I got a Zenith TV with a blank screen problem.

WHen cold, the TV would start fine, then after a few minutes, the picture would blank out (a blank screen.) The sound still works, and the menu, volume, channel info can still be displayed on the screen, but I have picture. The problem use to be fixed by powering off/on the tv. The blank screen would come on intermittently.

Well tonight, the picture went blank, and I couldn't get it back on. So I let the TV sit off for 20min off while I did some googling on the net searching for an answer (that's how I found this forum.)

After 20min, when I turned the TV on, it worked for another 10minutes, then went out blank again after a minute or so. I haven't been able to get a picture back since.

I am thinking it is a bad cap (just a case), I'll take it apart tomorrow and test some di-electric caps around the board with my scope.
Anyone have suggestions that maybe the cause of the problem?

The Zenith TV is a PIP SYSTEM 3, Model SR2573DT, serial 522-454-80230. It was built in 1995.

Thank you.

Suspect failure in video processing circuit, get out the scope and trace the
video from the demodulation circuits through to the jungle ic. Other
alternative is send the main board into PTS for rebuilding.
"majesus" wrote in message
...

I got a Zenith TV with a blank screen problem.

WHen cold, the TV would start fine, then after a few minutes, the
picture would blank out (a blank screen.) The sound still works, and
the menu, volume, channel info can still be displayed on the screen,
but I have picture. The problem use to be fixed by powering off/on the
tv. The blank screen would come on intermittently.

Well tonight, the picture went blank, and I couldn't get it back on. So
I let the TV sit off for 20min off while I did some googling on the net
searching for an answer (that's how I found this forum.)

After 20min, when I turned the TV on, it worked for another 10minutes,
then went out blank again after a minute or so. I haven't been able to
get a picture back since.

I am thinking it is a bad cap (just a case), I'll take it apart
tomorrow and test some di-electric caps around the board with my scope.

Anyone have suggestions that maybe the cause of the problem?

The Zenith TV is a PIP SYSTEM 3, Model SR2573DT, serial 522-454-80230.
It was built in 1995.

Thank you.




--
majesus

Thanks for the info

I would be extremely appreciative if I can get a schematic (or service model) for this tv model (or chassis) so I can trouble shoot the video signal circuit.
If it helps, the Service Manual number is CM-147/C-11(A)
The Chassis is C11 (info obtained from Z-tips). The Main board has a sticker marked: 9-1551
Thank you
majesus18 @ gmail.com

majesus wrote in
:


I got a Zenith TV with a blank screen problem.

WHen cold, the TV would start fine, then after a few minutes, the
picture would blank out (a blank screen.) The sound still works, and
the menu, volume, channel info can still be displayed on the screen,
but I have picture. The problem use to be fixed by powering off/on the
tv. The blank screen would come on intermittently.

Well tonight, the picture went blank, and I couldn't get it back on.
So
I let the TV sit off for 20min off while I did some googling on the
net
searching for an answer (that's how I found this forum.)

After 20min, when I turned the TV on, it worked for another 10minutes,
then went out blank again after a minute or so. I haven't been able to
get a picture back since.

I am thinking it is a bad cap (just a case), I'll take it apart
tomorrow and test some di-electric caps around the board with my
scope.

Anyone have suggestions that maybe the cause of the problem?

The Zenith TV is a PIP SYSTEM 3, Model SR2573DT, serial 522-454-80230.
It was built in 1995.

Thank you.





I had a lot of problems with the voltage regulator and bad solder
connections in the pip modules. Some of them can be troubleshot by using
one of the video jumper interconnects to temporarly bypass the pip
module. You would need a diagram to find these the Y (brightness) and C
(color) are looped through the pip module,

Y------- ------- Y
CH - PIP - CH
C------- ------- C

The above is greatly simplified...

R!!

Found it!!! THanks guys for the help.

It was the Comb Filter which is part of the video's circuitry. Initially, on my first examination of the component DL2200, everything looked fine. So I did a wiggle test by turning the TV on and tapping and shaking DL2200 with a wooden spoon. Nothing happened. But when I started doing some measurements with my scope, as I touched pin2 with the probe's tip. The picture on the TV screen came back on. AHA! SUCCESS!!!

So I resoldered all five pins of DL2200 as well as others around the problematic area. The TV works great now. I'm very pleased.

If anyone does have the service manual (or any other relevant schematic) for chassis C-11. I would thank you immensly if you could email it to me (majesus18 at gmail.com). I would like to have it for reference in case I ever need it again.

For other people/members, here is a schematic I used. It has a similar comb filter and is good starting point ot give you an idea on how the circuit is setup. FYI, this circuit is for chassis CS, models: H27E46DT, H27E46DT8, H32E46DT & H36E46DT.

Going to go watch a movie on my fixed TV.
Cheers,
Maj