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New success: Banging TV brings picture back. Any insight?

I made a post on the 6th about a new to me panasonic TV having a picture problem, with the picture fading out and back in. Thanks to all who replied. It's black video for the most part but I believe I found a way to bring the video back. If I bang moderately on the top of the TV (from above the glass to the back) I was able to successfully get the picture back three times within two minutes. Two times the picture faded right back out after a few seconds and the third time it's been on and perfect for about 10 minutes now. When it works then fades out, it fades out without being touched at all so it's not due to a physical problem like a loose item.

Does anyone have any thoughts? Does the banging on the top offer any new insight to the problem along with my other post? Again, there were no apaprent problems I could see inside regarding solder joints. I ensured that all the wiring connectors were securely plugged in.

What is my bloody problem with this! I can't throw it out because it clearly does work still! I just want to be able to get it to stay working!

Aloha Brian

Reply to
Brian
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Reply to
Art

Brian, When someone says "fade" that usually implies it takes time for the picture to go away and come back rather than abruptly disappearing and reappearing. I would check the filaments of the picture tube to see if they darken as the picture goes away. If so, trace the wires from the CRT board down to the chassis to check or just resolder all the connections. CRT filaments are usually powered by the flyback. "Percussive diagnostics" shows you there is an intermittant connection. Next step: fix it.

Ray

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Reply to
Ray

It is probably a cold solder joint, tiny crack in a board or similar loose connection in the filament circuit. There should be 2 pins on the CRT marked "heater" or "filament" Follow these from the CRT to the board. Follow the traces on the boards to their source and all associated components. You may have to search with a magnifying glass or gently flex the board or tap components with an insulated prod such as a screwdriver handle with the power on. Be careful, be safe, and good luck

Reply to
Jumpster Jiver

A lot of times the solder on the CRT board itself is pretty light, and prone to failure.

Tom

Reply to
Tom MacIntyre

It's obviously a solder joint, you haven't looked hard enough.

Reply to
James Sweet

What would one look like? All the solders I've seen are perfect little dabs of solder. I re-soldered the 6 or 7 behind the filament two of which are for the heater with no success.

Aloha!

Reply to
Brian

look again. there will probably be some bad soldering somewhere, usually on the main board or one of the LOPTX pins.- try removing the crt neckboard and putting it back on again - could be the crt socket at fault.

Reply to
b

Thanks guys. I checked the voltages behind each and every pin going to the filament and they are all getting their power which makes me think the problem as from the filament onward.

Is there a way to test the filament bulb itself? How about from the bulb onward?

Brian

Reply to
Brian

Brian, I worked on a Hitachi that had a very similiar problem, and could be temporarily fixed by smacking the set. I found a bad solder joint on the horizontal driver transformer. This repaired it. Look closely at all solder joints. This particular joint had a hair line crack in it. Good luck.

Reply to
Golf

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