Samsung SyncMaster 710mp TV/Video fine, but on VGA goes dark

[sharkie8080]

Re: Samsung SyncMaster 710mp TV/Video fine, but on VGA goes dark

Thanks for the wisdom guys..
ive got a 710MP S that had blown caps on the power supply side ive replaced what appeared bad but still no power. having read the forum will replace all caps and try again, but would the mosfets also need replacing Thanks in advance

[drgst]

Re: Samsung SyncMaster 710mp TV/Video fine, but on VGA goes dark

Hello everybody! This is my first post so forgive me if i miss something to explain.

I have this same TV that suddenly died on me. I had to replace all of the caps in the power supply and one resistor in the feedback circuit between the two legs of the optocoupler (pins 3 and 4) to be able to get the proper 5V and 14V from the IP board. Additionally I had to replace IC103 G960T45R (3.3V Voltage regulator) from the mainboard, before I get some kind of signs of life from this TV). Now I have it working in PC mode, but still not in TV Mode. When I'm cycling through the TV options in the main menu they look grayed out and when trying to select them the message "not available" appears. The PC mode options all appear fine and respond well. I measured the voltage from all of the voltage regulators on the mainboard and all voltages appear all right: 2.5V, 3.3V, 5V, 8V are all there. I still haven't replaced any cap on the mainboard but I don't think that this could be the cause for the TV mode not working, because the voltages are fine. One problem I noticed only is that the 33V for the tuner is down to 4V, but I think that this could only be a problem for finding channels and not for the TV mode not working at all. The other 5V for the tuner is all right. I measured the pin on the tuner that receives the 33V for resistance and saw Mega Ohm resistance. I disconnected the pin from the tuner and received around 32V from the circuit.

I fear that the problem could be due to some processor on the mainboard or maybe the tuner. Has anyone else experienced something like this, or has any idea what could be the problem?

I have attached the schematic of the mainboard.

Thanks in advance for your help.