Re: Samsung Plasma PS50C7790 with black screen but sound
Yes Va rises to 55V during startup and the TV is manufactured Aug. 2010.
After more internet research I found a way to determine which board is responsible for the problem:
Disconnecting the flat cable running from Logic Board to Y-Main or X-Main is a good way to find the source of the problem!
I did it like this:
1. Disconnect the TV from the mains
2. Disconnect the X-Mains flat cable running to the Logic Board, all other cables remain in the their respective positions
3. Connect TV to the mains and switch-on
4. On my TV the error (5s/1s toggle of LED) was still present, so the faulty Board is still detected which points to the Y-Main/Y-Buffer being the problem
5. Disconnect the TV from the mains
6. Disconnect the Y-Mains flat cable running to the Logic Board, all other cables remain in the their respective positions (re-connect the X-Mains flat cable to the Logic Board)
7. Connect TV to the mains and switch-on
8. On my TV the error (5s/1s toggle of LED) did NOT SHOW UP AGAIN but instead the other LED on the Logic Board now toggles in 1s/1s timing indicating normal operation, so the faulty Board must be the disconnected Y-Mains/Y-Buffer and at the same time I know that the X-Main is OK
I also found some original Samsung Tech-Talk bulletin which explains how to check the Y-Buffer Board by means of some Diode-Test measurements of OutL and OutH against each other and GND and there are several videos showing how to test each line buffer individually. My Y-Buffer seems to be OK, so now I can concentrate on the Y-Main to find the problem.
I will start testing the FET's and Diodes first and then have a look at the electrolytic capacitors.
Update will follow...
Yes Va rises to 55V during startup and the TV is manufactured Aug. 2010.
After more internet research I found a way to determine which board is responsible for the problem:
Disconnecting the flat cable running from Logic Board to Y-Main or X-Main is a good way to find the source of the problem!
I did it like this:
1. Disconnect the TV from the mains
2. Disconnect the X-Mains flat cable running to the Logic Board, all other cables remain in the their respective positions
3. Connect TV to the mains and switch-on
4. On my TV the error (5s/1s toggle of LED) was still present, so the faulty Board is still detected which points to the Y-Main/Y-Buffer being the problem
5. Disconnect the TV from the mains
6. Disconnect the Y-Mains flat cable running to the Logic Board, all other cables remain in the their respective positions (re-connect the X-Mains flat cable to the Logic Board)
7. Connect TV to the mains and switch-on
8. On my TV the error (5s/1s toggle of LED) did NOT SHOW UP AGAIN but instead the other LED on the Logic Board now toggles in 1s/1s timing indicating normal operation, so the faulty Board must be the disconnected Y-Mains/Y-Buffer and at the same time I know that the X-Main is OK
I also found some original Samsung Tech-Talk bulletin which explains how to check the Y-Buffer Board by means of some Diode-Test measurements of OutL and OutH against each other and GND and there are several videos showing how to test each line buffer individually. My Y-Buffer seems to be OK, so now I can concentrate on the Y-Main to find the problem.
I will start testing the FET's and Diodes first and then have a look at the electrolytic capacitors.
Update will follow...
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