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Equipment Repairs => PLASMA TV forum => Topic started by: Baileybum1234 on September 17, 2012,16:34:55

Title: LG-50PQ6000 clicks and clicks and clicks
Post by: Baileybum1234 on September 17, 2012,16:34:55: Hi guys,

Im new to this forum.

Just to explain my background. Im an audio visual engineer and have an electrical background.

BUT (and a big but) I dont have mutch experience with the inner sides of plasma screens.

I was sent to site to swap out a faulty screen and asked the customer if they wanted me to skip the old unit. Well lets just say I saw this as an opportunity to bag myself a decent TV and learn something about the inside guts at the same time.

The fault seams common it doesnt come out of standby just clicks and clicks and clicks.

I have had a good look inside and all the capasitors on the PSU board look fine. I have ran a DVM across the pins and all voltages appear to go high and then low with the clicking.

Seams to be a tiny relay clicking.

I have removed the PSU board and plugged it in and the same is happening. I dont know if this was a test or not.

It could be a number of things I just need a little prod in the right direction to fault find it a little further.

Thanks in advance for any help!

Jarrett
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: jordan on September 18, 2012,02:05:08: If plug P-813 for SSB from PSU is disconnected then all the rails are OK (VA,VS,17V)-replace SSB board
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: tv tony on September 18, 2012,02:17:59: But the poster has intimated that the psu does not free run, these normally do, i'd check carefully around the 5v supply for high esr caps
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: Baileybum1234 on September 18, 2012,14:07:54: Quote from: tv tony on September 18, 2012,02:17:59
But the poster has intimated that the psu does not free run, these normally do, i'd check carefully around the 5v supply for high esr caps

Hi TV Tony you understood right the board doed not free run for example the AC detect pin is 5v then 0v in time with the clicks of the relays (maybe 1 second high then one second low ect ect ect). Just to confirm this is the PSU board is 230v powered up on its own with no other boards plugged into it from the TV.

Please could you give me a pointer into how I can identify the 5v supply part? I dont have a circuit diagram and learning here. Do I need to give a good visual inspection of the caps and maybe desoldier them and test?

Thanks for the help guys mutch appreciated.

Jarrett
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: tv tony on September 19, 2012,05:36:41: hello, we are account holders with lg but at the moment we have lost the tech web site, is the standby 5v constant? in any event the circuit for the psu wont be included
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: Baileybum1234 on September 19, 2012,14:20:21: The standby 5v is not constant it fluctuates down to about 4.6-4.8 when the relay randomly clicks about every second or so.

Jarrett
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: Baileybum1234 on September 20, 2012,14:45:45: Any one know how to test the AC-DET optoisolators. Had a tip off it could be this??

Jarrett
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: Baileybum1234 on February 17, 2013,05:01:05: Well I fixed this fault by replacing a Schottky diode that was shorted. It worked for a about 6 weeks and went again with a different fault. Typical. My SB5v is now 4.45v and I really dont know why?? :41:
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: marky mark on February 26, 2013,17:07:19: Perhaps the board is going into protection mode?
Title: Re: LG-50PQ6000 clicks and clicks and clicks
Post by: Baileybum1234 on February 28, 2013,06:11:43: Quote from: marky mark on February 26, 2013,17:07:19
Perhaps the board is going into protection mode?

Hi Mark its definately something to do with the protection mode I think. Its just finding out what.