Chosen Solution
Hi My LG 42” TV has developed a fault. The standby LED is lit but when the TV is turned on either by the switch on the TV or by the remote the LED blinks twice then goes out, nothing is seen on the screen and no sound it heard. I thought this must be a classic case of PSU failure so I took a look at the board. I went straight for the capacitors looking for bulges or leaks but they all looked OK so I measured the output voltages going to the main AV board.
The output voltage values can be seen in the photo above, the readings I obtained are as follows: GND - GND 12v - 12.07v 12v - 12.07v GND - GND 24v - 22.9v GND - GND 3.5v - 3.4v 3.5v - 3.4v As can be seen the 24v rail is slightly down, could this be the cause of the TV not turning on? Just to try something else I obtained a known good replacement AV board and swapped it for the one installed but the problem is still the same. This is the PSU board, can anyone tell me if I should be looking for anything else other than the capacitors (I have replaced a couple that are marked but it did not change the voltage readings) should I test all of them? as this would mean removing them from the board as I cant test them in circuit. If the problem is in the PSU board is the primary or secondary side be the most likely. This is the PSU board:
Any further insights into this problem would be welcomed. thanks.
It seems the PSU is ok, but if not it would be in the secondary side. Find the service manual, the 2 blinks are probably a diagnostic code. It may apply to many models from same mfgr. You’ll need the manual to dig further anyway. Good pict: I’m seeing 2-3 switched mode sections and ~10 capacitors any one (or more) of which may be the issue.
