LG-50PQ6000 clicks and clicks and clicks

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Back to the drawing board. Put the PSU back in the TV today and same old symptoms. Just looks like the TV wont fire up and keeps clicking and trying.

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

Does AC-DET still give a varying voltage?

[popal]

Re: LG-50PQ6000 clicks and clicks and clicks

could u please tell me what is the value of cap c360 and c351 on power splly board.

[YellowJacket]

Re: LG-50PQ6000 clicks and clicks and clicks

Hi friends,
I would open this topic, since there is literally no info about this TV and I have exactly the same issue. I am unable to find any power board schematic, so it is really hard to troubleshoot it.
Before I found this topic, I tried to reverse engineered some connection ( attached, little chaotic for others, but I can explain more if needed ) and went to conclusion, there is something wrong exactly with these two optocouplers, which were mentioned here. But as Baileybum said, shorting its outputs didn't help neither me. Then I found this topic and I realized, it has to be common fault in this TV.
In short about this power board:
- board is out of TV and tested alone, without anything else connected. There is no relay clicking at all.
- there is programmable IC IC701 MC80F07086, which drives Q351 ( via Q361 ) to generate STBY_5V, from 5V going from T301. STBY_5V is fluctuating ( attached ), but 5V is nice and stable. So IC701 is from some reason restarting STBY_5V.
- PC102 is detecting AC ( before relays obviously ) and I have 0.9V voltage drop across LED inside optocoupler ( in datasheet is mentioned Vf=1.2V ), and there is some fluctuating voltage on its transistor side. When I short it, I got realay click once, got voltage on main capacitors C351, C360; STBY_5V is stable now and then immediately click again, shutting them off.
- PC103 is driven by IC701 and it is telling hot side to start PFC ( IC601 gets its VCC voltage )
- PC101 is detecting if this PFC voltage is correct ( in my schematic, it is not finished, but there is another resistor series, ending with R115 and starting at D308 anode, marked as PFC ). When I shorted it along with PC102, nothing happened. Relays started and then immediately turned off again. If I put board into TV, it behaved exactly the same.

I was thinking, there must be issue somewhere around here, and I am just walking in circles around it. But when I faked those optocouplers and force them to act like there are right voltage values, and then when I read here, it didn't worked even for someone else, I am really lost.
So I would like to ask you guys, if there is some schematic available after few years, or if not, if you have any ideas, what can I check. Big thanks in advance.

[YellowJacket]

Re: LG-50PQ6000 clicks and clicks and clicks

OK guys, it took me few days, and lot of reversing for nothing. The issue was really easy to find even for beginner - blown rectifier diode for 12V power lane ( from T301, together with 5V lane ). But I didn't measure any diode before, only transistors and double diodes mounted on heatsink.
If anyone in future has this issue with this TV model, I believe, it will be same issue. The diode is D352.

[Ahmedashik]

Re: LG-50PQ6000 clicks and clicks and clicks

OK guys, it took me few days, and lot of reversing for nothing. The issue was really easy to find even for beginner - blown rectifier diode for 12V power lane ( from T301, together with 5V lane ). But I didn't measure any diode before, only transistors and double diodes mounted on heatsink.
If anyone in future has this issue with this TV model, I believe, it will be same issue. The diode is D352.

Thank you YellowJacket for the findings. I have a LG Plasma TV 50PQ30 model. No picture/ sound, the standby light comes on, flickers (not blinking) and relay starts clicking few times and the system goes off including the standby light. Voltage across the fuses and ground fluctuates to 200-360v range.

I had changed all capacitors and voltage rectifier diode (STR6252), nothing worked. I followed Yellowjacket's suggestion and found the diode shorted. Replaced VSB5200 diode woth SF36 since i couldn't find the exact diode and it works. Have been trying to fix it for more than a week now. Thanks for taking the time to post your finding. Many OPs don't post the solution or their findings, many forums I read had no updates from the OP. It was annoying after reading so many pages of posts and you find no updates from the OP.

The TV works perfectly for now except a yellow thin (single) vertical line across the screen. It disappears on black/ darker images and shows up on brighter images. Any fix?

[Ahmedashik]

Re: LG-50PQ6000 clicks and clicks and clicks

The original diode was a VSB3200 and replaced with SF36