Zenith Pip System 3, blank screen, but sound and menu work

[majesus]

I got a Zenith TV with a blank screen problem.

WHen cold, the TV would start fine, then after a few minutes, th
picture would blank out (a blank screen.) The sound still works, an
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 th
tv. The blank screen would come on intermittently.

Well tonight, the picture went blank, and I couldn't get it back on. S
I let the TV sit off for 20min off while I did some googling on the ne
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 t
get a picture back since.

I am thinking it is a bad cap (just a case), I'll take it apar
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

 

[Art]

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]

Thanks for the info

Can I get a schematic for it to trace the inputs/outputs of the Vide
circuit?
Here is some more info if it helps:
Service Manual CM-147/C-11(A)
Chassis (C11 from Z-tips). The Main board has a sticker with: 9-1551
Thanks
majesus18 @ gmail.co

 

[R!]

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!!

 

[majesus]

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, everythin
looked fine. So I did a wiggle test by turning the TV on and tappin
and shaking DL2200 with a wooden spoon. Nothing happened. But when
started doing some measurements with my scope, as I touched pin2 wit
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 th
problematic area. The TV works great now. I'm very pleased.

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

For other people/members, here is a schematic I used. It has a simila
comb filter and is good starting point ot give you an idea on how th
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

[image
http://i48.photobucket.com/albums/f223/majesus/coupons for rfd/DL2200.jpg