Hello

I have a Zenith TV. Model ZB2771h. The picture takes up only about half of the screen now, and it has gotten worse over time. I noticed before that as the TV warmed up, it grew from about 1/3 of the screen to about 2/3 of the screen. I have replaced the capacitors around IC2100, but it did not change anything. I did find one bad capacitor.

Also. I can not find a schematic anywhere online. Any ideas?

Does anyone have any ideas as to what else I should do.

Thank You

The Smoker King

Hello,
Are the black spaces above and below the visible screen parallel? If
they look keystone, you may have a bad deflection yoke. Also, what is
the actual service model number and manufacture date on the set? With
this info [white sticker on back of set], I can check history on the
chassis and get back to you.
friend

The Smoker King wrote:
Hello

I have a Zenith TV. Model ZB2771h. The picture takes up only about
half of the screen now, and it has gotten worse over time. I noticed
before that as the TV warmed up, it grew from about 1/3 of the screen
to about 2/3 of the screen. I have replaced the capacitors around
IC2100, but it did not change anything. I did find one bad capacitor.

Also. I can not find a schematic anywhere online. Any ideas?

Does anyone have any ideas as to what else I should do.

Thank You

The Smoker King


--
The Smoker King

Here are the numbers and manufacture date off of the back of the TV.
Model No. ZB2771h
Service No. ZB2771h
Serial No. 891-44300092
Manufatcured: July, 1988

Also, the lines are parallel. About 1-2 inches of black space and color lines above the screen, and about 8 inches of black below the viewable screen.

Thanks Again.

Usually caused by electrolytic capacitors in the scan amplifiers, and power
supply that are failing over time. As they age, they can become thermo
sensitive. With proper troubleshooting and with the proper experience, the
set can be serviced.

--

JANA
_____


"The Smoker King" wrote in message
...

Hello

I have a Zenith TV. Model ZB2771h. The picture takes up only about
half of the screen now, and it has gotten worse over time. I noticed
before that as the TV warmed up, it grew from about 1/3 of the screen
to about 2/3 of the screen. I have replaced the capacitors around
IC2100, but it did not change anything. I did find one bad capacitor.

Also. I can not find a schematic anywhere online. Any ideas?

Does anyone have any ideas as to what else I should do.

Thank You

The Smoker King


--
The Smoker King

The ZB series was the special Bose sound model, service info on them is
nearly non existant. Have you replaced both the 33uf and 47uf caps that
sit next to IC2100? These fix the problem most the time. Other
possibilitys include a bad or corrupted eprom IC or IC2100. This is the
Zenith digital chassis I believe. If so, it was about the first design
that used the bus controlled adjustments for height ect, instead of the
old pots. If this set uses a TDA8175 (221-384) for IC2100 be aware it
is no longer available if bad.

I have replaced both of those caps, and I found that a 100uf cap was bad, read about 67uf until I heated it up, then about 98uf. I noticed the (221-384) chip is not made any more, and I have cross-referenced it with another chip that might work.

Thank for your help.

Change electrolytics caps in the vertical

I have done that also. A buddy of mine tested the vertical signal coming into the board with an O-scope, and he said the signal is bad before the board.

The Smoker King:
Did your "buddy" with the O-scope then conclude that the jungle chip is
bad..... or another related failure.... or did he not conclude anything
about the real problem???
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
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"The Smoker King" wrote in message
...

Wrote:
Change electrolytics caps in the vertical


I have done that also. A buddy of mine tested the vertical signal
coming into the board with an O-scope, and he said the signal is bad
before the board.


--
The Smoker King

He did not conclude anything because he doesn't have the schematic and he never messed with the processor before.