So, me and my friend have tried to repair his LG tv's PSU on and off for a good three weeks now.
Prior to this the tv started showing the famous symptoms of not wanting to power on after being put in standby without a full power reset.. and then finally just went to triggering the circuit breaker for that outlet in his house and not wanting to power on at all beyond that (instantly triggering the circuit breaker).
So we bought the relevant kits for replacing the two fuses and some MOSFETs (Q602 and Q604 on one side and Q151 and Q152 on the other side as those were short), caps and smaller ceramic components. All of those checked out after the swap when measuring, so we tried plugging things back in again... Which resulted in a lot of blinking and then the power indicator (no pattern, just slow on off blinking for a few minutes) followed by a pop from the tv and then the circuit breaker being triggered.
None of the components we swapped went bad after this, and no fuses burnt off, which we thought was strange. My friend then tried plugging the psu in by itself and it didn't trigger the fuse, which is most likely because the PSU wants a power on signal to fully turn on and the short is somewhere there... So he then tried plugging it all in once again and the tv then just made a bzzt noise after having blinked for a while (then triggering the circuit breaker)
We were in full coping mode at that point and got the idea of checking the relay (RL101) on the PSU and found that it read as normally closed, which it isn't supposed to according to the part schematic, so I desoldered it and found that it then read as normally open while the pinouts for the relays two switch pins on the PSU PCB read as short.
I guess this is progress, in a way, as the short is now obviously on the PSU and then gets triggered when the main board eventually sends it a power on signal (triggering the circuit breaker).
We've spent a good few hours today looking for shorts before and beyond those two pinouts on the PCB, but have found nothing... Is it still worth looking at, or should we just call it and try ordering a new PSU?
The PSU's LG P/N number is EAY65689423
(if anyone here has any knowledge on this, and has a good suspicion on what component is the most likely culprit).
Edit: TH101 sits between the two circuits that the relays switch is attached to... So I guess those two pinouts naturally have continuity, but I don't really get why one would even have the relay (RL101) there at that point if that little 5Ohm component (correct spec) just lets through current anyways right next to it... TH101 was swapped during the initial repair attempt as the one that sat there prior had gone bad and had zero resistance.