Question about Televison & Video
I am a Major Appliance Servicer for 29 years, but TV's are not my forte, although I feel very qualified to make a repair. I will try to explain the problem as best I can.
I have a Panasonic 2000 model PT-51HX40B that has a shutting off problem, along with blue convergence issues. The set shuts itself off, and directly seemed to be related to the volume level. If the volume was turned up to maybe create a little more bass reverb (level15) the set would shut off after a few minutes. I removed the back and cleaned the dust off of all of the circuit boards, cleaned mirror, lenses and inside screen, and checked connections. I didn't really find any bad connections, and I turned on the set and watched and listened to what was happening. When the volume is turned up, on what I would call the power supply board, there was what sounded like a relay that would click in and out irradically. This would not alter the picture, but eventually the relay would click about 20 times, then the set would go black. It sounded as though it was still powered up, but I would here the sound of things cooling down. I noticed a heat discoloration on a circuit board (TNPA1412) around what looks to be a diode (has an S,G,and D on the board where the three terminals of the part are soldered). I found that if I put a pressure on the circuit board, pushing it towards the front of the set, that this seemed to cause a resetting of something on the power supply board, and I could then turn the machine back on with the remote. I removed the TNPA1412 board and inspected it, finding nothing obvious, reinstalled it and it continued to act the same way. I eventually cable tied the upper corner of that board to some metal framework in front of the board, causing a slight pull on the board, and tried it out. The set hasn't shut off by itself since (4 days), and I have cranked the volume quite loud. I know it sounds like a connection issue, and my cable tie isn't a permanent fix, but if it is working is there anything that should be done?
I also seem to have a problem with the blue convergence. If I center the blue convergence in the center of the screen, the extreme right side 4 inches has a tendency to have a blue shadow to the left of any vertical black object, and the extreme left side 4 inches of the screen has the blue shadow on the right side of the vertical black objects. I have to find a happy medium and live with it for now. I also have blue shadowing horizontal objects on the very extreme top and bottom. Any ideas?
The picture is plenty viewable, but my eyes keep catching the glimpses of blue on the ouside edges. If there is a fix that isn't too costly, or any help ideas out there, I would very much appreciate any information on this subject.
1) Definitely a bad solder connection..I use a magnifier...
2) Blue convergence IC bad....change both for reliability
Located on large heatsinks on main PCB.......
Check B+ resistors for over-heating...............................T.
Posted on Feb 06, 2008
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Posted on Jan 02, 2017
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