUT UP ASS DROOL.......I OWED YOU THAT!
AS FOR A P/N DAVE I DO NOT WORK FOR THEM...CONTACT THE CO's I
PROVIDED...THEY COME HIGHLY RECOMMENED FOR SWITCHES ETC.
WHATS NEXT?
COME OVER & INSTALL IT? BOOWAHAHAHAHA, NO WAY JOSÈ!
I AM A GHOST AND DO NOT DO MANUAL LABOR, BUT MAYBE KRAWFISHRW IS
WILLING TO COMPLETE THE JOB FOR YOU.
ASK HIS SQUALID ASS TO HELP YOU GET IT & HELP US KEEP THE INTERNET
FOOL FREE, ITS A GOOD COMBO.
ANYTIME OF THE VIRTUAL NIGHT OR DAY.
++BEST WISHES++
PATECUM
TGITM

== 2 of 2 ==
Date: Tues, Aug 30 2011 6:26 pm
From: "krw@att.bizzzzzzzzzzzz"

On Tue, 30 Aug 2011 18:18:28 -0700 (PDT), The Ghost In The Machine
<proteusiiv@gmail.com> wrote:

>On Aug 30, 4:03 pm, "k...@att.bizzzzzzzzzzzz"
><k...@att.bizzzzzzzzzzzz> wrote:
>> On Tue, 30 Aug 2011 12:18:02 -0700, DaveC <inva...@invalid.net> wrote:
>> >The only Telemecanique products I've been able to find are full-size magnetic
>> >starters (contactors).
>>
>> Ignore the troll.
>>
>> >I'm looking for a manual start/stop switch with 2-pole contactor built-in.
>> >Pressing the start button manually closes the contacts and energizes a coil,
>> >which holds the contacts closed. Power fail opens the contacts.
>>
>> >Small (micro!) is what I'm looking for. No larger than the size of a
>> >start/stop switch without contactor.
>>
>> These are sometimes called "magnetic start switches" and are commonly found on
>> larger woodworking tools. I don't know if they're small enough for you but:http://www.grizzly.com/search/search.aspx?q=power%20switch
>
>........SHUT UP ASS DROOL.......I OWED YOU THAT!
>AS FOR A P/N DAVE I DO NOT WORK FOR THEM...CONTACT THE CO's I
>PROVIDED...THEY COME HIGHLY RECOMMENED FOR SWITCHES ETC.
>WHATS NEXT?
> COME OVER & INSTALL IT? BOOWAHAHAHAHA, NO WAY JOSÈ!
>I AM A GHOST AND DO NOT DO MANUAL LABOR, BUT MAYBE KRAWFISHRW IS
>WILLING TO COMPLETE THE JOB FOR YOU.
> ASK HIS SQUALID ASS TO HELP YOU GET IT & HELP US KEEP THE INTERNET
>FOOL FREE, ITS A GOOD COMBO.
>ANYTIME OF THE VIRTUAL NIGHT OR DAY.
>++BEST WISHES++

At least DaveC now knows what you are.

>PATECUM

Still eating that stuff Queerjano.

>TGITM

I told you a long time ago, Queerjano, penicillin will do wonders for that.

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