Problems diagnosing TV
 

Kind folks,

I'm having a hard time trying to guess what's going wrong with our TV,
though, to be honest, I haven't yet cracked the sucker open because I'm
only home when the baby in the same room is trying to get to sleep. The
TV is a 20-incher less than 15 years old, bought recently used.

Problems:
-- Picture moves vertically, sometimes drifting, sometimes jumping,
generally moving downward

-- Hugging the sides of the TV at the back seem to fix that problem

-- Screen will turn to static and take sound with it; turning it off and
then on again fixes it temporarily. It's almost sudden onset -- maybe a
second or two of fuzziness, then a washout.

-- Warning sign of vertical movement seems to be increasing
fuzziness/static in display, though nothing too seriously. Black is no
longer quite so black.

-- The complete fuzzout seems to be driven by something else, like it
has to be on for an hour and then it's constant.

I thought this was a problem with the vertical hold circuitry, but the
fuzzout with sound is completely throwing me for a loop. That makes me
wonder if there's a heat/dust problem going on.

Any advice would be greatly appreciated. I'm of the mind to try a
vacuum, canned air and some electric parts cleaner, but I'd love some
direction before I electrocute myself. =)


Mike

Problems diagnosing TV
 

"Mike Stucka" wrote in message
...
Kind folks,

I'm having a hard time trying to guess what's going wrong with our TV,
though, to be honest, I haven't yet cracked the sucker open because I'm
only home when the baby in the same room is trying to get to sleep. The TV
is a 20-incher less than 15 years old, bought recently used.

Problems:
-- Picture moves vertically, sometimes drifting, sometimes jumping,
generally moving downward

-- Hugging the sides of the TV at the back seem to fix that problem

-- Screen will turn to static and take sound with it; turning it off and
then on again fixes it temporarily. It's almost sudden onset -- maybe a
second or two of fuzziness, then a washout.

-- Warning sign of vertical movement seems to be increasing
fuzziness/static in display, though nothing too seriously. Black is no
longer quite so black.

-- The complete fuzzout seems to be driven by something else, like it has
to be on for an hour and then it's constant.

I thought this was a problem with the vertical hold circuitry, but the
fuzzout with sound is completely throwing me for a loop. That makes me
wonder if there's a heat/dust problem going on.

Any advice would be greatly appreciated. I'm of the mind to try a vacuum,
canned air and some electric parts cleaner, but I'd love some direction
before I electrocute myself. =)


Mike


What's the brand and model? Is this by chance a GE/RCA/Proscan? If so then
resolder the tuner shield grounds. Otherwise, look elsewhere for cracked
solder joints. Don't use it again until you fix it, further damage is
likely.

Problems diagnosing TV
 

James Sweet wrote:
"Mike Stucka" wrote in message
...

Any advice would be greatly appreciated. I'm of the mind to try a vacuum,
canned air and some electric parts cleaner, but I'd love some direction
before I electrocute myself. =)

What's the brand and model? Is this by chance a GE/RCA/Proscan? If so then
resolder the tuner shield grounds. Otherwise, look elsewhere for cracked
solder joints. Don't use it again until you fix it, further damage is
likely.

Solder joints on any particular component, though?

Looks like it's an RCA F20631SE.

I think I just got a mild static shock turning the thing around with my
hand near the RCA plugs. I might've gotten the shock off a teddy bear
that's there, but I think it was the TV. Hrm.

Mike

Problems diagnosing TV
 

James Sweet wrote:
What's the brand and model? Is this by chance a GE/RCA/Proscan? If so then
resolder the tuner shield grounds. Otherwise, look elsewhere for cracked
solder joints. Don't use it again until you fix it, further damage is
likely.

Please disregard the earlier message. I'll try a fix this weekend, but
it sure looks like you nailed it right off the cuff. As weird as the
symptoms are, this seems to match up perfectly with the tuner shield
ground failu
http://www.audiokarma.org/forums/showthread.php?t=78503

James, you're a scholar and a gentleman. Thank you.


Mike

Problems diagnosing TV
 

Be advised, if you have not done any repairs on the RCA OBT circuits it may
be best to leave it to a professinal, or at least Google for the RCA On
Board Tuner repair hints. Doing it incorrectly will reneder the set a brick.
Cheers.
"Mike Stucka" wrote in message
...
James Sweet wrote:
What's the brand and model? Is this by chance a GE/RCA/Proscan? If so
then resolder the tuner shield grounds. Otherwise, look elsewhere for
cracked solder joints. Don't use it again until you fix it, further
damage is likely.

Please disregard the earlier message. I'll try a fix this weekend, but it
sure looks like you nailed it right off the cuff. As weird as the symptoms
are, this seems to match up perfectly with the tuner shield ground
failu
http://www.audiokarma.org/forums/showthread.php?t=78503

James, you're a scholar and a gentleman. Thank you.


Mike

Problems diagnosing TV
 

"Mike Stucka"
wrote in message ...

James Sweet wrote:
What's the brand and model? Is this by chance a GE/RCA/Proscan?
If so then resolder the tuner shield grounds. Otherwise, look elsewhere
for cracked solder joints. Don't use it again until you fix it, further
damage is likely.

Please disregard the earlier message. I'll try a fix this weekend,
but it sure looks like you nailed it right off the cuff. As weird as
the symptoms are, this seems to match up perfectly with the
tuner shield ground failu
http://www.audiokarma.org/forums/showthread.php?t=78503


I'd like to start a side discussion on this.

Many years ago I briefly attended RCA Institutes in New York. I had a mild
argument with one of the instructors, taking the position that theory was
the most-important thing, that a good tech should have a sound understanding
of electronics. (RCA taught many subjects at a college level.) He, on the
other hand, averred that technicians should learn and work by rote.

40 years have not changed my views on this matter. But it is true that any
good technician knows hundreds of things he learned only by practical,
real-world, day-to-day experience, stuff that didn't come out of a book. One
of the reasons I like reading the threads in this group is adding to my
repository of such information.

I'm coming to a point, so hang on.

When I see the OP's symptoms -- which pointed to vertical sync problems --
resolved by fixing a cracked solder joint on the tuner shield -- I can only
wonder in amazement. How did anyone ever figure that out? Or was it a case
of a part-by-part visual examination of the entire set when nothing else
worked? Broadly speaking... how does anyone go about "rationally" analyzing
such problems?

When I was a kid, I read "Mac's Service Shop" and similar short stories in
Popular Electronics and Popular Science. Back then, intractable problems
were called "tough dogs". Given the greatly increased complexity of modern
electronics, they're more like "rabid wolves".

PS: One of my high school friends was very much against "book learning". We
were trying to repair a TV in electronics shop at around the time I was
working through Milton S. Kiver's "Television Simplified". I had just read
the chapter on sync, and had a good idea which component was defective. My
friend was rather surprised when that component turned out to be the bad
one.

The advantage of "book learning" is that it gives one a framework on which
to hang all his practical experiences.

Problems diagnosing TV
 

how does anyone go about "rationally" analyzing such problems?

See the cracked solder spots .

Problems diagnosing TV
 

How does anyone go about "rationally"
analyzing such problems?

See the cracked solder spots.

But that's part of the issue. A close visual inspection can be useful, but
it consumes a lot of time and is not "rational" -- that is, it doesn't
connect symptoms with possible causes. It's more an act of desperation.
(That is not an implied criticism. I'm a great believer in the "try
anything" approach to servicing, and often have to fall back on it myself.)

Problems diagnosing TV
 

"William Sommerwerck" wrote in message
...
How does anyone go about "rationally"
analyzing such problems?

See the cracked solder spots.

But that's part of the issue. A close visual inspection can be useful, but
it consumes a lot of time and is not "rational" -- that is, it doesn't
connect symptoms with possible causes. It's more an act of desperation.
(That is not an implied criticism. I'm a great believer in the "try
anything" approach to servicing, and often have to fall back on it
myself.)



With a good eye, one can scan a whole board fairly quickly for cracked
soldering, and combined with poking and prodding a live set with an
insulated stick can help to narrow it down. Once you've seen a few of these,
it becomes a matter of Ok this is another one of these sets, better resolder
the tuner grounds and see where that gets me. Once I started repairing CRT
displays, I found that most of them started to look pretty much the same on
the inside, and the same half dozen or so problems crop up on 95% of the
defective units.

Problems diagnosing TV
 

Popular Science magazine used to have articles in Popular Science every
month by a radio tv repairman guy in New York City.Not sure if I
remember his last name, Art Margulis, something like that.I still have
some of those old Popular Science magazines around here somewhere.I used
to read his articles every month.His articles were always amusing, sort
of like the Gus Wilson Model Garage monthly articles that used to be in
Mechanix Illustrated magazine and the Tom ''Chrome Dome'' McCahill auto
road test articles in Mechanix Illustrated.
cuhulin

Problems diagnosing TV
 

wrote in message
...

Popular Science used to have monthly articles by a TV
repairman. Not sure if I remember his last name, Art
Margulis, something like that.

Art Margolis. Thanks for reminding me. He seemed to know what he was talking
about.

Problems diagnosing TV
 

Assuming you are soliciting opinions on this...

It seems to me that the answer to the question: "Which is more
important,
a thorough understanding of electronics or a great deal of
experience?"
depends upon the stated goal.

If the goal is to (eventually) be able to troubleshoot and repair
anything
that comes in the door, then I would cast my vote for technical
knowledge. For instance, in the case of the OP's problem, it would
seem to me that if poor solder joints on the tuner shielding are
really the problem, given a thorough understanding of how all the
circuitry works, one should be able to use a scope to examine
signals at various points and eventually ascertain that the tuner's
output is floating or whatever. (This is just an example, let's not
get into issues about whether or not one can probe into a tuner
and even see the actual signals.) So let's say for example it
took 2 hours of troubleshooting to find it.

OK, so now let's say that the goal is to be able to quickly and
profitably repair the majority of products customers are likely
to have - then it would seem that experience would be at least,
if not more, important. If I get 10 sets in a row like the OP's,
and I have a less thorough electronics background, it might
take me 3 or 4 hours to fix the first one. But I'll be able to
repair the next 9 in 1/2 hour.

OK, there's my two cents. If this was ridiculously obvious,
my apologies.

Problems diagnosing TV
 

Actually, Gus Wilson's Model Garage articles were in Popular Science
magazines.It's been a long while, I sort of forgot.I remember one time a
customer's tube type car radio (Model Garage article) was making a
buzzing/huming noise.Gus Wilson removed the buzzer and he temporaily
connected it to 115/120 volts AC current.That fixed the buzzer.
cuhulin

Problems diagnosing TV
 

"Mr. Land" wrote in message
...

Assuming you are soliciting opinions on this...

It seems to me that the answer to the question: "Which is more
important, a thorough understanding of electronics or a great deal
of experience?" depends upon the stated goal.

That wasn't exactly the issue. It was really "How in the name of heaven does
someone resolve a problem when the defective component has no apparent
connection with the problem?"


If the goal is to (eventually) be able to troubleshoot and repair
anything
that comes in the door, then I would cast my vote for technical
knowledge. For instance, in the case of the OP's problem, it would
seem to me that if poor solder joints on the tuner shielding are
really the problem, given a thorough understanding of how all the
circuitry works, one should be able to use a scope to examine
signals at various points and eventually ascertain that the tuner's
output is floating or whatever. (This is just an example, let's not
get into issues about whether or not one can probe into a tuner
and even see the actual signals.) So let's say for example it
took 2 hours of troubleshooting to find it.

In this case, why should bad solder joints on the tuner case produce these
visible effects? All the book-learning is not going to help much.


OK, so now let's say that the goal is to be able to quickly and
profitably repair the majority of products customers are likely
to have - then it would seem that experience would be at least,
if not more, important. If I get 10 sets in a row like the OP's,
and I have a less thorough electronics background, it might
take me 3 or 4 hours to fix the first one. But I'll be able to
repair the next 9 in 1/2 hour.

My attitude -- as a degreed EE -- is that I want to _understand_ what the
problem is. But it can take hours to figure out exactly what's going on.
Often, intelligent shot-gunning will get the unit up and running far faster
than meticulous analysis. Any successful service tech has to get those sets
in and out quickly if he's going to stay in business.

Problems diagnosing TV
 

wrote in message
...

Actually, Gus Wilson's Model Garage articles were in Popular
Science. It's been a long while, I sort of forgot. I remember one
time a customer's tube car radio was making a buzzing/huming
noise. Gus Wilson removed the buzzer and temporaily connected
it to 120 volts AC.That fixed the buzzer.

By buzzer, I assume you mean vibrator.

Problems diagnosing TV
 

Yep, the vibrator.Gus Wilson's Model Garage and Art Margolis articles in
those old Popular Science magazine articles I used to read.You can read
a lot of those Gus Wilson's Model Garage articles on the net.I guess it
is like that married Irish woman way over yonder across the big pond
once told me, I am getting old and senile.
cuhulin

Problems diagnosing TV
 

"William Sommerwerck" wrote in
:

In this case, why should bad solder joints on the tuner case produce
these visible effects? All the book-learning is not going to help much.

Perhaps the tuner case provides a good ground path for a bypass capacitor
in the vertical sync circuit?





--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

Problems diagnosing TV
 

bz writes:

"William Sommerwerck" wrote in
:

In this case, why should bad solder joints on the tuner case produce
these visible effects? All the book-learning is not going to help much.

Perhaps the tuner case provides a good ground path for a bypass capacitor
in the vertical sync circuit?

No need to speculate on this one.

See: http://www.repairfaq.org/sam/rcatune.htm

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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: Anything sent to the email address in the message header above is
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subject line. Or, you can contact me via the Feedback Form in the FAQs.

Problems diagnosing TV
 

"Sam Goldwasser"
wrote in message
...
bz writes:

"William Sommerwerck" wrote in
:

In this case, why should bad solder joints on the tuner case produce
these visible effects? All the book-learning is not going to help much.

Perhaps the tuner case provides a good ground path for a bypass
capacitor in the vertical sync circuit?

No need to speculate on this one.


Thanks for the information. I'm glad to see there was a class-action suit.

But the speculation remains. There is (for me) no obvious connection between
bad solder joints in the tuner shield and the symptoms described.

All the more need for open-mindedness when working on a product, and a
willingness to "try anything".

Problems diagnosing TV
 

The tuner shield was the ground return path for several critical
circuits.


On Dec 8, 10:52 am, "William Sommerwerck"
wrote:
"Sam Goldwasser"
wrote in ...

bz writes:
"William Sommerwerck" wrote in
m:
In this case, why should bad solder joints on the tuner case produce
these visible effects? All the book-learning is not going to help much.
Perhaps the tuner case provides a good ground path for a bypass
capacitor in the vertical sync circuit?
No need to speculate on this one.

Thanks for the information. I'm glad to see there was a class-action suit.

But the speculation remains. There is (for me) no obvious connection between
bad solder joints in the tuner shield and the symptoms described.

All the more need for open-mindedness when working on a product, and a
willingness to "try anything".

Problems diagnosing TV
 

"
wrote in message
...

The tuner shield was the ground return path for several
critical circuits.

Ouch. Thanks.

This is a rhetorical comment... That sounds like poor design.

This is a rhetorical question... How is the service tech supposed to know
this?