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I’m troubleshooting a Samsung LE32C530. I’m not the most tech savvy, so I’m having a bit of a difficulty understanding how the power supply works, the board is missing the 5V_DET signal, that seems to be the only voltage missing, where does the INV ERROR come from? I don’t know what voltage should I read here. Can I have a bad driver board even if the backlight turns on with all the cables disconnected from the mainboard? Please help me troubleshoot this problem, Thank you!
Hi @roliveir To me the 5V_Det voltage on CN802 pin 2, comes from the voltage divider circuit formed by RM 863 and RM 864 which are connected between pins 13 and 5 (Earth) on CN 803 and then goes through RM861 to get to pin 2. You would have to check that path and also the operate path for QM852 (check RM865) and also find out where pin 4 of CN803 goes to as it has input to the transistor
Hi @jayeff I was looking this the wrong way, I’m not suposed to have 5V on CN 802 pin2, that only goes high when the inverter is broken. I noticed I had a pulse voltage on PS_ON. 5V PSU on, 0V PSU off. I did the following, I removed PS_ON from CN 802, so PSU was always on, but after that I start having problems with the backlight, going on and off and randomly changing brightness. I know the inverter was working properly, so I removed BLU_ON and E-PWM from CN 802, and left it full on. I then started measuring the voltages on the output of the PSU. B5V was not stable, going from ~3 V to ~5V. B13 was stable at 12.45V and A5V was stable also at 5.12V so it had to be on that part of the circuit.
CB857 was out of spec, I replaced with a 470uf 16V (real 500uf) and that B5V was ok again and PS_ON was stable at 5.21V. TV turns on again. I connected E-PWM and left the other 2 out, I’m afraid all this constant on/off will eventually toast the inverter or the mainboard. I still have random turn off at the PS_ON on the side of the mainboard, TV crashes and comes back up again with the message on screen saying the mainboard is now and I need to go to service mode and configure it again, maybe my problem now is only configuration? I
