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Zenith pict comes on bright then goes dark

Hi I was wondering if any of you have had any experience with Zenith H0958x or H09c59x 9" TVs. These TVs were also modified by a company called PDI for hospital TV usage (PDIZ9TV-B)but doesnt seem to be a problem in the modifications, I could be wrong though.

When first powered on the TV will come on full brightness then quickly fade to a very dim picture. The audio is ok as is the on screen displays but as I said the video get very dark, almost completly black on some. And on some of the TVs the brightness will return to normal after being on for about 3 or 4 min while others dont seem to ever come back up. But turning off tv then back on will continue to give the normal brightness good pict then fade away results until TV has "warmed up"

Also the voltage on the high voltage anode is still present. It seems to be something in the video chip and associated components since the on screen display and menu appear normally but I havent had any luck tracng the problem down.

I have recently inherited about 7 or 8 of those TVs so any help would be apreciated

Reply to
Vorlon
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Do those have the microprocessor PDI board in it? If so they have to be unlocked to allow video display via some computer code coming in through the cable.

Reply to
dkuhajda

These sets are only able to be activated by infared remotes and dont have the over the cable remote activation features. Once activated only chan vol and cc funtions can be accessed. Also I have a number of the same model purchased at the same time as the others that are working fine. And these TVs worked fine for a couple years until they developed the problems Now I am not ruling out a chip problem since the problem will either go away after being on for a few min or do the opposite and fade away after a few min. But the most common problem seems to be the come on for a second full brightness then dim down to a either very dark picture or completly black.

I contacted PDI and they are pointing me to a capacitor but after changing it out on 1 of the TVs (only had 1 cap lol) the problem didnt change.

Oh well back to proding and tracing to try to track it down with my poor schematic lol

Thank you very much for your responce, I appreciate any thoughts.

Reply to
Vorlon

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