sci.electronics.repair - 25 new messages in 5 topics - digest

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

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Today's topics:

* Technics SA-310 Intermittent Weak Left Channel - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/24c0d76fe3922429?hl=en
* Best solder free electrical connection - 18 messages, 17 authors
http://groups.google.com/group/sci.electronics.repair/t/11e5e6461418f740?hl=en
* Beyond AWG - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/6108ec0943f8d321?hl=en
* viewsonic VX800 LCD - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/53f899d96e08c6da?hl=en
* TV Power Cord - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/58b460c2437269b4?hl=en

==============================================================================
TOPIC: Technics SA-310 Intermittent Weak Left Channel
http://groups.google.com/group/sci.electronics.repair/t/24c0d76fe3922429?hl=en
==============================================================================

== 1 of 3 ==
Date: Mon, Aug 16 2010 10:29 am
From: Meat Plow

On Mon, 16 Aug 2010 11:56:51 -0500, William R. Walsh wrote:

> Hi!
>
>> None I can think of other than using an alternative audio source like
>> an FM tuner or tape playback to generate signal and monitor the rail
>> voltages with an analog meter or digital with a logarithmic display. If
>> it falls more than say 10% at full volume you may have an issue with
>> the rail supply. That's about it, can't help more if you don't have a
>> minimal amount of test gear like an audio generator and volt meter.
>
> I do have an analog multimeter (if I can find it!) that would probably
> do. What I don't have is any sort of an audio signal generator. It did
> occur to me that I have some various audio frequency sweeps and the like
> stored on my computer, but I don't know if there are any fixed frequency
> samples in there.
>
> My intention is to perform some checks on the power supply. I did notice
> what looked like dimming or blanking from the tuning display during loud
> passages in the music. It was so brief that I could not be sure.
>
> William

Basically you want to put a load on the power supply. Any way you can get
the volume up so you can observe the drop, if any, in voltage on the rail
could help you. Personally I haven't seen a lot of standard pass-filtered
supplies dip in voltage drastically enough to weaken the output of the
channel significantly and intermittently as in your case. I'd be looking
for a lose connection first.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 2 of 3 ==
Date: Mon, Aug 16 2010 11:48 am
From: "William R. Walsh"

Hi!

> Personally I haven't seen a lot of standard pass-filtered
> supplies dip in voltage drastically enough to weaken the output of the
> channel significantly and intermittently as in your case. I'd be looking
> for a lose connection first.

Eventually the left channel "stuck" in its broken state. Now it's distorted
no matter the volume or source. I've also noticed a "thump" sound from the
left speaker at startup where there was none before. (The right channel
continues to function normally.) Knowing these receivers' tendency to put a
power supply rail on a speaker without warning, I've taken the good speakers
away and put crappy ones in their place.

About an hour ago, I powered the unit up and played the drums on it to see
if anything was obviously loose. That failed to produce a result, so I took
Arfa's advice and examined the soldering on the STK 2038 II module. I found
only two joints that looked suspect, so I redid them and found no
improvement in the units' behavior. I looked all over the main board and
didn't find any other problems.

I suspect the power supply--especially the filter caps--mainly because this
unit runs *very* hot and always has. It'll get hot enough that you don't
want to keep your hand on the top of the cover. The filter capacitors sit in
the worst of this heat, right between the power transformer and power
amplifier module. What kind of shape could those and other capacitors in the
vicinity be after 27 years? They're 85 degree C units, so I wonder...and
replacements are cheap enough...

William

== 3 of 3 ==
Date: Mon, Aug 16 2010 2:20 pm
From: Meat Plow

On Mon, 16 Aug 2010 13:48:44 -0500, William R. Walsh wrote:

> Hi!
>
>> Personally I haven't seen a lot of standard pass-filtered supplies dip
>> in voltage drastically enough to weaken the output of the channel
>> significantly and intermittently as in your case. I'd be looking for a
>> lose connection first.
>
> Eventually the left channel "stuck" in its broken state. Now it's
> distorted no matter the volume or source. I've also noticed a "thump"
> sound from the left speaker at startup where there was none before. (The
> right channel continues to function normally.) Knowing these receivers'
> tendency to put a power supply rail on a speaker without warning, I've
> taken the good speakers away and put crappy ones in their place.
>
> About an hour ago, I powered the unit up and played the drums on it to
> see if anything was obviously loose. That failed to produce a result, so
> I took Arfa's advice and examined the soldering on the STK 2038 II
> module. I found only two joints that looked suspect, so I redid them and
> found no improvement in the units' behavior. I looked all over the main
> board and didn't find any other problems.
>
> I suspect the power supply--especially the filter caps--mainly because
> this unit runs *very* hot and always has. It'll get hot enough that you
> don't want to keep your hand on the top of the cover. The filter
> capacitors sit in the worst of this heat, right between the power
> transformer and power amplifier module. What kind of shape could those
> and other capacitors in the vicinity be after 27 years? They're 85
> degree C units, so I wonder...and replacements are cheap enough...
>
> William

You could always swap the caps since each channel has its own pair. Or
just shotgun them all and cross your fingers.

--
Live Fast, Die Young and Leave a Pretty Corpse

==============================================================================
TOPIC: Best solder free electrical connection
http://groups.google.com/group/sci.electronics.repair/t/11e5e6461418f740?hl=en
==============================================================================

== 1 of 18 ==
Date: Mon, Aug 16 2010 10:43 am
From: "john hamilton"

I have to connect this AAA battery holder to a toy. Although I have a small
soldering iron, my soldering skills are poor. I can see myself easily
melting all the plastic around the contacts before I can get anything to
stick to the tabs. (The part of the tabs with the small hole will bend
upwards giving some clearence).

http://tinypic.com/r/iqx3pf/4

My immediate plan is to poke a few strands of wire through the holes in the
connection tabs twist and then apply some nail varnish to stop it unwinding.
Since its a toy it does not need to be totally foolproof.

If anyone had any ideas that were a bit more sophisticated I would be
gratefull. Thanks.

== 2 of 18 ==
Date: Mon, Aug 16 2010 10:54 am
From: "Ralph Mowery"

"john hamilton" <bluestar95@mail.invalid> wrote in message
news:i4btbg$m7c$1@news.eternal-september.org...
>I have to connect this AAA battery holder to a toy. Although I have a small
>soldering iron, my soldering skills are poor. I can see myself easily
>melting all the plastic around the contacts before I can get anything to
>stick to the tabs. (The part of the tabs with the small hole will bend
>upwards giving some clearence).
>
> http://tinypic.com/r/iqx3pf/4
>
> My immediate plan is to poke a few strands of wire through the holes in
> the connection tabs twist and then apply some nail varnish to stop it
> unwinding. Since its a toy it does not need to be totally foolproof.
>
> If anyone had any ideas that were a bit more sophisticated I would be
> gratefull. Thanks.
>

While you don't want to hear it, solder it. Just use some fine 60/40 rosen
core solder. The main thing with soldering is to get the connection clean.
If bare copper wire, scrape or sand it so it shines.

I would not use the nail varnish. Copper wire should hold its shape without
the varnish. Also the varnish could get between the wire and tabs. You
might want to get some electrical tape and wrap it longways around the
battery box to help hold the wire in contact with the tabs.

== 3 of 18 ==
Date: Mon, Aug 16 2010 11:05 am
From: "Toby"

"john hamilton" <bluestar95@mail.invalid> wrote in message
news:i4btbg$m7c$1@news.eternal-september.org...
> I have to connect this AAA battery holder to a toy. Although I have a
> small soldering iron, my soldering skills are poor. I can see myself
> easily melting all the plastic around the contacts before I can get
> anything to stick to the tabs. (The part of the tabs with the small hole
> will bend upwards giving some clearence).
>
> http://tinypic.com/r/iqx3pf/4
>
> My immediate plan is to poke a few strands of wire through the holes in
> the connection tabs twist and then apply some nail varnish to stop it
> unwinding. Since its a toy it does not need to be totally foolproof.
>
> If anyone had any ideas that were a bit more sophisticated I would be
> gratefull. Thanks.
>

Solder is the only reliable way, IMO

Just bend the tabs out, so they are not touching the plastic, make sure the
iron is nice and hot, dab some solder on the end of the iron, then place
this on one of the tabs and feed in a little more solder to tin the tab,
should take a couple of seconds.
Now strip about 5mm of the wires and tin the end of the wire, if the
insulation shrinks back, then snip the end of the wire off so it is about
5mm.
Place the wire on top of the solder on the tab and heat the wire until the
solder on the tab melts again.

Hold the wire with something other than your hand, as it may get quite hot!

Once it has cooled, marvel at your handywork :-)

Or, buy these two from eBay, or anywhere that sells this sort of stuff...
350373699059 (Twin AA battery holder with a PP£ type connector on the top)
and one of these
350350685890 (PP3 battery connector)

Toby...

== 4 of 18 ==
Date: Mon, Aug 16 2010 11:08 am
From: "William Sommerwerck"

55 years ago, I was afraid of soldering, afraid I wouldn't be able to do it
well. I was wrong. It's not that difficult; it just takes a bit of practice.

If you're really uncomfortable, ask a friend to do it for you.

Unsoldered connections might work for a while, but will eventually fail.

== 5 of 18 ==
Date: Mon, Aug 16 2010 11:17 am
From: Rich Webb

On Mon, 16 Aug 2010 18:43:08 +0100, "john hamilton"
<bluestar95@mail.invalid> wrote:

>I have to connect this AAA battery holder to a toy. Although I have a small
>soldering iron, my soldering skills are poor. I can see myself easily
>melting all the plastic around the contacts before I can get anything to
>stick to the tabs. (The part of the tabs with the small hole will bend
>upwards giving some clearence).
>
>http://tinypic.com/r/iqx3pf/4
>
>My immediate plan is to poke a few strands of wire through the holes in the
>connection tabs twist and then apply some nail varnish to stop it unwinding.
>Since its a toy it does not need to be totally foolproof.
>
>If anyone had any ideas that were a bit more sophisticated I would be
>gratefull. Thanks.

What Ralph said. Also, if you can get some, apply a dab of rosin flux
paste to the joint before you heat it. That helps the solder to "wet"
the surfaces and flow into the joint better.

And ensure that you have something keeping the battery holder and the
wire in place. I'd go so far as to put batteries in the thing so that it
could be clamped into a soft-jawed vice and use one of those "third
hand" thingies to hold the wire securely. Trying to keep the battery
holder in place with your palm, the wire under your elbow, with the
soldering iron in one hand and the solder in the other isn't likely to
result in a satisfactory soldering job. Not that *I've* ever done that,
of course <cough cough>

--
Rich Webb Norfolk, VA

== 6 of 18 ==
Date: Mon, Aug 16 2010 11:31 am
From: Owain

On Aug 16, 7:17 pm, Rich Webb wrote:
> And ensure that you have something keeping the battery holder and the
> wire in place. I'd go so far as to put batteries in the thing so that it
> could be clamped into a soft-jawed vice and use one of those "third
> hand" thingies to hold the wire securely. Trying to keep the battery
> holder in place with your palm, the wire under your elbow, with the
> soldering iron in one hand and the solder in the other isn't likely to
> result in a satisfactory soldering job. Not that *I've* ever done that,
> of course <cough cough>

I've used one hand for the Thing, one hand for the iron, and held the
solder in my mouth before now ...

Fumes can get a bit eye-stingy though.

Big wodges of blu-tack can also be handy.

Owain

== 7 of 18 ==
Date: Mon, Aug 16 2010 11:35 am
From: andrew@cucumber.demon.co.uk (Andrew Gabriel)

In article <i4btbg$m7c$1@news.eternal-september.org>,
"john hamilton" <bluestar95@mail.invalid> writes:
> I have to connect this AAA battery holder to a toy. Although I have a small
> soldering iron, my soldering skills are poor. I can see myself easily
> melting all the plastic around the contacts before I can get anything to
> stick to the tabs. (The part of the tabs with the small hole will bend
> upwards giving some clearence).
>
> http://tinypic.com/r/iqx3pf/4
>
> My immediate plan is to poke a few strands of wire through the holes in the
> connection tabs twist and then apply some nail varnish to stop it unwinding.
> Since its a toy it does not need to be totally foolproof.
>
> If anyone had any ideas that were a bit more sophisticated I would be
> gratefull. Thanks.

If you say which town/country you live in, someone here might
volunteer to solder it for you. If you have an electronics repair
shop near which does the work on the premises, they would probably
do it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

== 8 of 18 ==
Date: Mon, Aug 16 2010 11:37 am
From: jeff_wisnia

john hamilton wrote:
> I have to connect this AAA battery holder to a toy. Although I have a small
> soldering iron, my soldering skills are poor. I can see myself easily
> melting all the plastic around the contacts before I can get anything to
> stick to the tabs. (The part of the tabs with the small hole will bend
> upwards giving some clearence).
>
> http://tinypic.com/r/iqx3pf/4
>
> My immediate plan is to poke a few strands of wire through the holes in the
> connection tabs twist and then apply some nail varnish to stop it unwinding.
> Since its a toy it does not need to be totally foolproof.
>
> If anyone had any ideas that were a bit more sophisticated I would be
> gratefull. Thanks.
>
>

While I agree with previous posters that soldering shouldn't be a big
problem, if you really don't want to try it yourself you should be able
to find someone else who will.

Or, go for your "twist through the holes" approach and use a drop of
electrically conductive epoxy on the joint:

http://www.pemro.com/itemdesc.asp?ic=LOC-1119

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.

== 9 of 18 ==
Date: Mon, Aug 16 2010 11:45 am
From: The Natural Philosopher

jeff_wisnia wrote:
> john hamilton wrote:
>> I have to connect this AAA battery holder to a toy. Although I have a
>> small soldering iron, my soldering skills are poor. I can see myself
>> easily melting all the plastic around the contacts before I can get
>> anything to stick to the tabs. (The part of the tabs with the small
>> hole will bend upwards giving some clearence).
>>
>> http://tinypic.com/r/iqx3pf/4
>>
>> My immediate plan is to poke a few strands of wire through the holes
>> in the connection tabs twist and then apply some nail varnish to stop
>> it unwinding. Since its a toy it does not need to be totally foolproof.
>>
>> If anyone had any ideas that were a bit more sophisticated I would be
>> gratefull. Thanks.
>>
>
>
> While I agree with previous posters that soldering shouldn't be a big
> problem, if you really don't want to try it yourself you should be able
> to find someone else who will.
>
> Or, go for your "twist through the holes" approach and use a drop of
> electrically conductive epoxy on the joint:
>
> http://www.pemro.com/itemdesc.asp?ic=LOC-1119
>

..which will at best approximate to a 1k ohm resistor.:-)

> Jeff
>

== 10 of 18 ==
Date: Mon, Aug 16 2010 11:56 am
From: "hr(bob) hofmann@att.net"

On Aug 16, 12:43 pm, "john hamilton" <bluesta...@mail.invalid> wrote:
> I have to connect this AAA battery holder to a toy. Although I have a small
> soldering iron, my soldering skills are poor. I can see myself easily
> melting all the plastic around the contacts before I can get anything to
> stick to the tabs. (The part of the tabs with the small hole will bend
> upwards giving some clearence).
>
> http://tinypic.com/r/iqx3pf/4
>
> My immediate plan is to poke a few strands of wire through the holes in the
> connection tabs twist and then apply some nail varnish to stop it unwinding.
> Since its a toy it does not need to be totally foolproof.
>
> If anyone had any ideas that were a bit more sophisticated I would be
> gratefull. Thanks.

Surely you know someone who knows how to solder. You need clean bare
metal, some solder and some flux, and a hot iron. Practice a little
bit on a strip of metal the same size as the tab, that you cut from a
tin can.

== 11 of 18 ==
Date: Mon, Aug 16 2010 12:05 pm
From: Djornsk

On 16/08/2010 18:43, john hamilton wrote:
> I have to connect this AAA battery holder to a toy. Although I have a small
> soldering iron, my soldering skills are poor. I can see myself easily
> melting all the plastic around the contacts before I can get anything to
> stick to the tabs. (The part of the tabs with the small hole will bend
> upwards giving some clearence).
>
> http://tinypic.com/r/iqx3pf/4
>
> My immediate plan is to poke a few strands of wire through the holes in the
> connection tabs twist and then apply some nail varnish to stop it unwinding.
> Since its a toy it does not need to be totally foolproof.
>
> If anyone had any ideas that were a bit more sophisticated I would be
> gratefull. Thanks.
>
>

Depending on the dimensions of the tab it may be possible to bend it
around the wire and carefully crimp it with sidecutters. Next try to
anchor the wire to the battery holder a short distance along the wire
from the tab to prevent it fracturing due to movement or vibration.
You could then use your varnish (or a glue gun) to coat the connection
to offer some protection from oxidation.
This is not as good as a soldered joint done properly, but would
probably be better than a soldered joint done badly.

== 12 of 18 ==
Date: Mon, Aug 16 2010 12:25 pm
From: "tm"

Why don't you try to learn to solder? Get some copper wire and practice
making connections. Ten or so should get you going. Not only will you
achieve
your task but you will have picked up a new skill as a plus. The trick is to
place the hot iron against the joint and heat it until it will melt the
solder. Just
hold the solder on the joint until that point. To see if the iron is hot
enough, just
melt some solder on the tip. This is known as tinning the tip. Clean the tip
by
wiping it on a damp sponge.

You will only need a 15 to 25 watt iron to do this and some rosin core
tin/lead
solder. Radio shack comes to mind for both.

Have fun.

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

== 13 of 18 ==
Date: Mon, Aug 16 2010 12:39 pm
From: Bob Eager

On Mon, 16 Aug 2010 18:43:08 +0100, john hamilton wrote:

> I have to connect this AAA battery holder to a toy. Although I have a
> small soldering iron, my soldering skills are poor. I can see myself
> easily melting all the plastic around the contacts before I can get
> anything to stick to the tabs.

To add to the other suggestions about soldering: if you can get/borrow a
temperature controlled iron, run it at a lower temperature and use 63/37
solder.

--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

== 14 of 18 ==
Date: Mon, Aug 16 2010 12:45 pm
From: Fred McKenzie

In article <i4btbg$m7c$1@news.eternal-september.org>,
"john hamilton" <bluestar95@mail.invalid> wrote:

> Although I have a small
> soldering iron, my soldering skills are poor.

John-

Soldering appears to me to be the best solution. Invite a friend to do
the soldering. Bend the tab up first, and solder quickly to minimize
melting the plastic underneath. The plastic should become firm again
after it cools.

What about threading tiny self-tapping screws into the holes in the
rivets that connect the lugs to the contacts?

Fred

== 15 of 18 ==
Date: Mon, Aug 16 2010 1:15 pm
From: tony sayer

In article <i4c0iu$8he$1@news.eternal-september.org>, jeff_wisnia
<jwisniaDumpThisPart@conversent.net> scribeth thus
>john hamilton wrote:
>> I have to connect this AAA battery holder to a toy. Although I have a small
>> soldering iron, my soldering skills are poor. I can see myself easily
>> melting all the plastic around the contacts before I can get anything to
>> stick to the tabs. (The part of the tabs with the small hole will bend
>> upwards giving some clearence).
>>
>> http://tinypic.com/r/iqx3pf/4
>>
>> My immediate plan is to poke a few strands of wire through the holes in the
>> connection tabs twist and then apply some nail varnish to stop it unwinding.
>> Since its a toy it does not need to be totally foolproof.
>>
>> If anyone had any ideas that were a bit more sophisticated I would be
>> gratefull. Thanks.
>>
>>
>
>
>While I agree with previous posters that soldering shouldn't be a big
>problem, if you really don't want to try it yourself you should be able
>to find someone else who will.
>

Better still have a practice on some bits of wire etc before you do this
joint and than you've learnt a new skill:))..

Do get the joint hot, and keep it hot just long enough to make it all
flow properly it seems to me that under powered irons are the biggest
cause of poor soldering...

--
Tony Sayer

== 16 of 18 ==
Date: Mon, Aug 16 2010 1:27 pm
From: robgraham

On 16 Aug, 20:39, Bob Eager <rd...@spamcop.net> wrote:
> On Mon, 16 Aug 2010 18:43:08 +0100, john hamilton wrote:
> > I have to connect this AAA battery holder to a toy. Although I have a
> > small soldering iron, my soldering skills are poor. I can see myself
> > easily melting all the plastic around the contacts before I can get
> > anything to stick to the tabs.
>
> To add to the other suggestions about soldering: if you can get/borrow a
> temperature controlled iron, run it at a lower temperature and use 63/37
> solder.
>
> --
> Use the BIG mirror service in the UK:
> http://www.mirrorservice.org
>
> *lightning protection* - a w_tom conductor

I notice that nobody has raised the point for the OP that his problem
of previous soldering is that he is possibly using too powerful a
soldering iron - one with too big a bit. This is the most likely
cause of his problem with melting the support for the tag he is
soldering to. Haven't we all done it - and even with a temperature
controlled one and 50 years of experience I softened the mount for the
centre pin of a connector yesterday, and had to go back and apply heat
to straighten it.

John - I've had a quick scan through Ebay and suggest that
#370414838261 is a good buy (ie I've got one!) for a controlled iron
if you feel that the advise to try,try,try again is worth following.

Rob

== 17 of 18 ==
Date: Mon, Aug 16 2010 1:48 pm
From: "steve robinson"

robgraham wrote:

> On 16 Aug, 20:39, Bob Eager <rd...@spamcop.net> wrote:
> > On Mon, 16 Aug 2010 18:43:08 +0100, john hamilton wrote:
> > > I have to connect this AAA battery holder to a toy. Although I
> > > have a small soldering iron, my soldering skills are poor. I
> > > can see myself easily melting all the plastic around the
> > > contacts before I can get anything to stick to the tabs.
> >
> > To add to the other suggestions about soldering: if you can
> > get/borrow a temperature controlled iron, run it at a lower
> > temperature and use 63/37 solder.
> >
> > --
> > Use the BIG mirror service in the UK:
> > http://www.mirrorservice.org
> >
> > *lightning protection* - a w_tom conductor
>
> I notice that nobody has raised the point for the OP that his
> problem of previous soldering is that he is possibly using too
> powerful a soldering iron - one with too big a bit. This is the
> most likely cause of his problem with melting the support for the
> tag he is soldering to. Haven't we all done it - and even with a
> temperature controlled one and 50 years of experience I softened
> the mount for the centre pin of a connector yesterday, and had to
> go back and apply heat to straighten it.
>
> John - I've had a quick scan through Ebay and suggest that
> #370414838261 is a good buy (ie I've got one!) for a controlled iron
> if you feel that the advise to try,try,try again is worth following.
>
> Rob

Try lead based solder 60/40 has a lower melting point

== 18 of 18 ==
Date: Mon, Aug 16 2010 2:20 pm
From: "hr(bob) hofmann@att.net"

Is the OP in the USA or the UK or where?????

==============================================================================
TOPIC: Beyond AWG
http://groups.google.com/group/sci.electronics.repair/t/6108ec0943f8d321?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Aug 16 2010 11:07 am
From: Jeff Liebermann

On Mon, 16 Aug 2010 10:19:26 -0700, "Paul Hovnanian P.E."
<paul@hovnanian.com> wrote:

>The biggest problem is going to be counting 1800 turns! I can make a jig to
>wind this on my bench lathe and incorporate a magnet/Hall sensor to advance
>a counter.

Magnetic is rotation speed sensitive. If you go too slow, it won't
register a pulse. I suggest optical with an LED emitter/detector
pair. Debounce the output with a one-shot. Send the output pulses to
an HP universal counter. Count pulses. Good luck.

You might also make some kind of friction clutch arrangement intended
to keep the tension under the breaking strength of the #45 AWG wire.
This way, the lathe can spin merrily while you control the wire feed
with your fingers. (Hint: wear gloves). If rigidly attach the spool
to the lathe, it's gonna break.

When I moved to my house in the woods 35 years ago, I bought a chain
saw. I then dropped and split about 1 cord of firewood. The next
year, I hired someone to deliver firewood, and have lived happily ever
after. I also disposed of my dead cars several years ago as I needed
the parking spaces.

--
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 2 ==
Date: Mon, Aug 16 2010 2:13 pm
From: "Paul Hovnanian P.E."

Jeff Liebermann wrote:
>
[snip]

> I also disposed of my dead cars several years ago as I needed
> the parking spaces.

I do too whenever I find them. Which reminds me: Time to mow the lawn
again.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Experience is the worst teacher. It always gives the test
first and the instruction afterward.

==============================================================================
TOPIC: viewsonic VX800 LCD
http://groups.google.com/group/sci.electronics.repair/t/53f899d96e08c6da?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Aug 16 2010 12:08 pm
From: divx dude

On Aug 15, 4:55 pm, PlainBil...@yawho.com wrote:
> On Sat, 14 Aug 2010 10:57:07 -0700 (PDT), divx dude
>
>
>
> <divx.d...@gmail.com> wrote:
> >i got these two monitors VX800 nice looking 18" LCD desktop monitors
> >that use an external power brick.
> >my research sez the brick is 12vdc at 5A.
> >my plan was to makeshift something, i found a 3mm?
> >plug to fit the power jack and wired it to the 12v drive molex line on
> >an old AT power supply form the 486 days pre-ATX.
> >the 12v rail is rated at 8A.
> >the grren light on the moniotor comes on but flashes display text the
> >POST screen on the PC flashes it only for a second.
>
> >i can repeat that 1 second by cycling the power button but thats all i
> >can get from it. i tried a 12v rated lass than 2A
> >same responce. i tried the drive molex line from the ATX supply on the
> >PC i'm using tot test it but no green light. i measured the volts on
> >that line and its like 13.5vdc or so..
> >there was another brick i tried also but no green light and slightly
> >more than 13vdc.
> >so the monitor is picky and refuses 13v+
>
> >i havent tried the other monitor yet. im expecting someone already
> >knows these are buggy and bet it probably has the same issue.
>
> >requesting any assistance u smart people can provide.
>
> Other than the substitute power supply, this is the classic 'two
> seconds to black' scenario. A backlight inverter is essentially a
> constant-current AC source with protection features to detect an open
> lamp or excessive current. The protection is disabled for about two
> seconds when the backlights are activated to allow the system to reach
> a steady state. Thus, a persistant fault results in 'two seconds to
> black.
>
> Possible faults include bad electrolytic caps on the inverter, one or
> more bad CCFLs, a bad solder joint on the CCFLs, a bad inverter
> transformer, a shorted transistor, or the real fun possibility, a
> defective component in the protection circuitry. In theory, slightly
> high or low voltage should not cause the problem, but it shouldn't be
> ignored.
>
> The first step is to open the monitors up and look for obvious
> problems, especially bulging caps. Then you try arranging the
> monitors in such a manner that you can hook one or more of the CCFLs
> from monitor A to the inverter in monitor B. If one of the CCFLs in
> monitor A will result in monitor B working normally you have
> identified a problem.
>
> PlainBill

thanks for the input guys.
i decided to return the monitors to the guy that sold them.
amazing how "losing" the power supplies can entice a moron
like me into thinking hes getting an easy deal..
not worth the effort.

i do appreciate the tips tho...im sure i will
need to fix one sooner or later..

==============================================================================
TOPIC: TV Power Cord
http://groups.google.com/group/sci.electronics.repair/t/58b460c2437269b4?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Aug 16 2010 1:58 pm
From: Cydrome Leader

NF <franklin4321@cox.net> wrote:
> Hi,
>
> I just had a shop replace the power cord on a Sony KV-27FS100L tube TV. (An
> in home service call.) The guy who did the repair said that the connector on
> the replacement cord which connects to the board is not an exact fit, but is
> the closest they had and will work. (And yes, the TV does work). But because
> the connector is not as tight fitting as the original, the repair guy said
> it is very important to have very good strain relief to avoid tension on the
> cord. (I was not home when it was repaired, this is what I was told by the
> person who was home.) However, when I got home, I found that the repair guy
> did not put a strain relief device in the hole where the cord is supposed to
> exit the TV. Instead, he deliberately wedged the cord between where the
> bottom and back parts of the case meet. This was his idea for strain relief.
> (The original hole where the cord used to exit is now just an empty hole.)
>
> Problem is, the wedged cord causes the case not to fit together properly.
> The bottom is now uneven, so the TV sits a little bit crooked. If you lift
> up the back of the TV, you can see the bottom bulging out on one side,
> looking like it's going to break the plastic tab. My other concern is that
> the cord is wedged between a protrusion of the bottom and the back case, so
> the 100lbs of weight from this TV is now pinching this cord. So my questions
> are:
>
> Is this safe? Can this pinch the cord enough to damage the internal
> conductors or cord insulation? This TV literally weighs 100 pounds.

it's not safe. It's a shitty repair job as well.

> Is this really a stronger strain relief than just obtaining a strain relief
> device for the hole the cord is supposed to exit through?

> The shop was contacted, and asked if the proper replacement cord could be
> obtained, even if we have to pay extra for the cord itself. (As long as we
> are not charged for another service call or more labor.) The shop called
> back after a day and said the exact replacement cord is no longer available,
> and they don't have access to any. They said they'd get back to us later,
> they haven't yet.
>
> If the cord isn't available, should they at least be able to get a strain
> relief device to fit the hole so the cord isn't wedged in between the case
> parts? And would such a strain relief be strong enough even though the
> connector on the board doesn't fit as tight as the original?

There's lots of ways this repair could be done, without the original cord
set and without pinching the cord in the cabinet.

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