Sep 1, 2016, 4:08 AM
Post #1 of 9
I guess it was inevitable that this would happen. I bought this TV new in 2008, and for most of those eight years it has ran 24/7 and never given me a minutes trouble, until three days ago when I fell asleep on the sofa watching TV and when I woke up, the TV was off and the red power indicator LED was blinking.
Panasonic TH-42PZ85U 11 blinks
I pushed the power button on the set, it came on for about 3 seconds, then shut off, the LED blinks 11 times, then pauses, then 11 more blinks, pause 11 more..etc.
I got on the Internet, discovered the "blink codes", and according to that info (SOS PB Board, Fan Control), so....being into hobby electronics, I took the back off the set and found the cooling fans to be absolutely caked in dust, but very little dust, if any at all, on the circuit boards. Using my little portable compressor, I blew all of the dust off the fans, and very gently and from a distance, off the circuit boards.
I thought that might have fixed it, but it's still doing the same thing. Push the button...comes on for 2 or 3 seconds....shuts off, then the 11 blinks.
I then removed the PB board, and visually inspected it, and from a visual standpoint, it appears to be perfect. The two 470uF electrolytic caps and the 100uH inductor all look fine. On the back of the board there are a bunch of surface mount resistors, capacitors and diodes, and a 4 pin + lead component. Everything looks good, no burnt traces or anything.
I haven't tested the fans yet. I have a benchtop power supply that I can use, but the TV is in the other room. I'll have to make some jumper leads that are long to reach in there. I have more than enough 26awg wire to do the job.
Now to my questions....
1.) Is this 11 blink code usually the PB board itself or just a faulty fan?
2.) If the PB Board DOES go bad, what is the culprit? Is it the little surface mount IC on the back of the board? The markings are 1CN38M, but it must be long obsolete, a google search turned up nothing. I couldn't find a datasheet. That device, whatever it is, is the only controller on the board, everything else is just passive.
3.) Maybe I'm over-thinking it. Do I just have a bad fan?
FIX IT!!! Don't throw it out. We have enough junk as it is.