Board # 3141vmnp478, Zenith has listed as module level repair only.

We bought over 40 of these last year and they are now out of warranty.
During warranty approximately 50% of them failed with the same symptom:
Bottom half of picture was stretched and distorted in two or three
distinct bands with black lines of varying size. The odd part is the
black lines get wider toward the right side of the screen.

Have already esr checked all capacitors in the vertical and jungle ic.
Jumped across all capacitors in vertical. The distortion is clearly
visible in all the vertical waveforms, including the drive out of the
jungle, but the jungle usually has a feedback line so it may or may not
be the jungle or the output circuit.

No service manual on hand. The information available is limited to the
installers menu. We have tried to order and get a service manual out
of Zenith for several months and it has not been forthcoming.

Has anyone seen a similar odd vertical looking problem on the latest
model Zenith/Goldstar sets and found the problem? If so what was it.

TIA David

On 12 Jul 2005 13:03:48 -0700, wrote:

Board # 3141vmnp478, Zenith has listed as module level repair only.

We bought over 40 of these last year and they are now out of warranty.
During warranty approximately 50% of them failed with the same symptom:
Bottom half of picture was stretched and distorted in two or three
distinct bands with black lines of varying size. The odd part is the
black lines get wider toward the right side of the screen.

Have already esr checked all capacitors in the vertical and jungle ic.
Jumped across all capacitors in vertical. The distortion is clearly
visible in all the vertical waveforms, including the drive out of the
jungle, but the jungle usually has a feedback line so it may or may not
be the jungle or the output circuit.

No service manual on hand. The information available is limited to the
installers menu. We have tried to order and get a service manual out
of Zenith for several months and it has not been forthcoming.

Has anyone seen a similar odd vertical looking problem on the latest
model Zenith/Goldstar sets and found the problem? If so what was it.

TIA David

One thought, and it's a reach...does the vertical IC have +/-
supplies?

Tom

Single supply. Uses TDA8174 vertical output ic.

One thought, and it's a reach...does the vertical IC have +/-

RCA has a Model or two that has + and - supplys
that did the same drove me nuts till I got the service manual.

kip


supplies?

Tom

Definitely single supply as pin 6 is tied directly to ground. Looking
at the typical schematic for the ic, and the fact that all the
capacitors esr ok and no change when jumping them, I suspect the ic
itself is bad. It looks like the ic has been running quite hot for a
while.

David:
I had one here several months ago, not exactly the same symptoms you
described.... it turned out to be a leaky diode near the TDA8174.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


wrote in message
ups.com...
Board # 3141vmnp478, Zenith has listed as module level repair only.

We bought over 40 of these last year and they are now out of warranty.
During warranty approximately 50% of them failed with the same symptom:
Bottom half of picture was stretched and distorted in two or three
distinct bands with black lines of varying size. The odd part is the
black lines get wider toward the right side of the screen.

Have already esr checked all capacitors in the vertical and jungle ic.
Jumped across all capacitors in vertical. The distortion is clearly
visible in all the vertical waveforms, including the drive out of the
jungle, but the jungle usually has a feedback line so it may or may not
be the jungle or the output circuit.

No service manual on hand. The information available is limited to the
installers menu. We have tried to order and get a service manual out
of Zenith for several months and it has not been forthcoming.

Has anyone seen a similar odd vertical looking problem on the latest
model Zenith/Goldstar sets and found the problem? If so what was it.

TIA David

Was it a Zenith? Which diode location? Remember your model #?
As the tv runs longer the symptom kind of changes, the lines move
closer to the top, and it looks like the scan lines are not going
straight and are folded over.

It was definitely a Zenith.... It was the same vintage 20" 2004. I have
been digging through my service records and can not find the details.....
yet.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - -


wrote in message
oups.com...
Was it a Zenith? Which diode location? Remember your model #?
As the tv runs longer the symptom kind of changes, the lines move
closer to the top, and it looks like the scan lines are not going
straight and are folded over.

How good is your memory?
I see three close diode, the vertical ramp pump up diode that looks
like a regular black diode tied to the vertical vcc. I also see two
little glass diodes between the vertical ic heatsink and the flyback,
one is right next to the heatsink, one is a little farther away.

On 12 Jul 2005 14:21:40 -0700, put finger to
keyboard and composed:

How good is your memory?
I see three close diode, the vertical ramp pump up diode that looks
like a regular black diode tied to the vertical vcc. I also see two
little glass diodes between the vertical ic heatsink and the flyback,
one is right next to the heatsink, one is a little farther away.

FWIW, here is a datasheet for the TDA8174:
http://www.promelec.ru/pdf/1232.pdf

There is an application circuit on page 3.


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

Try the black diode by the vertical IC,
1N4007 or close to that #, may be the
IC too, but try the diode first, Rono.

David

There is a Field Service Bulletin on this problem.

Replace C2106 0.1uf 50V

It is located at the rear of the chassis behind the heat sink for the
vertical IC.

Hope this solves your problem.

David, on the Illinois prairie.

Thanks for the reply. I will be back into this one early next week and
will report back the results.
David


wrote:
David

There is a Field Service Bulletin on this problem.

Replace C2106 0.1uf 50V

It is located at the rear of the chassis behind the heat sink for the
vertical IC.

Hope this solves your problem.

David, on the Illinois prairie.

Thanks, fixed the problem.
Now to find out why Zenith would not simply either concede they had a
problem or give me the information.