Samsung Syncmaster 931BW - No Power

[aliens]

Re: Samsung Syncmaster 931BW - No Power

Those voltages are some common voltages we see.
One thing to think about the flow chart you're looking at is for no power, you actually have power.
The front power LED is not turning on and 0 volts on the Back light on pin indicates that the logic board is not asking for back lights to be on.
One other simple test would be to verify that on/off pin on the front panel switch changes state as the power button is pushed. Usually this starts out as a high voltage and goes low when the power button is pushed.

I can confirm that. The button is connected to 1.8V, which goes to 0V when I press the button (but pin 9 doesn't change from it's value of 0.141V, so it still doesn't seem to request back lights).

[aliens]

Re: Samsung Syncmaster 931BW - No Power

Could the problem be one of the other caps I haven't replaced? They look ok but I guess that can still be misleading.

[alexanna]

Re: Samsung Syncmaster 931BW - No Power

If it's a cap it would have to be on the logic board.From what i can tell the power supply is working correctly.
I don't know if this the correct name for it but,I would suspect a problem with the the user eprom on the logic board.
Someone else will have to answer if it is serviceable or not.

[aliens]

Re: Samsung Syncmaster 931BW - No Power

2 more thing I tried.

1. I went to the troubleshooting no video step (analogical one) and skipped the tests required an oscilloscope to the step checking the voltage on CN400 (the connector that goes from the logic board to the LCD), and there was no 5V on pin 1,2 and 3. Following that I tested the PANEL_EN and BL_EN signal (they should High and Low for ON), and both of them were Low (the PANEL_EN one was 0.6V).

I also tried testing the digital troubleshooting part, since it revers to the same 1,2,3 pins for 5V, but couldn't find the resistances they claim.


2. The computer seems to recognize the monitor though. I don't have a second monitor to test, but I unplugged the signal cable while the monitor was plugged in, and I got that windows sound of disconnected device. When I plugged the signal cable back in the reconnected device sound played.


Any suggestions where I can go from here?