LG 42PJ350. usual 3 clicks problem

[maxvalutech]

Friends set not turning on and first thing I hear is three clicks pause three clicks. Plenty about this on forums here but like many posts often end before conclusive result recorded.
So I have downloaded the training manual dated 8/2010 for the model and note that this set from around 5/2010 has a different main board to that shown in manual. The set made in Korea may be reason why. Did manage to get the power supply working once (possibly problem is intermittent) and all voltages including Vs/Va were OK. Set turned itself off just as I finished voltage checks. While set on the control board led flashed a pattern short/short/long/short/long but no mention of codes or flash pattern in manual. Tried start with Ysus and thus X side disconnected - no go. Tried force PSU on per manual and it did turn on once but then no more - again outputs OK when on. Can't recall any sign of front led coming on at all but of course it wouldn't when main disconnected and I may have just missed it.
So it looks like PSU problem. Have checked the two top white resistors and they read OK. Will have to remove the usual suspect diode to test it as associated resistor very low ohm. It does look as if capacitor in that area is a replacement as different to all others on that board. Will probably have to buy a parts set to fix but do note they vary and in one case just a series of several smd resistors.
Any thoughts and advice appreciated as only my second LG plasma and the first is still awaiting my attention (both Y and X shorted).

[Andrew F. Ali]

Re: LG 42PJ350. usual 3 clicks problem

Not too sure what you did to 'self-test' the PSU, but you could re-try using this method.
1. Build a test lamp by connecting two (2) 120v light bulbs in series. MUST test the PSU with a load.
2. Disconnect ALL connectors on the PSU to the Main Bd., Y-sus, ETC.
3. I'm not sure about the pin Nos. on P813, but connect the STBY pin to the RL_ON pin with a 100ohm resistor.
4. Connect the STBY pin to the M_ON pin with another 100ohm resistor.
5. Connect your test lamp across the VS and GND.
6. Plug the PSU in the ac.
8. Observe if the test light came ON
9. If it comes ON and stays ON lighting bright then the PSU is GOOD. That means ALL other PSU derived voltages are present and you could double check wit DMM.
10. If the test light does not come ON then the PSU is BAD.
GOOD LUCK!!

[chrismurphy]

Re: LG 42PJ350. usual 3 clicks problem

Just fixed one of these , power board was the issue
checked all the items you did , but it did not work , finally i re-soldered all diodes and fets and then all the transformer connections and it fired up , so i suggest you just blanket the board with re-soldering especially the transformers connections and the 7 pin regulator pins

[maxvalutech]

Re: LG 42PJ350. usual 3 clicks problem

Thanks for that info chrismurphy I will give that a shot as all checks done so far for no result and I'm sure it is intermittent albeit 1 in 10+. Tomorrow my last day to work on sets before heading off for 80th birthday short 5 day cruise ship jaunt and then off out west for a few weeks.

[Andrew F. Ali]

Re: LG 42PJ350. usual 3 clicks problem

Did I read that correctly?...You are going on a 5 day cruise for your 80th birthday??

[tvtimmy]

Re: LG 42PJ350. usual 3 clicks problem

Happy birthday max!!!!!

[maxvalutech]

Re: LG 42PJ350. usual 3 clicks problem

Thanks people yes 80 on 24th. My username here came from selling/servicing laptops in hobby business 20 years ago. Had 40 years in banking, followed by 10 years house design and construction working on the tools, and 33 years among that flying light aircraft including commercially and own air charter business, but always an interest in electronics from crystal sets on. I was once told there are those who make it happen, those who watch it happen, and those who say "what happened". Make sure you keep in that first group.

[freakaftr8]

Re: LG 42PJ350. usual 3 clicks problem

That's amazing!! 80 and still got it!! My hats off to you sir! Keep strong!

[Andrew F. Ali]

Re: LG 42PJ350. usual 3 clicks problem

WOW!!....From reading posts you can't tell a person's age. Quite an achievement, Sir....When you return try my 'self-test' procedure as described in Post# 2. Good Luck and enjoy your trip.

[maxvalutech]

Re: LG 42PJ350. usual 3 clicks problem

Well after around 6 weeks away got back to this set. Also recently picked up another same model. Took PSU out of that find and it worked OK in this set so confirmed PSU as problem. Then spent an hour comparing component readings between the two PSU boards but found nothing of moment (one was review 6 this set review 8). So went over a number of joints with soldering iron plus a 10min oven bake at 200c. And it now works so have zipped the set back up and put it under test. And hey the cruise was great!!!

[Andrew F. Ali]

Re: LG 42PJ350. usual 3 clicks problem

Welcome back!!...I am glad that you were successful in determining the fault on your TV and was able to fix it. I don't trust the 'oven-baking' method, but if it works here, great. keep an eye out though for a repeat failure. Take care.

[Maxmad]

Re: LG 42PJ350. usual 3 clicks problem

In this TV, i checked everything is advised; resistors, diode etc.

The problem was one of the relays , although you can hear it clicking, no connection was made.

So i fixed the relays and now the PSU is working great testing with 2 bulbs 100w method.

So everyone has this problem should also take a look at the relays.


However, in my case the Y-SYS board have also many transistors shorted.
Still looking for fix.