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

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

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Today's topics:

==============================================================================
TOPIC: CRT TV repair, power supply defect.
http://groups.google.com/group/sci.electronics.repair/t/d4c2d93f9d169dcb?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Sep 22 2011 12:36 am
From: Franc Zabkar

On Wed, 21 Sep 2011 21:00:20 -0700 (PDT), Vernon Paul
<vernondopaul@gmail.com> put finger to keyboard and composed:

>An update on my repair situation. I decided to follow all the
>instruction gathered here and some from Sam, beginning with the
>easiest first. This is what I got. By reducing the G2 and brightness
>all the way down the TV works fine, no shutdown. Even with a decent
>brightness and G2 cranked up and decent picture available, it does not
>shutdown. However when there is some bright scene there is signs of
>tendency to shutdown. When the the brightness and G2 is cranked up too
>much it shutdowns. The voltages from the power supply seems to be
>stable during the shutdown, not sure about the currents though.
>
> Is the problem more likely in the power supply or deflection side?

Is there an ABL (automatic beam limiter) circuit? I have seen ABL
failures that have caused shutdown.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

==============================================================================
TOPIC: Exploring rotary encoder problems
http://groups.google.com/group/sci.electronics.repair/t/5b678ef9db12089e?hl=en
==============================================================================

== 1 of 3 ==
Date: Thurs, Sep 22 2011 2:47 am
From: "Mark Zacharias"

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:j5c6e0$34i$1@dont-email.me...
> Deeper than just saying clear out the grease. 2 in 2 days, first input
> selector of an amp , not explored in depth, second vol control of a music
> centre.
>
> First had radial contacts that were slightly staggered and the fixed
> contacts were in line , second was exact radial contacts and staggered
> fixed
> contacts. On the second I took some R measurements before and after.
> There are 3 contacts, one common and the other 2 staggered to pick up CW
> or
> CCW rotation. Just measuring between the 2 sense contacts as at some point
> they are cross connected, measured 2.5R each of the posistions but very
> tiny
> position to get this reading. Ladled out and then dissolved the grease,
> reassembled and took readings again . Now 1.5R each bridging posistion
> and
> a lot easier to find that posistion, ie more latitude. I imagine from the
> consistency of the R readings that something to do with deforming or block
> under one of the contacts reducing the contact to a very small area and
> then
> only marginal connection posistion bridging the 2 contacts. I assumed the
> electronic sensing was one line before the other but perhaps duration of
> both contacts on simulataneously, or not, is also something to do with
> normal sensing
>
>

Clean the moving contacts and stationary contact area as you would relay and
switch contacts. Better to replace the control, but this will fix it.

Mark Z.

== 2 of 3 ==
Date: Thurs, Sep 22 2011 4:34 am
From: "N_Cook"

Mark Zacharias <mark_zacharias@labolgcbs.net> wrote in message
news:4e7b0416$0$26397$a8266bb1@newsreader.readnews.com...
> "N_Cook" <diverse@tcp.co.uk> wrote in message
> news:j5c6e0$34i$1@dont-email.me...
> > Deeper than just saying clear out the grease. 2 in 2 days, first input
> > selector of an amp , not explored in depth, second vol control of a
music
> > centre.
> >
> > First had radial contacts that were slightly staggered and the fixed
> > contacts were in line , second was exact radial contacts and staggered
> > fixed
> > contacts. On the second I took some R measurements before and after.
> > There are 3 contacts, one common and the other 2 staggered to pick up CW
> > or
> > CCW rotation. Just measuring between the 2 sense contacts as at some
point
> > they are cross connected, measured 2.5R each of the posistions but very
> > tiny
> > position to get this reading. Ladled out and then dissolved the grease,
> > reassembled and took readings again . Now 1.5R each bridging posistion
> > and
> > a lot easier to find that posistion, ie more latitude. I imagine from
the
> > consistency of the R readings that something to do with deforming or
block
> > under one of the contacts reducing the contact to a very small area and
> > then
> > only marginal connection posistion bridging the 2 contacts. I assumed
the
> > electronic sensing was one line before the other but perhaps duration of
> > both contacts on simulataneously, or not, is also something to do with
> > normal sensing
> >
> >
>
> Clean the moving contacts and stationary contact area as you would relay
and
> switch contacts. Better to replace the control, but this will fix it.
>
> Mark Z.
>

I've never seen a relay with grease it it. Rotary encoders or the BCD type
ones, it is the grease thats the problem but exactly why it is a problem is
still not fathomed. I assume a hardening or accretion process that
eventually wedges under a wiper. Why do they not use "dry lubricant" perhaps
locksmith's graphite as long as in a minute quantity.

== 3 of 3 ==
Date: Thurs, Sep 22 2011 9:18 am
From: "Michael A. Terrell"

N_Cook wrote:
>
> Why do they not use "dry lubricant" perhaps
> locksmith's graphite as long as in a minute quantity.

The grease is needed to prevent metal migration across the open areas
as they slide. I've seen people try to run similar items dry, or with
other crappy lubricants. Graphite would need something to hold it to
the board, and you would need enough that would cause leakage as the
sliding contact compacted it to the surface. Good old fashioned 'GC
Tunerlube' does an excellent job on sliding contacts.

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

==============================================================================
TOPIC: TOP 15 HOT BOLLYWOOD KISSES
http://groups.google.com/group/sci.electronics.repair/t/7255bda9b0db817a?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Sep 22 2011 3:46 am
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==============================================================================
TOPIC: Alliance U100 antenna rotor
http://groups.google.com/group/sci.electronics.repair/t/d0231afb599de425?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Sep 22 2011 5:38 am
From: klem kedidelhopper

On Sep 21, 6:21 pm, "Dave M" <dgminala4...@mediacombb.net> wrote:
> Jerry Peters wrote:
> > klem kedidelhopper <captainvideo462...@gmail.com> wrote:
>
> >> I used to install the Alliance U100 rotors for all my antenna jobs.
> >> These rotors had 4 terminals that connected to the control box. I
> >> just came across an Alliance rotor that looks just like a U100
> >> however it has 5 terminals instead of 4. I have never seen this
> >> model of Alliance rotor before. Does anyone know what the purpose
> >> of the fifth terminal was for and if there is any way that this
> >> rotor could be used with a standard U100 four terminal control box?
> >> Someone else suggested that the fifth terminal was for a similar
> >> system as the U100 but it was solid state. If so, was the solid
> >> state circuitry in the box or the rotor? Because as I remember from
> >> disassembling and repairing some of those, inside the rotor were
> >> just motor windings and a stop switch, I wonder if in fact the
> >> electronics was all in the box and the fifth terminal was just
> >> something to do with the solid state "improvement" to the system,
> >> one could possibly ignore the fifth terminal and just use a standard
> >> U100 ratchet type box? Lenny
>
> > It's not a "stop switch", every time the contacts close, it actuates
> > the solenoid in the control box & advances the dial by 1 detent.
>
> > Jerry
>
> Your 5-terminal rotator unit is likely model C-225. It's definitely a solid
> state control box, and can't be modified to control a U-100 rotor. The
> rotors are different inside; the U-100 rotor having a reversing capacitor
> and the motor, the C-225 having the motor and a position-sensing
> potentiometer.
>
> Go tohttp://bama.edebris.com/manuals/alliance/rotorserviceand download the
> Alliance Antenna Rotor Service Manual and you'll be able to see the details
> of both models, and why they aren't compatible.
>
> --
> David
> dgminala at mediacombb dot net

Thanks very much for that link Dave. I had no idea that Alliance made
so many different types of rotors. In every new antenna installation I
ever did I always used a U100. The funny thing is in all these years
of mixing and matching old four terminal stuff I either picked up or
had lying around I never had a problem getting a box/control combo to
work. But after looking at the schematics I guess I've been extremely
lucky. It's truly a shame they went out of business, They had the best
product for TV in the industry. I never had to climb up on someone's
roof even years later to replace a defective Alliance rotor. The
current Chinese Channel Master is a real POS. I wouldn't even install
one for a customer. Lenny

== 2 of 2 ==
Date: Thurs, Sep 22 2011 9:23 am
From: "Michael A. Terrell"

klem kedidelhopper wrote:
>
> On Sep 21, 6:21 pm, "Dave M" <dgminala4...@mediacombb.net> wrote:
> > Jerry Peters wrote:
> > > klem kedidelhopper <captainvideo462...@gmail.com> wrote:
> >
> > >> I used to install the Alliance U100 rotors for all my antenna jobs.
> > >> These rotors had 4 terminals that connected to the control box. I
> > >> just came across an Alliance rotor that looks just like a U100
> > >> however it has 5 terminals instead of 4. I have never seen this
> > >> model of Alliance rotor before. Does anyone know what the purpose
> > >> of the fifth terminal was for and if there is any way that this
> > >> rotor could be used with a standard U100 four terminal control box?
> > >> Someone else suggested that the fifth terminal was for a similar
> > >> system as the U100 but it was solid state. If so, was the solid
> > >> state circuitry in the box or the rotor? Because as I remember from
> > >> disassembling and repairing some of those, inside the rotor were
> > >> just motor windings and a stop switch, I wonder if in fact the
> > >> electronics was all in the box and the fifth terminal was just
> > >> something to do with the solid state "improvement" to the system,
> > >> one could possibly ignore the fifth terminal and just use a standard
> > >> U100 ratchet type box? Lenny
> >
> > > It's not a "stop switch", every time the contacts close, it actuates
> > > the solenoid in the control box & advances the dial by 1 detent.
> >
> > > Jerry
> >
> > Your 5-terminal rotator unit is likely model C-225. It's definitely a solid
> > state control box, and can't be modified to control a U-100 rotor. The
> > rotors are different inside; the U-100 rotor having a reversing capacitor
> > and the motor, the C-225 having the motor and a position-sensing
> > potentiometer.
> >
> > Go tohttp://bama.edebris.com/manuals/alliance/rotorserviceand download the
> > Alliance Antenna Rotor Service Manual and you'll be able to see the details
> > of both models, and why they aren't compatible.
> >
> > --
> > David
> > dgminala at mediacombb dot net
>
> Thanks very much for that link Dave. I had no idea that Alliance made
> so many different types of rotors. In every new antenna installation I
> ever did I always used a U100. The funny thing is in all these years
> of mixing and matching old four terminal stuff I either picked up or
> had lying around I never had a problem getting a box/control combo to
> work. But after looking at the schematics I guess I've been extremely
> lucky. It's truly a shame they went out of business, They had the best
> product for TV in the industry. I never had to climb up on someone's
> roof even years later to replace a defective Alliance rotor. The
> current Chinese Channel Master is a real POS. I wouldn't even install
> one for a customer. Lenny

I had to, quite a few times to replace the soft seal on rotors that
were 25+ years old. I would pull the rotor, replace the old screws with
stainless, clean and relube the bearings. If it had the open pot to
drive a meter for position I would clean the resistance wire & sliding
contact, and use GC Tunerlube on the wire. Add a new non polar
electrolytic to the control box & replace the old wire between them, and
they would run another 25 years. :)

Some I serviced were so old that they simply had a lamp to tell you
that the rotor was at the end of it's rotation.

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

==============================================================================
TOPIC: CFLs - retrofitting low ESR capacitors
http://groups.google.com/group/sci.electronics.repair/t/4b33f31f667954a0?hl=en
==============================================================================

== 1 of 5 ==
Date: Thurs, Sep 22 2011 6:45 am
From: "Ian Field"

"Dennis" <jon.dough@ithemorgue.com> wrote in message
news:f72dnVWBnKU8F-fTnZ2dnUVZ_gudnZ2d@westnet.com.au...
>
> "Phil Allison" <phil_a@tpg.com.au> wrote in message
> news:9dvbhgFrhaU1@mid.individual.net...
>>
>> "Ian Fuckwit Field"
>>
>>
>>> Last time I looked ..
>>
>>
>> ** Impossible for anyone who has wanked themselves blind to look at
>> anything.
>>
>>
>>
> Bullshit Phil, it's a myth;
>
> http://psychcentral.com/lib/2007/does-masturbation-cause-blindness/

It causes deafness - philthy never listens to anyone.

== 2 of 5 ==
Date: Thurs, Sep 22 2011 9:08 am
From: "Michael A. Terrell"

Ian Field wrote:
>
> "Dennis" <jon.dough@ithemorgue.com> wrote in message
> news:f72dnVWBnKU8F-fTnZ2dnUVZ_gudnZ2d@westnet.com.au...
> >
> > "Phil Allison" <phil_a@tpg.com.au> wrote in message
> > news:9dvbhgFrhaU1@mid.individual.net...
> >>
> >> "Ian Fuckwit Field"
> >>
> >>
> >>> Last time I looked ..
> >>
> >>
> >> ** Impossible for anyone who has wanked themselves blind to look at
> >> anything.
> >>
> >>
> >>
> > Bullshit Phil, it's a myth;
> >
> > http://psychcentral.com/lib/2007/does-masturbation-cause-blindness/
>
> It causes deafness - philthy never listens to anyone.

Loss of blood to the brain, in Phil's case. :(

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

== 3 of 5 ==
Date: Thurs, Sep 22 2011 9:14 am
From: "Michael A. Terrell"

Trevor Wilson wrote:
>
> Michael A. Terrell wrote:
> > Trevor Wilson wrote:
> >>
> >> Michael A. Terrell wrote:
> >>> Trevor Wilson wrote:
> >>>>
> >>>> **I do. I keep track of the life of my lamps. Incandescents don't
> >>>> last long.
> >>>
> >>>
> >>> There are some in the US that have been on 24/7 for decades, and
> >>> still work. Some are over 100 years old.
> >>
> >> **Indeed. The ways to get incandescents to last a long time are well
> >> known. They are simply under-run massively. IOW: Use a 280VAC rated
> >> lamp at 240VAC and the thing will last MUCH longer. Of course,
> >> colour temperature edges much closer towards the red and efficiency
> >> is absolute crap.
> >>
> >> Cheap bulbs don't last,
> >>> and neither do those that are used improperly.
> >>
> >> **Not so different to CFLs and LEDs. Funny about that.
> >
> >
> > Still doesn't prove your lame assed claim that incandescents don't
> > last.
>
> **I don't need to prove it. It has been well documented:
>
> http://www.megavolt.co.il/Tips_and_info/bulbs_at_glance.html
>
> http://en.wikipedia.org/wiki/Compact_fluorescent_lamp#Lifespan
>
> http://www.designrecycleinc.com/led%20comp%20chart.html
>
> http://www.gelighting.com/eu/resources/firstlight/module04/08.html
>
> http://en.wikipedia.org/wiki/Lamp_rerating
>
> This is an interesting primer on the topic:
>
> http://donklipstein.com/bulb1.html

You can find websites that say anything you want them to. I do use
some CFLs where I don't have to stay for more than a few minutes and I
despise them. "DO NOT USE BASE UP!!!" That eliminates a lot of
fixtures. "DO NOT USE IN AN ENCLOSED SPACE!!!" There goes the outdoor
lights. I do not like the color temperature of CFLs, or a lot of other
light sources. LED Lights give me headaches. Go preach to your choir of
greenies.

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

== 4 of 5 ==
Date: Thurs, Sep 22 2011 9:17 am
From: Jim Yanik

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:b6veq.4435$4%.1004@newsfe18.ams2:

>
>
> "Phil Allison" <phil_a@tpg.com.au> wrote in message
> news:9dsttbF2n3U1@mid.individual.net...
>>
>> "Arfa Daily"
>> "Trevor Wilson"
>>>
>>> <snip>
>>>>
>>>> * LEDs use a miniscule amount of silicon.
>>>> * Incandescent lamps use a very large amount of silicon
>>>
>>> Whereabouts ?
>>
>>
>> ** The TW charlatan is being a real clever dick.
>>
>> Glass is about 23% silicon by weight.

glass is ~75% silicon dioxide.

compare a lamp envelope to a LED silicon substrate,and there's no doubt
about which has more silicon. At least to the rational folks.
>
>
> So is that *all* glass ? I can't find any reference anywhere to
> silicon being a component of bog-standard glass. Is it just naturally
> in there, and if so, in what form ? Or is it put in there for some
> reason, and for what purpose if so ?

Wiki is your friend.

http://en.wikipedia.org/wiki/Glass
http://en.wikipedia.org/wiki/Silicon
>
>
>
>>
>> Got NOTHING to do with the very nasty polluting and carcinogenic
>> processes involved in making silicon semiconductors.
>>
>>
>
> Yes, where the silicon has been extracted from whatever ore it occurs
> in, and then refined

from Wiki;
Silicon is commercially prepared by the reaction of high-purity silica with
wood, charcoal, and coal, in an electric arc furnace using carbon
electrodes. At temperatures over 1,900 �C (3,450 �F), the carbon reduces
the silica to silicon according to the following chemical equation:

(not semiconductor-grade Si,that uses trichlorosilane.)
>
>
>> .... Phil
>>
>
> Arfa
>
>

--
Jim Yanik
jyanik
at
localnet
dot com

== 5 of 5 ==
Date: Thurs, Sep 22 2011 9:21 am
From: Jim Yanik

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:3sveq.9442$BK4.3901@newsfe22.ams2:

>
>>
>> BTW: The discussion also involves LEDs. IMO, CFLs are an interim
>> step. They have far too many drawbacks to be a long term solution.
>> Incandescents are, of course, no solution at all.
>>
>>
>> --
>> Trevor Wilson
>> www.rageaudio.com.au
>>
>
> But actually, what exactly is the problem that we're trying to find a
> solution to ? I saw some figures a few weeks ago that said that if
> every single light bulb in the UK was changed to a CFL, the total
> saving in energy would amount to the output of one small power
> station. I suppose that you could argue that any saving is worth
> having, but I sometimes think that this religion of 'green' has
> completely overtaken common sense, and in some cases, the
> disadvantages of a substitute technology such as CFLs, needs to be
> weighed against the perceived disadvantages of what it's trying to
> replace. The problem with green technology is that its advocators are
> often zealots, who seek to portray the alternatives that they are
> pedaling as the only solution to a problem which often, only they see.
> They never tell the full story behind these technologies, being
> selective in the extreme. CFLs are a good example of this, where the
> *only* aspects that have been promoted, are the fact that they consume
> less energy for the same amount of light output as an 'equivalent'
> incandescent - and therein lies a can of worms before we start - and
> that they are supposedly longer lived. The huge amounts of
> manufacturing processes, and shipping energy for all the component
> parts, and all the other hidden energy inputs, are politely ignored.
> Not to mention the true disposal costs, if this is done properly. No
> one really understands the real manufacturing costs either, because
> governments are making sure that the true price is subsidised by
> collecting additional 'green' taxes via the energy companies, from the
> likes of you and I. If ever these subsidies are removed, CFLs will
> become a major expense to a household, unless they use really crappy
> quality Chinese imports that give poor light quality and poor starting
> characteristics, and are much shorter lived than people are currently
> being persuaded is the case.
>
> Arfa
>
>

the manufacture of CFLs produces much more pollution than making
incandescent lamps. it probably outweighs any savings from the use of CFLs
over I-lamps.
you don't need -any- mercury in making I-lamps,nor do you need phosphors.

--
Jim Yanik
jyanik
at
localnet
dot com

==============================================================================
TOPIC: Panasonic Home theater unit - mods?
http://groups.google.com/group/sci.electronics.repair/t/b645bcdb2854a867?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Sep 22 2011 7:41 am
From: "Dave, I can't do that"

Hi All,

I have a PanasonicSAHT670 that has worked well for quite a few years.
Recently the 5-DVD changer has begun jamming. I could get a
replacement for about 80-bucks but it is a major tear down as the
replacement does not come with the DVD accessing components. I have
begun to disassemble and it ain't going to be simple with hundreds of
parts.

So I thought I would just leave the changer out and use it as the
amplifier and add a DVD player (also Panasonic) I used with an amp,
before buying the Home Theater version.

Unfortunately the unit needs a sequence of signals from the changer as
all I get is "wait" on the display. The changer has several limit
switches which I have tried taping shut but it seems the unit may need
a sequence before moving on from the "Wait" as no combination of
switches lets it move on. It is not locked up as when I hit the "stand-
by" button it goes through the normal shut down process and says
"Goodbye."

Anyone have any suggestion how to make this work without the changer?

Thanks in advance.

I am also posting another question with an alternative. The Subject
for that is "Mix and match speaker impedance"

I am cross-posting to "sci.electronics.repair" (got yelled at here the
last time I duplicated a post at "repair" and didn't cross-post
instead) Hope I got it right this time.

Dave

==============================================================================
TOPIC: Mix and match speaker impedance
http://groups.google.com/group/sci.electronics.repair/t/6ffe1481a747ed23?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Sep 22 2011 8:00 am
From: "Dave, I can't do that"

Hi All,

I have a Panasonic SAHT670 that has worked well for quite a few years
and it kinda died. The details are in my other post here "Panasonic
Home theater unit - mods?"

I am wondering if I just buy a new stereo amplifier and use the
existing 5.1 speakers. I have
4 x 6-Ohm - 55-Watt for FR, FL, RR, RL
1 x 6-Ohm - 160-Watt Center
1 x 8-Ohm - 220-Watt Subwoofer.

So here's what I am thinking and ignoring any technical rights and
wrongs of mixing speaker impedance. {grin} I am not an audiophile and
never have the volume cranked up high.

The Stereo amp I am looking at has...
2 x 3-Ohm speaker outputs.
1 Subwoofer 1v-120K (I think it was) output.

What I would like to do is serial and parallel the 5 speakers. The FR,
RR and the FL, RL are easy, but the Center has two tweeters so it is
important for highs I am guessing, so I would like to incorporate that
too.

I can get a 100-Watt plate amp and attach that to the back of the
subwoofer box, so that's easy.

I do not want to buy a new home theater unit as when I installed this
one I made cut-outs in the walls for the speakers and all the units I
have recently looked at, the speakers are too big or the price is too
big for the near enough sized speakers.

I looked at 5.1 amps and/or receivers and they are out of my price
range right now.

So any suggestions here?

I am cross-posting to "sci.electronics.repair" (got yelled at here the
last time I duplicated a post at "repair" and didn't cross-post
instead) Hope I got it right this time.

Thanks

Dave

== 2 of 2 ==
Date: Thurs, Sep 22 2011 8:57 am
From: John Larkin

On Thu, 22 Sep 2011 08:00:10 -0700 (PDT), "Dave, I can't do that"
<davenpete@gmail.com> wrote:

>Hi All,
>
>I have a Panasonic SAHT670 that has worked well for quite a few years
>and it kinda died. The details are in my other post here "Panasonic
>Home theater unit - mods?"
>
>I am wondering if I just buy a new stereo amplifier and use the
>existing 5.1 speakers. I have
>4 x 6-Ohm - 55-Watt for FR, FL, RR, RL
>1 x 6-Ohm - 160-Watt Center
>1 x 8-Ohm - 220-Watt Subwoofer.
>
>So here's what I am thinking and ignoring any technical rights and
>wrongs of mixing speaker impedance. {grin} I am not an audiophile and
>never have the volume cranked up high.
>
>The Stereo amp I am looking at has...
>2 x 3-Ohm speaker outputs.
>1 Subwoofer 1v-120K (I think it was) output.
>
>What I would like to do is serial and parallel the 5 speakers. The FR,
>RR and the FL, RL are easy, but the Center has two tweeters so it is
>important for highs I am guessing, so I would like to incorporate that
>too.
>
>I can get a 100-Watt plate amp and attach that to the back of the
>subwoofer box, so that's easy.
>
>I do not want to buy a new home theater unit as when I installed this
>one I made cut-outs in the walls for the speakers and all the units I
>have recently looked at, the speakers are too big or the price is too
>big for the near enough sized speakers.
>
>I looked at 5.1 amps and/or receivers and they are out of my price
>range right now.
>
>So any suggestions here?
>
>I am cross-posting to "sci.electronics.repair" (got yelled at here the
>last time I duplicated a post at "repair" and didn't cross-post
>instead) Hope I got it right this time.
>
>Thanks
>
>Dave

Hook them up any old way. It's just audio. It doesn't matter.

John

==============================================================================
TOPIC: Why is there a thermistor in the power door lock circuit.
http://groups.google.com/group/sci.electronics.repair/t/c6bd6f6fca427310?hl=en
==============================================================================

== 1 of 3 ==
Date: Thurs, Sep 22 2011 8:02 am
From: micky

On Wed, 21 Sep 2011 20:17:01 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

>micky wrote:
>> On Tue, 20 Sep 2011 20:52:53 -0400, micky <NONONOmisc07@bigfoot.com>
>> wrote:
>>
>>
>>>What would the role of a thermistor be in the power door lock circuit
>>>of a car? It's in series with the door lock "motor", which might be
>>>a solenoid or maybe a rotating motor.
>>>
>>>Is it possible that it is meant to lower or turn off power to the
>>>mechanism if the circuit is left closed for some reason and the
>>>solenoid would otherwise overheat?
>>>
>>>The symbol it uses for a thermistor is a resistor symbol in an
>>>elongated circle, like a high school running track around the football
>>>field. Is that the usual symbol for a thermistor.
>>
>>
>> Well this says the symbol is retcangle with the stick figure of a
>> hockey stick across it.
>> http://www.best-microcontroller-projects.com/schematic-symbols.html
>> What's with Toyota anyhow? Are they wrong about the symbol, or maybe
>> they're wrong when they call it a thermistor!
>>
>Are you sure it isn't a circuit breaker?

Well, at the beginning of the the Toyota Electrical manaul, are two
pages with 36 electrical symbols and what they mean, and for this
circuit, the diagram uses a symbol which it says at the start of the
manual represents a thermistor, but it's not the symbol everyone else
uses.

Plus they use the same symbol** for the intake air temp sensor, the
engine coolant sensor, the Air Conditioning room temp sensor, and the
AC ambient temp sensor. . Might those really be thermistors too?

**a zigzag resistor symbol inside a circle that has been elongated in
one direction, like a model train track cricle with extra straight
track in opposite sides. .

I haven't taken apart the door yet, so I don't know what is actually
there.

My plan was to add to the passenger door-unlock output of the
door/burglar alarm Eloectronic Control Unit a wire to a relay, which
relay would unlock the trunk. What's connected to that output now is
the door lock/unlock motor (solenoid?) and this "thermistor", in
series, according to the diagram, and I wanted to understand what is
there now and what it does, before I start fiddling with the circuit.
The other end of the door lock circuit goes to ground and so will the
other end of my relay circuit.

I'm reticent because with the previous car and the previous alarm,
that I installed from scratch, everything was fine, except to open
the trunk, I had to hold down the third button for several seconds.
Because my turnk lid didn't move when unlatched, I thought it would
work better for me if I connected the trunk relay to the both-door
unlock output of the alarm I installed, in parallel with the
door-unlock relay. . However that appeared to screw everything up,
so that many of the alarm functions no longer worked. I must have put
too much drain on that output, even though I just doubled the drain
(two standard automotive relays instead of one) I shoulld I guess
have put the second relay in series with the first one, so that when
it powered the door-unlocks, it also powered the trunk relay.

I'm trying not to make the same sort of mistake here.

Thanks.

>Those are BI-metal
>and will open if they get too hot. They are also used in a
>time applications in cars.
>
>
>
>Jamie
>

== 2 of 3 ==
Date: Thurs, Sep 22 2011 8:08 am
From: micky

Thank you Franc and Dave.

Please see my reply to Jamie. There's another question towards the
end.

On Wed, 21 Sep 2011 13:56:10 -0700 (PDT), "Ron D."
<ron.dozier@gmail.com> wrote:

>Yep, the shop manuals for Toyotas are almost idiot's guides. They
>give specific tests, but no clue as to how the system operates. I

The manuals even start out by saying roughly, "There is not enough
information in these manuals for you to fix the car"

>think Toyota wants you to pay for a course to find that information
>out.

Maybe so, but I only own one car and I'm not paying!

> I've seen pieces of Toyota training publications and they are
>more generic, but do define how various systems function.

Hmmm. That would help.

>The Chevrolet guides I've used (2000) has a lot more design type info
>in their manual. A similar year Toyota is just different,
>
>PTC thermisters are regularly used for battery pack protection and
>solenoid protection. They are way more reliable for this application.

Okay, so all three of you say they are thermistors.

== 3 of 3 ==
Date: Thurs, Sep 22 2011 9:26 am
From: "Michael A. Terrell"

micky wrote:
>
> Well, at the beginning of the the Toyota Electrical manual, are two
> pages with 36 electrical symbols and what they mean, and for this
> circuit, the diagram uses a symbol which it says at the start of the
> manual represents a thermistor, but it's not the symbol everyone else
> uses.
>
> Plus they use the same symbol** for the intake air temp sensor, the
> engine coolant sensor, the Air Conditioning room temp sensor, and the
> AC ambient temp sensor. . Might those really be thermistors too?
>
> **a zigzag resistor symbol inside a circle that has been elongated in
> one direction, like a model train track cricle with extra straight
> track in opposite sides. .
>
> I haven't taken apart the door yet, so I don't know what is actually
> there.
>
> My plan was to add to the passenger door-unlock output of the
> door/burglar alarm Eloectronic Control Unit a wire to a relay, which
> relay would unlock the trunk. What's connected to that output now is
> the door lock/unlock motor (solenoid?) and this "thermistor", in
> series, according to the diagram, and I wanted to understand what is
> there now and what it does, before I start fiddling with the circuit.
> The other end of the door lock circuit goes to ground and so will the
> other end of my relay circuit.
>
> I'm reticent because with the previous car and the previous alarm,
> that I installed from scratch, everything was fine, except to open
> the trunk, I had to hold down the third button for several seconds.
> Because my turnk lid didn't move when unlatched, I thought it would
> work better for me if I connected the trunk relay to the both-door
> unlock output of the alarm I installed, in parallel with the
> door-unlock relay. . However that appeared to screw everything up,
> so that many of the alarm functions no longer worked. I must have put
> too much drain on that output, even though I just doubled the drain
> (two standard automotive relays instead of one) I shoulld I guess
> have put the second relay in series with the first one, so that when
> it powered the door-unlocks, it also powered the trunk relay.
>
> I'm trying not to make the same sort of mistake here.

A properly chosen thermistor will heat up and limit current if the
motor is stalled. It will also provide more a bit more current on cold
days, when you need more torque because of stiff grease in the
mechanism.

Car companies are not in the electronics business, so they use what
they feel that mechanics can understand.

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

==============================================================================
TOPIC: Need help with switching power supply repair
http://groups.google.com/group/sci.electronics.repair/t/efc81d21dede85df?hl=en
==============================================================================

== 1 of 7 ==
Date: Thurs, Sep 22 2011 8:25 am
From: "sci.electronics.repair"

On Sep 21, 8:08 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
> "senator richards" <rnewma...@gmail.com> wrote in message
>
> news:dd3e3ab9-1f98-41b8-a7ec-08431af9a33d@u20g2000yqj.googlegroups.com...
>
> > I am trying to troubleshoot a small SMPS that came from an A/V
> > switcher. Input is 120vac and it is supposed to output + and - 15vdc
> > at .8A. Currently it is outputting +17 on one output and somewhere
> > between +22 and +30 on the other output. My experience with SMPS has
> > usually been shorted rectifiers or bad output filter caps so the first
> > thing I did was check all the diodes and replace the output caps.
> > Obviously that didn't fix the problem. The high voltage is about
> > 170vdc. The supply to the pwm chip is fluctuating between 7-15v, so
> > i'm thinking this might be the problem, but maybe its something else.
> > In case its not obvious, i'm fairly new to tinkering with these
> > things. Thanks in advance for any help.
>
> > Randy
>
> The cap that filters the supply to the pwm chip on the primary side, maybe ?
> It's pretty common on most designs of switcher. Work on the thing on an
> isolation transformer if at all possible. They are potentially very very
> dangerous if you are not fully competent with them
>
> Arfa

Thanks for the help. I borrowed an ESR meter and checked the cap that
supplies the pwm chip. The cap is a 47uf 50v and esr measures .5 which
appears to be about right.

I don't have an isolation transformer but will look into getting one.

Thanks for your help.

-R

== 2 of 7 ==
Date: Thurs, Sep 22 2011 8:35 am
From: "sci.electronics.repair"

On Sep 21, 8:34 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
> senator richards wrote:
> > I am trying to troubleshoot a small SMPS that came from an A/V
> > switcher. Input is 120vac and it is supposed to output + and - 15vdc
> > at .8A. Currently it is outputting +17 on one output and somewhere
> > between +22 and +30 on the other output. My experience with SMPS has
> > usually been shorted rectifiers or bad output filter caps so the first
> > thing I did was check all the diodes and replace the output caps.
> > Obviously that didn't fix the problem. The high voltage is about
> > 170vdc. The supply to the pwm chip is fluctuating between 7-15v, so
> > i'm thinking this might be the problem, but maybe its something else.
> > In case its not obvious, i'm fairly new to tinkering with these
> > things. Thanks in advance for any help.
>
> > Randy
>
> See if you have an optical coupler in there. I've seen these used as
> part of the regulation and it's possible it isn't working any more.
>
> Also check for bad caps, ripple could be causing a reg issue.
>
> Jamie

There is an optical coupler. Its a CNX82A chip. Is there an easy way
to test it? I looked at Mouser and the part is discontinued and NLA.

I've checked all the caps for low ESR and they all check out OK.

Thanks.
-R

== 3 of 7 ==
Date: Thurs, Sep 22 2011 8:40 am
From: "sci.electronics.repair"

> Just to add to what Arfa said, the supply to the PWM chip often starts
> with a simple resistor feed from the +170V rectfied mains voltage, and
> is then augmented by a regenerated supply from a tap on the switchmode
> transformer. If this is the case, then there will be a small
> electrolytic filter capacitor (~10uF) that often develops high ESR.
>
> - Franc Zabkar

Hi Franc,

I found the 10uf cap you mention and measured the ESR. It was very
high (around 50), so i replaced it with another cap i had around. it
is not a low esr cap and only an 85 deg one, but figured it would be
ok for testing. it measures about 4.5 on the esr meter which is still
a little high (should be closer to 2). I still get the same result
when its hooked up.

-R

== 4 of 7 ==
Date: Thurs, Sep 22 2011 8:42 am
From: "sci.electronics.repair"

> try to check the main capacitor with an esr meter, or change it !
> build yourself easy an esr meter grab any you want on my web site below
> regards,

The main filter cap (68uf 400v) tests ok for ESR.

-R

== 5 of 7 ==
Date: Thurs, Sep 22 2011 8:41 am
From: "sci.electronics.repair"

On Sep 21, 11:41 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
> "senator richards"
>
> > Thanks in advance for any help.
>
> ** FFS - get yourself an ESR meter.
>
> .... Phil

I actually have one, but didn't have it with me the other day. I have
it now and have gone through all the caps. The only one that measured
bad was the 10uf 16v cap that Franc mentioned above. I changed it with
another cap and it didn't appear to fix the problem.

== 6 of 7 ==
Date: Thurs, Sep 22 2011 9:02 am
From: Jeff Liebermann

On Wed, 21 Sep 2011 13:31:46 -0700 (PDT), senator richards
<rnewman36@gmail.com> wrote:

>I am trying to troubleshoot a small SMPS that came from an A/V
>switcher.

A photo of the PS would be helpful. Mostly, I'm looking for what
manner of regulator chip is being used and whether there's a
transformer or optoisolator involved.

>Input is 120vac and it is supposed to output + and - 15vdc
>at .8A. Currently it is outputting +17 on one output and somewhere
>between +22 and +30 on the other output.

If you have +30VDC on an output circuit that is suppose to only
tolerate +15VDC, it's possible that the output caps are now dead,
especially if this PS has been run for quite some time. The output
caps are probably rated at 25WV, which doesn't apprecitate the 30V (or
more if there are voltage spikes on the output).

>My experience with SMPS has
>usually been shorted rectifiers or bad output filter caps

Yeah, that's the usual problem.

>so the first
>thing I did was check all the diodes and replace the output caps.
>Obviously that didn't fix the problem. The high voltage is about
>170vdc. The supply to the pwm chip is fluctuating between 7-15v,

Fluctuations like that are sometimes arcing in the xformer or spurious
oscillations in the regulator chip. High output voltage usually means
a failure in whatever is regulating or sensing the output voltage. As
others have suggested, get an isolation xformer before you kill
yourself. Then, attach a scope probe to the output lines, regulator
pins, and optoisolator, and see what's causing the fluctuations.
That's not normal.

--
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

== 7 of 7 ==
Date: Thurs, Sep 22 2011 9:30 am
From: Jim Yanik

Jeff Liebermann <jeffl@cruzio.com> wrote in
news:p8mm77dur3hb6af5n9i275438jkbrqo2sj@4ax.com:

> On Wed, 21 Sep 2011 13:31:46 -0700 (PDT), senator richards
><rnewman36@gmail.com> wrote:
>
>>I am trying to troubleshoot a small SMPS that came from an A/V
>>switcher.
>
> A photo of the PS would be helpful. Mostly, I'm looking for what
> manner of regulator chip is being used and whether there's a
> transformer or optoisolator involved.
>
>>Input is 120vac and it is supposed to output + and - 15vdc
>>at .8A. Currently it is outputting +17 on one output and somewhere
>>between +22 and +30 on the other output.
>
> If you have +30VDC on an output circuit that is suppose to only
> tolerate +15VDC, it's possible that the output caps are now dead,
> especially if this PS has been run for quite some time. The output
> caps are probably rated at 25WV, which doesn't apprecitate the 30V (or
> more if there are voltage spikes on the output).
>
>>My experience with SMPS has
>>usually been shorted rectifiers or bad output filter caps
>
> Yeah, that's the usual problem.
>
>>so the first
>>thing I did was check all the diodes and replace the output caps.
>>Obviously that didn't fix the problem. The high voltage is about
>>170vdc. The supply to the pwm chip is fluctuating between 7-15v,
>
> Fluctuations like that are sometimes arcing in the xformer or spurious
> oscillations in the regulator chip. High output voltage usually means
> a failure in whatever is regulating or sensing the output voltage. As
> others have suggested, get an isolation xformer before you kill
> yourself. Then, attach a scope probe to the output lines, regulator
> pins, and optoisolator, and see what's causing the fluctuations.
> That's not normal.
>

determine what output rail the supply regulates from.
then check it's filter caps for ESR.

I've seen where the filter cap(s) on that rail had a high ESR,and the PWM
control tried to drive it back to the nominal voltage,and the OTHER output
rails climbed high because of that. And that caused high dissipation in
other circuits that eventually burned a hole in the PCB.

you could also have a bad electrolytic on the reference output on the PWM
chip. or a reference divider resistor changed value.

Find the datasheet for the PWM Ic and learn the inputs and what levels they
should be at,that will tell you how your supply is supposed to work.

--
Jim Yanik
jyanik
at
localnet
dot com

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