LG 42PJ550 continuously clicking?

[Loz2212]

Hi guys,

I've got a LG 42PJ550 that went down on me over the weekend. The symptoms are it just keeps clicking and won't start. It was intermittent for a few hours and would cycle on and off and randomly start. Now it won't start at all.

I bought a repair kit which included 2 x 22ohm resistors for R927 & R929, a voltage regulator for IC301 and a diode for D304. I'm also waiting for some SMD resistors to arrive which is another 'known fix'.

I'd like to bow to the alter of the experts here and ask your thoughts... any voltage checks I can do to narrow it down? Etc..

I hope the attached photos are OK.

Thank you.

[Loz2212]

Re: LG 42PJ550 continuously clicking?

Any suggestions?

[R_J]

Re: LG 42PJ550 continuously clicking?

You likely have a short on either the Y-sus or Z-sus boards, and not a fault with the power supply. Disconnect the plug going to the y/z boards and check what the Vs voltage is coming from the power supply.
Also you could check if you have a short or very low resistance across the Vs pins on the Ysus. also check for shorted fets on the y and z boards.
You can also use the SEARCH and look up your model to see other threads that might apply, there are a lot.

[Loz2212]

Re: LG 42PJ550 continuously clicking?

Hi R_J,

Thank you for the response - I'll check what you have suggested tonight.

I've absolutely hammered the forum over the last few days and was looking at everything power supply related... they seem to be plagued by a few specific faults on the PSU so I gravitated towards that.. I did disconnect the sus boards (only one connector comes out of the PSU for them) and the fault stayed the same. I've not measured anything yet with the multimeter but I intend to tonight.

Thank you.

[tvtimmy]

Re: LG 42PJ550 continuously clicking?

Check the 2 big white resistors on the top right side of power supply. They should read the same(10 ohms).

[Loz2212]

Re: LG 42PJ550 continuously clicking?

Hi Timmy,

I've replaced these resistors already (the attached photo was before I did the work). R927 & R929 in the top right are 22Ω. All seemed to test OK anyway but they were in a repair kit I bought so changed them out anyway.

I'll have another look tonight

Thanks

[Unspun01]

Re: LG 42PJ550 continuously clicking?

Loz2212 :

Sometimes the large copper coils on the Y-sustain and Z-sustain boards develop poor or intermittent solder joints which can cause problems, but this issue is isolated by disconnecting the boards from the power supply, so suspect power supply.

Testing power supply:

TV unplugged, capacitors discharged, SUSTAIN BOARDS DISCONNECTED from power supply:

Using TV chassis as ground, measure resistance/continuity to VA and VS pins on power supply connector with red multimeter lead. Any low resistance will highlight a possible short circuit and tell you which circuit is the issue.

TV plugged in, power button pushed, SUSTAIN BOARDS DISCONNECTED from power supply:

Using TV chassis as ground, carefully measure voltage of Va and Vs with red multimeter lead. Do you get a voltage, even momentary?

The repair kit should have two ceramic resistors, IC301, diode D304, and possibly a fuse? you did not mention replacing the fuse?

Double check orientation of installed diode D304 and IC301. Double check your installation for good soldering, and no solder bridges.