sci.electronics.repair - 25 new messages in 9 topics - digest

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

sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: Gm auto radio swap problems
http://groups.google.com/group/sci.electronics.repair/t/e773cc257f7237ed?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Jul 16 2010 8:16 am
From: "William R. Walsh"

Hi!

> The dealer tells me that junk yard radios will not work as they go into
> theft mode as soon as you remove them from the vehicle. If that is
> so why didn't my original radio do this when I removed it and reinstalled it
> numerous times?

The dealer doesn't know what they are talking about, and they are
mixing things up. Collectively, GM refers to all of these systems as
TheftLock (except the earliest one, which is called Delco Loc II.) I
don't know if there was a Delco Loc I or not.

Early Delco Loc and TheftLock radios could or did have a code in place
that would have to be entered if the radio lost power.

The later radios, such as your 2000 model use a different approach. A
small EEPROM on the board holds a copy of the VIN (along with other
parameters) and this is checked over the CAN bus with what is stored
in another computer. If the two do not match--or if there is no
response from the CAN bus, as there would not be if you were bench
testing the radio--the unit will not power up or display anything
other than the clock.

There are a few solutions:

1. Install an aftermarket radio.
2. Pay the dealership what they want to program the new radio.
3. Open the radio up, locate the EEPROM that stores the VIN and
disconnect it. This will cause the radio to report things such as "CAL
error" and complain, but it will work normally otherwise. This is
somewhat difficult because GM house-numbered *everything* in these
radios, even common parts like the EEPROM.

Some parts have their normal numbers, but many do not. There are some
equivalency tables on the web that you might find.

On many of these, pushing several of the front buttons at once will
result in the radio powering up and running despite TheftLock. I
suspect this is a diagnostic test mode, though the set operates
normally. However, late model (2006 and later for sure) radios have a
time-out, after which they will shut off. The one from my 2003 S-10
played for hours this way, so I don't think it does.

William

== 2 of 2 ==
Date: Fri, Jul 16 2010 8:49 am
From: klem kedidelhopper

On Jul 16, 11:16 am, "William R. Walsh" <wm_wa...@hotmail.com> wrote:
> Hi!
>
> > The dealer tells me that junk yard radios will not work as they go into
> > theft mode as soon as you remove them from the vehicle. If that is
> > so why didn't my original radio do this when I removed it and reinstalled it
> > numerous times?
>
> The dealer doesn't know what they are talking about, and they are
> mixing things up. Collectively, GM refers to all of these systems as
> TheftLock (except the earliest one, which is called Delco Loc II.) I
> don't know if there was a Delco Loc I or not.
>
> Early Delco Loc and TheftLock radios could or did have a code in place
> that would have to be entered if the radio lost power.
>
> The later radios, such as your 2000 model use a different approach. A
> small EEPROM on the board holds a copy of the VIN (along with other
> parameters) and this is checked over the CAN bus with what is stored
> in another computer. If the two do not match--or if there is no
> response from the CAN bus, as there would not be if you were bench
> testing the radio--the unit will not power up or display anything
> other than the clock.
>
> There are a few solutions:
>
> 1. Install an aftermarket radio.
> 2. Pay the dealership what they want to program the new radio.
> 3. Open the radio up, locate the EEPROM that stores the VIN and
> disconnect it. This will cause the radio to report things such as "CAL
> error" and complain, but it will work normally otherwise. This is
> somewhat difficult because GM house-numbered *everything* in these
> radios, even common parts like the EEPROM.
>
> Some parts have their normal numbers, but many do not. There are some
> equivalency tables on the web that you might find.
>
> On many of these, pushing several of the front buttons at once will
> result in the radio powering up and running despite TheftLock. I
> suspect this is a diagnostic test mode, though the set operates
> normally. However, late model (2006 and later for sure) radios have a
> time-out, after which they will shut off. The one from my 2003 S-10
> played for hours this way, so I don't think it does.
>
> William

I thought about the possibility of removing the eeprom but I would
first have to buy the radio and then start screwing around with a
circuit board that like you said we don't know where this part is and
I would not have a schematic for. I might actually pick on the wrong
smt and then what? It's a long shot at best and seems like expense in
time money and more frustration. I guess that I'll abandon this idea
and just take the one out of my 1990. I know that I can simply apply
12V to it and it will come alive, like things were meant to. Thanks
for all the information. It was a real education. Lenny.

==============================================================================
TOPIC: Cheap Nike Shox NZ Shoes Nike Air Force One Shoes Nike DUNK SB Shoes
Wholesale free Shipping <PayPal Payment>(http://www.24hoursneakers.com/)
http://groups.google.com/group/sci.electronics.repair/t/80a5d5fa5f147853?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Jul 16 2010 8:28 am
From: huang

Are you searching for good quality and low price products?our company
want to be you reliable supplier in china,we offer brand
shoes,bags,jeans,clothes,we accept a variety of payment
methods .Convenient for you the more you order the better price for
you! if you interested in our goods,pls don't hestate to contact me
Our website (http://www.24hoursneakers.com/)
◥█▄▃▁
...◥█☆█▅▄▃▁▁▁▁▁▁▁▃▄▅︿@︿▅▄▁
〓▇████Ship Wholesaler█████████████▅▄▃▁▁
〓〓〓█████████████

Nike Shox NZ Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox OZ Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox TL1 Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox TL3 Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox R2 Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox R3 Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox R4 Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox R5 Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox Monster Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Shox Torch Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Air Rift Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike DUNK SB Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Air Force One Shoes Wholesale(http://www.24hoursneakers.com/)
(PayPal Payment)
Nike Free Shoes Wholesale(http://www.24hoursneakers.com/) (PayPal
Payment)

==============================================================================
TOPIC: Where to get schematic of Funai TV, Model FT1371?
http://groups.google.com/group/sci.electronics.repair/t/f75b6f935b5d3675?hl=en
==============================================================================

== 1 of 3 ==
Date: Fri, Jul 16 2010 8:30 am
From: Robert Macy

On Jul 15, 11:31 pm, Mike WB2MEP <michael.w.appenzel...@lmco.com>
wrote:
> On Jun 29, 3:30 pm, Robert Macy <m...@california.com> wrote:
>
> > Anybody got one lying around?
>
> > Or at least covering the PCB on the back of the CRT neck?
>
> Sams Photofact #3983.
>
> www.samswebsite.com
>
> Mike WB2MEP

Thank you. Didn't think of that at all!

Oddly, the website won't come in. Even if I do a search for Sams
photofacts index and click on selecting same address with /index etc
that doesn't come in either? The first is a blank screen for 1 hour,
the second is an hour glass cursor on the google search page for an
hour

Are they that busy?

== 2 of 3 ==
Date: Fri, Jul 16 2010 8:51 am
From: Robert Macy

nevermind, the problem was something about out of date security
registration, just took a long time before my browser asked whether I
would accept anything form this site, not a bad shield, eh?

== 3 of 3 ==
Date: Fri, Jul 16 2010 9:06 am
From: Robert Macy

Thanks again Mike

Found #3983, with tax, around $24 !!!!

Considering the original TV was $60 and I could take this TV to a
recycling center to obtain $5, that hurts.

What amazed me was that Funai customer service didn't even keep/offer
a digital form of schematic. Keeping the TV in front of our face
would be like advertising their name, but they don't support before
2003. Now, they've lost an opportunity and irritated a customer

In contrast, I was just talking with the owner of a successful firm
located in Florida. He proudly supports EVERYTHING they have sold
since 1985! Believe me, that committment has won him some contracts
and large follow-on orders from customers.

==============================================================================
TOPIC: 60/40 vs. 63/37 Solder
http://groups.google.com/group/sci.electronics.repair/t/4620260930cd06a7?hl=en
==============================================================================

== 1 of 10 ==
Date: Fri, Jul 16 2010 8:33 am
From: Jeff Liebermann

On Thu, 15 Jul 2010 10:31:05 -0700, "Robbie Hatley"
<see.my.sig@for.my.contact.info> wrote:

>Rosin flux can be removed with 99pct isopropyl alcohol ($1 a bottle at your
>corner drug store).

I prefer the hardware store stuff in the metal cans:
<http://www.acehardware.com/product/index.jsp?productId=3958489>
More expensive but always 99% (ignoring what moisture it absorbs from
the air).

>But frankly, I recommend NOT removing the rosin flux
>scum. Leave it on; it's inert, airproof, waterproof, sweatproof, so it protects
>the joint.

I have some rolls of solder around the shop that are not well labeled
or identified. Rather than risk leaving corrosive flux on a board, I
prefer to clean most everything.

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

== 2 of 10 ==
Date: Fri, Jul 16 2010 8:53 am
From: zekfrivo@zekfrivolous.com (GregS)

In article <i1ovm1$ccb$1@news.eternal-september.org>, "William Sommerwerck" <grizzledgeezer@comcast.net> wrote:
>>>>> The only reason 60/40 was ever manufactured in the first place is
>>>>> that tin is more expensive than lead, so 63/37 solder costs more.
>
>>>> Cite, please? (and I don't mean a link to commodity prices)
>
>>> I can only cite "common sense". 63/37 has always been
>>> more-expensive than 60/40.
>
>> Then you can't substantiate your contention that 60/40 was THE
>> worldwide standard for tens of years just because it was a few pennies
>> cheaper per pound? That is the statement of yours with which I take issue.
>
>I have no objection to your objection.
>
>However, 60/40 was never, ever, "a few pennies per pound" cheaper than
>63/37. For the last 30 years, the price of eutectic solder has been
>sufficiently higher to make one think twice before buying it. The last time
>I purchased solder, I decided that a one-pound roll of Kester 44 would last
>the rest of my life, and I splurged. (At this point in my life, my
>prediction is coming true. I rarely solder any more. If I drop dead, someone
>digging through the junk will find a pleasant surprise. Assuming they know
>what 63/37 is.)
>
>I just checked Parts Express, and a 1# roll of Kester 44 60/40 is $22.23.
>63/37 is $26.85. That's a $4.62 difference, almost 21% more -- hardly
>"pennies per pound". When I bought the same product some years back, my
>memory is that the price was around $7.50 for the 60/40, $9 for the 63/37.
>Even that wasn't "pennies per pound".
>
>I looked at the MCM site for Ersin products. Get this... MCM describes its
>house brand of 60/40 solder as "provid[ing] the lowest possible melting
>point".
>
>Businesses almost always try to cut every corner they can. If you think your
>solderers -- or soldering machines -- are doing a good job, you might prefer
>to buy the less-expensive 60/40.
>
>When I worked at Bendix Field Engineering, I often walked through the
>section where a bunch of women (never men) soldered assemblies, following
>NASA standards. I never thought to ask whether they used 60/40 or 63/37.

I like 63/37 because some stuff I do I like it as low a temp as possible.

Deja vu. I worked for BFEC at NASA site, and went to NASA ssoldering school.
I would guess 60/40 would be the norm.

greg

== 3 of 10 ==
Date: Fri, Jul 16 2010 8:56 am
From: Jeff Liebermann

On Thu, 15 Jul 2010 13:06:03 -0700, dplatt@radagast.org (Dave Platt)
wrote:

>
>>Why are there these two very similar solders? Is there any situation
>>where one is better than the other?
>>
>>I understand the eutectic nature of 63/37, and I wonder if/when 60/40
>>might ever be better to use.
>
>My understanding is that 60/40 has somewhat better wetting properties
>than 63/37, at least with some contact materials. Some people prefer
>it for that reason.
>
>63/37 makes a sharp transition between liquid state and solid state at
>a single, well-defined temperature. 60/40 goes through a transition
>between these two states over a significant range of temperature - in
>between the fully-solid and fully-liquid states it can have a somewhat
>mushy texture. Some people feel that 60/40 brings with it a somewhat
>higher risk of creating a "cold" solder joint (inadequate fusion with
>the contact surfaces) if the joint is moved or stress while the solder
>is dropping through its mushy-state temperature region.

True. 60/40 goes through a semi-molten, plastic-like state, while
63/37 goes instantly from liquid to solid. The joint is not
mechanically solid in this plastic state. It's not an issue with tiny
components, that cool down rather rapidly. However, large components,
that retain more heat, can product "cold" solder joints if moved while
in the is plastic state.

In some cases, this plastic state is desireable. For example,
pre-RoHS plumbers solder was 50/50 for both low cost and the ability
to remain workable over a wider range of temperatures.
<http://www.chemguide.co.uk/physical/phaseeqia/snpb.html>

<http://en.wikipedia.org/wiki/Solder>
This got my attention:
Some alloys, namely of lead and to some degree tin, contain small
but significant amounts of radioisotope impurities. The
radioisotopes undergoing alpha decay are a concern due to their
tendency to cause soft errors. Polonium-210 is especially
problematic; lead-210 beta decays to bismuth-210 which then beta
decays to polonium-210, an intense emitter of alpha particles.
Uranium-238 and thorium-232 are other significant contaminants of
lead containing alloys.
Oh swell.... something else to worry about.

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

== 4 of 10 ==
Date: Fri, Jul 16 2010 9:47 am
From: "William Sommerwerck"

> I like 63/37 because some stuff I do I like it as low a temp
> as possible.

Allmost all my soldering is repairs; cold joints seem more likely when
you're fixing something.

> Deja vu. I worked for BFEC at NASA site, and went to NASA
> soldering school. I would guess 60/40 would be the norm.

Probably. I never had to solder, so I never went to school.

Which site? When? I worked from 1974 through 1978.

== 5 of 10 ==
Date: Fri, Jul 16 2010 11:42 am
From: zekfrivo@zekfrivolous.com (GregS)

In article <6737aa54-c264-4d4f-8dbf-86db5a76ba1f@q22g2000yqm.googlegroups.com>, George Herold <ggherold@gmail.com> wrote:
>On Jul 15, 3:40=A0pm, zekfr...@zekfrivolous.com (GregS) wrote:
>> In article <7a307a68-f754-413e-8113-4b9d0ce7a...@c10g2000yqi.googlegroups=
>..com>, George Herold <ggher...@gmail.com> wrote:
>>
>>
>>
>>
>>
>> >On Jul 15, 11:42=3DA0am, John Larkin
>> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> >> On 15 Jul 2010 08:04:55 GMT, John Doe <j...@usenetlove.invalid> wrote:
>>
>> >> >none given.now (Joe) wrote:
>>
>> >> >> Why are there these two very similar solders? =3DA0Is there any
>> >> >> situation where one is better than the other? =3DA0
>>
>> >> >Dunno, but... If you do detail work, try water-soluble flux
>> >> >solder. You just wipe off the residue for a sparkling clean
>> >> >circuit.
>>
>> >> And one that makes a great humidity sensor.
>>
>> >> John
>>
>> >Yeah, My prototype of a board with several high meg resistors (up to 1
>> >gig.) was put together by myself with old Kester "44" (rosin flux.)
>> >Worked great. =A0Production did a few with their favorite water based
>> >flux... No good! =A0Now I have to convince them to go back to the old
>> >standard. =A0 The new ROHS fluxes seem to be even worse. =A0I measured a
>> >few meg ohms between pads that had been 'cleaned'.... NOT.
>>
>> I had a lot of problems with high Z circuitry. Got under the pads.
>> Some boards I had to clean/dry 10 times. In the interim, some of the clea=
>ner
>> I used got into some caps and started their own circuit mess.
>>
>> greg- Hide quoted text -
>>
>> - Show quoted text -
>
>What kind of flux were you using? I want to try some tests, just
>laying down solder and flux gobs on 0805 SMD pads and measure the
>resistance. Then cleaning and remeasuring. (I've got a bunch of
>other 'fires' that I'm putting out so this may be a few days.)
>

The boards were commercially made with water based flux.
I had to fix them. They actually laid out the boards, which was a mistake.

greg

== 6 of 10 ==
Date: Fri, Jul 16 2010 11:43 am
From: zekfrivo@zekfrivolous.com (GregS)

In article <i1q2fa$nr9$1@news.eternal-september.org>, "William Sommerwerck" <grizzledgeezer@comcast.net> wrote:
>> I like 63/37 because some stuff I do I like it as low a temp
>> as possible.
>
>Allmost all my soldering is repairs; cold joints seem more likely when
>you're fixing something.
>
>
>> Deja vu. I worked for BFEC at NASA site, and went to NASA
>> soldering school. I would guess 60/40 would be the norm.
>
>Probably. I never had to solder, so I never went to school.
>
>Which site? When? I worked from 1974 through 1978.
>
>

http://zekfrivolous.com/goldstone/

== 7 of 10 ==
Date: Fri, Jul 16 2010 11:49 am
From: Fred Abse

On Thu, 15 Jul 2010 23:53:31 -0700, William Sommerwerck wrote:

> When I worked at Bendix Field Engineering, I often walked through the
> section where a bunch of women (never men) soldered assemblies, following
> NASA standards. I never thought to ask whether they used 60/40 or 63/37.

NASA standards authorize both.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)

== 8 of 10 ==
Date: Fri, Jul 16 2010 11:59 am
From: "William Sommerwerck"

>> Which site? When? I worked from 1974 through 1977.

> http://zekfrivolous.com/goldstone

Did you ever change the klystron frequency from the control panel (there
were six buttons along the bottom), rather than going out to the
transmitter? If so, you used one of the improvements I installed.

== 9 of 10 ==
Date: Fri, Jul 16 2010 12:19 pm
From: "Robbie Hatley"

"GregS" recommends for flux removal:

> If you can get 95% ethanol, I thinks its best. By the time
> you use 98 or 99% it absorbs water anyway on the board,
> and you still have a water residue. You can also drink it.

And then you accidentally plug the 120VAC into the 5VDC output of
a voltage regulator, which promptly explodes and emits flames and
smoke, and you just have time to say "oh wow, man, pretty fireworks"
before the lights go out and the boss comes storming in saying "What the
hell is going on in here? Why is that circuit board flaming like that?
Someone grab the fire extinguisher!" Yep, ethanol works wonders,
but it's probably not best for job security. I think I'll stick with the
isopropanol.

== 10 of 10 ==
Date: Fri, Jul 16 2010 1:14 pm
From: zekfrivo@zekfrivolous.com (GregS)

In article <i1qa75$p2m$1@news.eternal-september.org>, "William Sommerwerck" <grizzledgeezer@comcast.net> wrote:
>>> Which site? When? I worked from 1974 through 1977.
>
>> http://zekfrivolous.com/goldstone
>
>Did you ever change the klystron frequency from the control panel (there
>were six buttons along the bottom), rather than going out to the
>transmitter? If so, you used one of the improvements I installed.

I never ran that, but do recall them tuning them up. Something
rings a bell though about mods. As the 80's rolled through everything
was remote controled off site.

I do remember the time I pushed a button on one of the antenna motors,
and everything went black for miles.

I also remember the time one would go outside and point at the falling Skylab,
and the other person would try to move the antenna and lock on to it.
What with the 1 degree beamwidth was impossible. We were using Norads
predicts and they were too far off to be able to use. Somebody finally locked
onto the spacecraft and finally got good predicts.

I also remember the time we tracked the moon with a wrench.
For a while.

Big 85 ft.antenna made in Pittsburgh, as was much of the stuff made in the USA
back then.

greg

==============================================================================
TOPIC: PowerWare 9110 UPS schematic??
http://groups.google.com/group/sci.electronics.repair/t/8b7a20f044b334c4?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Jul 16 2010 8:42 am
From: "Jack"

"PeterD" <peter2@hipson.net> wrote in message
news:cah04694lcguk9vcbh47buil6o5ues0sqf@4ax.com...
> On Fri, 16 Jul 2010 07:43:46 +0300, "Jack"
> <jankroPOISTA@dnainternet.net> wrote:
>
>>No, I do not have manual for it and I have not been able to find one with
>>Google.
>>I sent e-mail to Eaton's technical support without success. Eaton's pages
>>or
>>search do not have any info on the 9110 -series UPS.
>>
>>-Jan
>>
>
> Google returns a number of hits for manuals. This unit seems to be
> export only for Asia.
>
> With the unit powered up, press and hold the power on switch/button
> for about 5 seconds, and see if that powers it on.
>

Found the problem!

Someone (probably when cleaning the unit) had flipped the flat cable running
to the control panel 180 deg.!
Another words, no.1 pin was not no.1. pin anymore! The flat cable connector
is keyed in one end, but not in the control panel end. I flipped the cable
around and now it works fine.

Thanks for everyone that gave their help!

-Jan

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

==============================================================================
TOPIC: Thinking about the good old days.
http://groups.google.com/group/sci.electronics.repair/t/baa1b072143ae852?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Jul 16 2010 10:41 am
From: "ian field"

http://www.vintage-radio.info/llj/

==============================================================================
TOPIC: Telephone wiring 101.
http://groups.google.com/group/sci.electronics.repair/t/c2d228c87bcf04bd?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Jul 16 2010 1:54 pm
From: "Robbie Hatley"

David Farber, regarding your phone wiring confusions, I have some comments.

Firstly, what is a "splitter"? That's not any kind of electronic component I've
ever heard of. Is is a multiplexer? A joint? A wire-pairs separater? Or
something else completely? Try checking it with an ohmmeter, or read the
manual if you have one, to find out what it really is.

Secondly, yes, polarities often get switched in phone wiring, sometimes
*several* times between the service entry and the telephone. (Obviously,
if the number of swaps is odd, the polarity will be wrong on other end.)

Thirdly, don't trust wire colors, those change too, sometimes *several*
times between the service entry and the telephone. (This, and the
polarity swapping, are because phone cables tend to be "dropped" from
the attic into the walls as separate snippets, and pasted together in the
attic. So a blue/white pair from the entry might become orange/white,
then green/white, then white/purple by the time it gets to your phone.

Fourthly, don't assume that because you get a dial tone, you have the
wire-pair you think you do. Call your own phone number. If it
rings, you do *not* have the right wire pair! You're illegally stealing
service from someone else instead. Instead, try other pairs until you
find the pair and polarity that not only gives a dial tone, but also gives
a BUSY SIGNAL when you dial your own number. That's your pair.
This is especially true in apartment buildings and businesses, but can
even be a problem in single-family homes, if multiple lines (some
possibly no longer in use) are installed.

Once I accidentally tapped into a pay phone that way at my apartment
building. Since the service entry is in the rear, and the pay phone is
out front, the installers ran the wires through my bedroom. Interestingly,
I was able to make phone calls without paying the $0.75 the pay phone
normally charges. I disconnected it immediately, though, both to stay out
of trouble, and because it wasn't the line my DSL was coming in on.

--
Cheers,
Robbie Hatley
lonewolf [[at]] well [[dot]] com

==============================================================================
TOPIC: Microwave advice
http://groups.google.com/group/sci.electronics.repair/t/cf0cdf1a15cc7e64?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Jul 16 2010 2:47 pm
From: "Mr. Land"

OK, I see there is a long history of microwave over repair questions.
But I don't seem to see a thread that has my question:

So I have an older GE JVM1190 over-the-stove microwave unit.

Symptom is no heat.

When powered up and programmed to cook, the unit makes the expected
humming noise (the same it's always made) but a cup of water in the
chamber will not heat up.

I've studied the microwave FAQ repeatedly and I believe I understand
the dangers.

I constructed a long wooden-stick-based discharger for the HV cap,
discharged it (didn't get any spark at all), then ensured there was no
residual voltage on either of its terminals. Then I shorted the
terminals.

First I "tested" the magnetron: infinite resistance from either
cathode connection pin to ground, very low resistance between the two
pins themselves. Seems OK.

Then I tested the HV diode by placing it series with a 390 ohm
resistor and applying 15 VDC, and meauring the voltage drop across the
device. -15V negative biased, about 10 VDC forward biased...this
seemed to be within range.

Finally I tested the HV cap. It reads infinite resistance to the
chassis from either terminal. Between the terminals my capacitance
meters reads around 0.86 uF... which seems to be correct.

I've heard mention of a possibly bad HV fuse. AFAICT, this unit
doesn't have one of those.

So...the HV cap seems good, the mag seems good, the diode seems good,
the unit seems to draw appropriate current when in cook mode,yet the
over won't heat food.

What am I missing???

Could the magnetron still be "bad" despite the fact that it doesn't
read shorted/open?

Thanks.

== 2 of 2 ==
Date: Fri, Jul 16 2010 4:04 pm
From: Cydrome Leader

Mr. Land <graftonfot@yahoo.com> wrote:
> OK, I see there is a long history of microwave over repair questions.
> But I don't seem to see a thread that has my question:
>
> So I have an older GE JVM1190 over-the-stove microwave unit.
>
> Symptom is no heat.
>
> When powered up and programmed to cook, the unit makes the expected
> humming noise (the same it's always made) but a cup of water in the
> chamber will not heat up.
>
> I've studied the microwave FAQ repeatedly and I believe I understand
> the dangers.
>
> I constructed a long wooden-stick-based discharger for the HV cap,
> discharged it (didn't get any spark at all), then ensured there was no
> residual voltage on either of its terminals. Then I shorted the
> terminals.
>
> First I "tested" the magnetron: infinite resistance from either
> cathode connection pin to ground, very low resistance between the two
> pins themselves. Seems OK.
>
> Then I tested the HV diode by placing it series with a 390 ohm
> resistor and applying 15 VDC, and meauring the voltage drop across the
> device. -15V negative biased, about 10 VDC forward biased...this
> seemed to be within range.
>
> Finally I tested the HV cap. It reads infinite resistance to the
> chassis from either terminal. Between the terminals my capacitance
> meters reads around 0.86 uF... which seems to be correct.
>
> I've heard mention of a possibly bad HV fuse. AFAICT, this unit
> doesn't have one of those.
>
> So...the HV cap seems good, the mag seems good, the diode seems good,
> the unit seems to draw appropriate current when in cook mode,yet the
> over won't heat food.
>
> What am I missing???
>
> Could the magnetron still be "bad" despite the fact that it doesn't
> read shorted/open?
>
> Thanks.

Is the transformer secondary good? check its resistance from the HV
terminal to the chassis. Open = bad.

Is that microwave old enough to use a reed relay for defrost mode?

Do you have a way to measure the HV from a microwave oven safely?

==============================================================================
TOPIC: Weird telephone problem
http://groups.google.com/group/sci.electronics.repair/t/5b67728e19c05524?hl=en
==============================================================================

== 1 of 4 ==
Date: Fri, Jul 16 2010 2:54 pm
From: David Nebenzahl

(And by telephone I mean the kind God intended us to use, a regular old
land line, not those Dick Tracy cell-phone thingies.)

Client has a bunch of phones in their house. Starting a few days ago,
several of them don't work; pick them up, no dial tone. (Confirmed with
a good set which I used to test all the jacks.)

But get this: while I was there, at least one of the phones that doesn't
work (a wireless phone) rang on an incoming call. WTF?!?!? It rang, but
when picked up--nothing, dead. No dial tone trying to make a call.

Anyone familiar with the inner mysteries of the telephone system care to
try to 'splain this? How could a phone not work, but still ring on an
incoming call?

--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

== 2 of 4 ==
Date: Fri, Jul 16 2010 2:57 pm
From: David Nebenzahl

On 7/16/2010 2:54 PM David Nebenzahl spake thus:

> Anyone familiar with the inner mysteries of the telephone system care to
> try to 'splain this? How could a phone not work, but still ring on an
> incoming call?

Forgot to mention, in case it's relevant, that they also have DSL, and
some of the phones have in-line DSL filters. Problem remains with or
without the filters.

--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

== 3 of 4 ==
Date: Fri, Jul 16 2010 3:21 pm
From: dplatt@radagast.org (Dave Platt)

In article <4c40d4c0$0$2401$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

>Client has a bunch of phones in their house. Starting a few days ago,
>several of them don't work; pick them up, no dial tone. (Confirmed with
>a good set which I used to test all the jacks.)
>
>But get this: while I was there, at least one of the phones that doesn't
>work (a wireless phone) rang on an incoming call. WTF?!?!? It rang, but
>when picked up--nothing, dead. No dial tone trying to make a call.
>
>Anyone familiar with the inner mysteries of the telephone system care to
>try to 'splain this? How could a phone not work, but still ring on an
>incoming call?

That sounds to me as if the circuit has developed a "DC open", which
still has some small amount of capacitive coupling through it.

The central office won't "see" that the phones have gone off-hook, and
initiate a dial tone, unless the phone draws at least a few milliamps
of DC current from the line. If corrosion or a wire break has
interrupted one side or the other of the line, the phone wouldn't be
able to draw DC current through it, and wouldn't trigger the off-hook
detector at the central office.

Ringing is a different issue, as it involved higher voltages, AC (or
pulsed-DC), and is handled differently by different sorts of phones.
The ringing signal here in the U.S. is somewhere around 100 volts at
20 Hz, if I recall correctly. Real old-fashioned phones with real
ringers have an electromagnet/solenoid ringer, coupled to the line via
a large-value capacitor (agian, if I recall correctly) and they
require a significant amount of ringer current to operate.

Phones with electronic ringers... and wireless phones in particular...
operate differently. They really don't need to draw much current from
the ringing line in order to detect a ring... all a wireless-phone
base station may need to do is monitor the phone-line voltage with a
high-impedance voltage sensor, and "tell" the handsets to ring when it
sees a high voltage.

My guess is that: (1) you've got a broken wire or corroded connection
in the path which feeds the phones that no longer work, and (2)
there's enough leakage through the break to allow the wireless handset
to detect the high-voltage AC which means "ringing". Hence, the
wireless handset is told to ring. However, when you try to answer the
call, the wireless station base tries to connect to the line and start
drawing the normal amount of loop current... and it can't do so
because of the near-total break in the wire.

Try using one of those red-and-green-LED "phone line voltage and
polarity" detectors. I suspect you'll find that it doesn't light
(either color) when plugged into one of the dead outlets, but that if
you phone the house number from outside the LED will flash at least
slightly due to a small amount of AC leakage past the broken connection.

Start looking for bad splices, broken wires in junction boxes, or
places where rats or mice have chewed on the wiring.

--
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!

== 4 of 4 ==
Date: Fri, Jul 16 2010 4:36 pm
From: Bill Janssen

Dave Platt wrote:
> In article <4c40d4c0$0$2401$822641b3@news.adtechcomputers.com>,
> David Nebenzahl <nobody@but.us.chickens> wrote:
>
>
>> Client has a bunch of phones in their house. Starting a few days ago,
>> several of them don't work; pick them up, no dial tone. (Confirmed with
>> a good set which I used to test all the jacks.)
>>
>> But get this: while I was there, at least one of the phones that doesn't
>> work (a wireless phone) rang on an incoming call. WTF?!?!? It rang, but
>> when picked up--nothing, dead. No dial tone trying to make a call.
>>
>> Anyone familiar with the inner mysteries of the telephone system care to
>> try to 'splain this? How could a phone not work, but still ring on an
>> incoming call?
>>
>
> That sounds to me as if the circuit has developed a "DC open", which
> still has some small amount of capacitive coupling through it.
>
> The central office won't "see" that the phones have gone off-hook, and
> initiate a dial tone, unless the phone draws at least a few milliamps
> of DC current from the line. If corrosion or a wire break has
> interrupted one side or the other of the line, the phone wouldn't be
> able to draw DC current through it, and wouldn't trigger the off-hook
> detector at the central office.
>
> Ringing is a different issue, as it involved higher voltages, AC (or
> pulsed-DC), and is handled differently by different sorts of phones.
> The ringing signal here in the U.S. is somewhere around 100 volts at
> 20 Hz, if I recall correctly. Real old-fashioned phones with real
> ringers have an electromagnet/solenoid ringer, coupled to the line via
> a large-value capacitor (agian, if I recall correctly) and they
> require a significant amount of ringer current to operate.
>
> Phones with electronic ringers... and wireless phones in particular...
> operate differently. They really don't need to draw much current from
> the ringing line in order to detect a ring... all a wireless-phone
> base station may need to do is monitor the phone-line voltage with a
> high-impedance voltage sensor, and "tell" the handsets to ring when it
> sees a high voltage.
>
> My guess is that: (1) you've got a broken wire or corroded connection
> in the path which feeds the phones that no longer work, and (2)
> there's enough leakage through the break to allow the wireless handset
> to detect the high-voltage AC which means "ringing". Hence, the
> wireless handset is told to ring. However, when you try to answer the
> call, the wireless station base tries to connect to the line and start
> drawing the normal amount of loop current... and it can't do so
> because of the near-total break in the wire.
>
> Try using one of those red-and-green-LED "phone line voltage and
> polarity" detectors. I suspect you'll find that it doesn't light
> (either color) when plugged into one of the dead outlets, but that if
> you phone the house number from outside the LED will flash at least
> slightly due to a small amount of AC leakage past the broken connection.
>
> Start looking for bad splices, broken wires in junction boxes, or
> places where rats or mice have chewed on the wiring.
>
>
Good advice above

I want to add. you should see about 52 Volts on an idle line and 25
milliamp or greater current when off hook
I think to telephone switch will work on 20 milliamp, but that is
pushing it.The voltage isn't critical but the current is

Bill K7NOM

==============================================================================

You received this message because you are subscribed to the Google Groups "sci.electronics.repair"
group.

To post to this group, visit http://groups.google.com/group/sci.electronics.repair?hl=en

To unsubscribe from this group, send email to sci.electronics.repair+unsubscribe@googlegroups.com

To change the way you get mail from this group, visit:
http://groups.google.com/group/sci.electronics.repair/subscribe?hl=en

To report abuse, send email explaining the problem to abuse@googlegroups.com

==============================================================================
Google Groups: http://groups.google.com/?hl=en

Electronics

sci.electronics.repair - 25 new messages in 9 topics - digest

No Response to "sci.electronics.repair - 25 new messages in 9 topics - digest"

Post a Comment

Blog Roll

Blog Archive