Sony KV-36V32 Horiz problem; experienced only please

[Daryle Brooks]

I would go about resoldering all the joints in those areas you deem
would affect the symptom.If that does not solve the problem,then move
on to solder joints around other hv areas and the vertical output
chip.One circuit can affect another. I tend to overshoot the simple
problems,looking for the tough dog.Remember,it's a good idea not to
light a match until you know which end of the dog is barking. I am
currently working on a Toshiba with somewhat similiar symptoms.a lot
of components on this 9301 board/boards look like they're soldered
correctly but are not. Good Hunting.

Daryle
WB7TNE
Cher <ccher@your.place> wrote in message
news:<gcqq20pi2mdn8rsaspq317sf3t9k9k4lnl@4ax.com>...

I have a KV-36V32. It has a problem similar to a few other posts
Let me describe it to you. If you have seen it maybe you can help.

From cold start everything is fine. After a while it appears as if
there is an intermittent short in the horiz yoke. The pic is fine at
the top. 2/3 down the scan lines taper vertically from the sides and
are random length. The pic will eventually go dark but the sound will
remain on. There is no audible arcing sound, but then my hearing ain't
what it used to be.

If I tap ANYWHERE on ANY circuit board I can create the problem within
30 seconds after a cold start. It is not sensitive to moving the ckt
bd, only tapping on it or a component.

I tried this VERY carefully in an attempt to localize it but it
appears equally sensitive anyplace and on any component including the
FBT, the PS bd, the front panel button bd, and even the HV anode lead
near the FBT

There is no sensitivity on the CRT or the video drive BD on the pic
neck.

A last clue. Sometimes when is reacts it will do so with a total red
screen (as in a CRT screen short or a loss of screen volts on the red
gun), but it does not shut down.

It does get more sensitive the longer it is on, requiring lighter taps
to cause it to happen.

My guess is that a component has a mechanical defect that actually has
a resonant frequency causing it to react to any vibrations (tapping)
which is why the part does not need a direct hit.

Maybe the red screen will point to the right part, but I don't have a
schem.

Thanks

bill

 

[Cher]

Good points - thanks

I guess I would feel better doing it on my bench where I have the
tools to look at it, than on his floor.

On Thu, 19 Feb 2004 06:40:58 -0500, "Leonard Caillouet" <no@no.com>
wrote:

Cherie, you said, "It appears that no one has experienced it, so a part by
part replacement seems like the only thing to solve it."

That, IMO is a rather poor approach for someone who has the experience that
you purport to have. You were given some suggestions to point you in the
right direction, and since the problem is at least a bit less trivial than,
for instance, a Toshiba two cap vertical symptom-repair solution, the only
reasonable approach is some actual troubleshooting.

You were told by guys that have lots of experience with the problem exactly
what any of us would do and your initial subject line and subsequent posts
have seemed like posturing, as Sofie put it. You got the experience you
asked for and need to use it.

Resolder everything in the horizontal drive and output circuits, check the
electrolytic caps in the circuit, inspect all of the heat producing
components in the set for bad solder joints. Get out your scope and
troubleshoot it. Any good, experienced technician knows that the first
thing you have to do is to go back over your assumptions and realize that if
you are not getting anywhere on a problem that you made a bad one somewhere.
In this case you likely assumed that a joint was good when it was not, or
assumed that a area was unrelated when it was significant. There are no
easy, one-shot solutions in many repairs and "experienced" people are not
the only ones who know this.

Leonard Caillouet

"Cher" <ccher@your.place> wrote in message
news:he7830hb03g0e09i2nfjb0pterdcu3fh13@4ax.com...
Lenny, that is the kind of answer I was hoping to avoid.

If you have something positive to offer, please do.

Your comment implies that anyone who asks for help is an idiot and
can't troubleshoot their way out of a paper bag, and probably that is
true for a large majority of them. You can tell by the level of detail
that is submitted - "My TV won't come on" - at least I can.

I would love to help people out in this newsgroup. But most of them
don't post the detail I have and it would take a week to get them to
give me enough information for me to even start. So unless one is
willing to hold someones hand and walk them thru it only to find they
have no ability to fix the problem, why must people try to push
themselve up on a pedistal by knocking others and down giving them
hot air advice? - "Take it to a qualified shop" or "Ever consider a
few minutes of skilled troubleshooting?"


On Wed, 18 Feb 2004 07:15:03 -0500, "Leonard Caillouet" <no@no.com
wrote:


"Cher" <ccher@your.place> wrote in message
news:u9q530tb03s37n74hp3r1llvq4vkhgi6ts@4ax.com...
Thanks for the advice John, but I don't think I qualify as a layman.
I owned a shop fixing anything that walked in (TV, Stereo, CB, VHF,
CATV, Instruments, etc.) and as an engineer I managed 25 techs
repairing any kind of industrial control equipment you can think of.
I've repaired more different types of equipment than you have
different manufacturers of home electronics. I have one of the first
issued ET licenses in the state of NH with a radar endorcement, I have
my FCC General class license. I repaired eletronic warfare equipment
in the Army and obtained a P2 (highest) proficiency.

I am fully aware of what a problem like this involves and I ask for
experience for that reason. With my experience, I couldn't tell you to
do any more than I have done and it won't point me in a definitive
direction. You have to have experienced it to help.

It appears that no one has expereinced it, so a part by part
replacement seems like the only thing to solve it. Since it is my
freinds TV, I guess I won't be doing that.

Ever consider a few minutes of skilled troubleshooting? With the
experience
you have you should be able to do so. With the experience that has been
offered in this group and a little troubleshooting you could probably
solve
the problem.

Leonard Caillouet

 

[Cher]

thanks Daryle.
I think the best way to eliminate the solder issue is to resolder the
whole board (or all three).
If it is a solder break it is too small to see - but then my eyes
ain't what they used to be.

anyway, he tells me it is totally dark now and doesn't even come on
momentarily - maybe I can find it now.

On 19 Feb 2004 13:07:07 -0800, wb7tne350@hotmail.com (Daryle Brooks)
wrote:

I would go about resoldering all the joints in those areas you deem
would affect the symptom.If that does not solve the problem,then move
on to solder joints around other hv areas and the vertical output
chip.One circuit can affect another. I tend to overshoot the simple
problems,looking for the tough dog.Remember,it's a good idea not to
light a match until you know which end of the dog is barking. I am
currently working on a Toshiba with somewhat similiar symptoms.a lot
of components on this 9301 board/boards look like they're soldered
correctly but are not. Good Hunting.

Daryle
WB7TNE
Cher <ccher@your.place> wrote in message
news:<gcqq20pi2mdn8rsaspq317sf3t9k9k4lnl@4ax.com>...
I have a KV-36V32. It has a problem similar to a few other posts
Let me describe it to you. If you have seen it maybe you can help.

From cold start everything is fine. After a while it appears as if
there is an intermittent short in the horiz yoke. The pic is fine at
the top. 2/3 down the scan lines taper vertically from the sides and
are random length. The pic will eventually go dark but the sound will
remain on. There is no audible arcing sound, but then my hearing ain't
what it used to be.

If I tap ANYWHERE on ANY circuit board I can create the problem within
30 seconds after a cold start. It is not sensitive to moving the ckt
bd, only tapping on it or a component.

I tried this VERY carefully in an attempt to localize it but it
appears equally sensitive anyplace and on any component including the
FBT, the PS bd, the front panel button bd, and even the HV anode lead
near the FBT

There is no sensitivity on the CRT or the video drive BD on the pic
neck.

A last clue. Sometimes when is reacts it will do so with a total red
screen (as in a CRT screen short or a loss of screen volts on the red
gun), but it does not shut down.

It does get more sensitive the longer it is on, requiring lighter taps
to cause it to happen.

My guess is that a component has a mechanical defect that actually has
a resonant frequency causing it to react to any vibrations (tapping)
which is why the part does not need a direct hit.

Maybe the red screen will point to the right part, but I don't have a
schem.

Thanks

bill

 

[Cher]

thanks

he tells me it is always dark now - maybe I can find it now.
but then I will probably only find a lack of voltage caused by the
shutdown ckt response to the defect.

he may have to buy a schematic for this one.


On Wed, 18 Feb 2004 20:15:28 -0800, "Sofie" <sofie@olypen.com> wrote:

Cher / Bill:

Here is a repeat of my suggestion that would have you utilize an
OSCILLOSCOPE to narrow down your search for the faulty area of the
circuitry...... just blindly replacing any and every part is usually a
waste of time and money, particularly if it is not a part that is bad.
Remember to use an isolation transformer if you are probing "hot-ac line"
circuitry.

">I know that you have already tried and failed to localize the problem but
try again, this time focusing on selected areas of the circuitry...
starting
with power supply B+ distribution and flyback derived B+ sources.... if
you still have an oscilloscope from your "old" service days you might be
best advised to hook up your scope probes and monitor the ripple and
regulation of those distribution rails to see if they change with the
symptoms you described...... this just may help you to pinpoint the
problem
area of circuitry."

 

[Cher]

can't dismiss that for sure. I have ofen wondered why a tech chose a
particular coarse of action the proved successful.

I was just hoping someone had already suffered thru this.
next step I guess is to do a wholesale resolder - that will end that
issue.

The scoping trick may be just that since a problem like this will be
very difficult to pull out of the ground clutter. I imagine that noise
will be everywhere.


On Wed, 18 Feb 2004 18:50:01 -0800, "Sofie" <sofie@olypen.com> wrote:

Cher alias Bill:
From my experience with the techs in my shop....... there are times that my
best and most experienced techs get bogged down on a tough dog repair.
Occasionally a new or less experienced tech will give the problem a fresh
look and find the obvious, easier solution that the more experienced tech
didn't give much consideration to because he was looking for a more
complicated, hard to find fault..
I almost never ignore the novice repair suggestion....... I will always
listen to it and then chose to act on it or not. It's like eating a
chicken wing..... eat the chicken and spit out the bones.

 

[Cher]

there is alway a comedian in the group


On Thu, 19 Feb 2004 18:33:00 -0700 (MST), goodguyy@webtv.net (Ken G.)
wrote:

>Did you plug it in ?

 

[Cher]

This isn't going to go away anytime soon since the TV is 100 miles
away from me and I don't plan on going back soon, but I will let y'all
know how it turns out.


thanks

On Sat, 14 Feb 2004 00:42:21 GMT, Cher <ccher@your.place> wrote:

I have a KV-36V32. It has a problem similar to a few other posts
Let me describe it to you. If you have seen it maybe you can help.

From cold start everything is fine. After a while it appears as if
there is an intermittent short in the horiz yoke. The pic is fine at
the top. 2/3 down the scan lines taper vertically from the sides and
are random length. The pic will eventually go dark but the sound will
remain on. There is no audible arcing sound, but then my hearing ain't
what it used to be.

If I tap ANYWHERE on ANY circuit board I can create the problem within
30 seconds after a cold start. It is not sensitive to moving the ckt
bd, only tapping on it or a component.

I tried this VERY carefully in an attempt to localize it but it
appears equally sensitive anyplace and on any component including the
FBT, the PS bd, the front panel button bd, and even the HV anode lead
near the FBT

There is no sensitivity on the CRT or the video drive BD on the pic
neck.

A last clue. Sometimes when is reacts it will do so with a total red
screen (as in a CRT screen short or a loss of screen volts on the red
gun), but it does not shut down.

It does get more sensitive the longer it is on, requiring lighter taps
to cause it to happen.

My guess is that a component has a mechanical defect that actually has
a resonant frequency causing it to react to any vibrations (tapping)
which is why the part does not need a direct hit.

Maybe the red screen will point to the right part, but I don't have a
schem.

Thanks

bill

 

[Ken G.]

Did you plug it in ?