Power supply failure and other problems

I've experienced what seems to be a combination of problems reported by others with this monitor unit: For the past year, occasionally I've see a "faded" patch of pixels at the top of the screen, near the center. Often this seemed to happen when a sold color was displayed in the area continuously (for example, during the Olympics soccer matches, when the green grass was continuously displayed in that area). Or it would appear where there might be a shiny patch on somebody's forehead. Turning off the monitor for awhile would alway help the problem go away. But I hadn't noticed this symptom recently... Just yesterday, I experienced a complete failure of the power supply. This occurred when turning the system on - mading a pretty loud POP. I've taken a look inside and see that a 0.1 ohm resistor (R133) blew. Also a 0.47 ohm resistor adjacent to Q127 and it's heat sink is toasted . I've tried testing the power connections to the large right (X DRIVE ASS'Y) and left (no obvious name) boards, but don't measure shorts - but maybe I'm not testing the right pins. I'm planning to replace the blown resistors, but am afraid there is a deeper problem which caused the failure in the first place. Any suggestions on more detailed analysis I can do to determine the root cause would be greatly appreciated!

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Tinu Patel

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See the pdf for the service manual here http://getmanual.ru/tv/sb/pioneer.pdf Have fun.

Posted on Sep 01, 2007

Anonymous

Where do you live. In new jersey? I maybe able to help you directly as I am an engineer like yourself. Usually low value resistors are the first to go because they cannot handle a power increase by much. This usually occurs because a power transistor is shorted causing more current flow to the biasing resistors. Is this problem on the main screen or the control box. Email me at [email protected]

Posted on Sep 01, 2007

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