While trying to repair a PSU that uses 6105 controller I found that it was outputting higher voltages than the normal values like 16V instead of 12V all this was for a very short time then the PSU shuts itself down as a protection ( even if it was connected to a computer it wouldn't hurt it as the PG pin will stay disabled until the voltage is at the correct level and a delay has passed )
I had to disable the protection so I can have some time to investigate the rest of the signals.
the datasheet doesn't say explicitly how to do it but you can disable the Under and Over voltage protection with grounding the pins 3V 5V 12V and OPP but be aware this my leads to something bad later on. but you have to cut the traces to those pins so you don't short anything.
After that I measured the voltage at the IN input ( this controls the voltage, the reference value is 2.5V ) and found that it was 2.7 while it should be 2.5 what i think of it is that the controller internal reference voltage is bad I also tested the GND in case it is floating compared to the rest of the circuit but it was ok , so went ahead with the easiest fix and modified the voltage divider that is connected to the IN pin and that had fixed this problem but there was some caps whistling so I had to change them too.
and now that the voltages are at the normal values you can restore the protection feature for you safety .
6105 DATASHEET
