LG 42" Plasma 42PJ560R - no picture

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Control board LED.

[m33x]

Re: LG 42" Plasma 42PJ560R - no picture

you have bad caps, take soldering iron if you have one and heat caps one by one, starting with 4 big caps on the middle board near to the heat sink with 8 transistors, see if tv lights up. heat caps until u almost cant put your finger on them, place the tip of soldering iron on the top metal part of the cap, ofcourse.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

it is unlikely the OP has bad capacitors, but a safer test (soldering iron may boil capacitor electrolyte) is to use a hairdryer, but I believe they tried this already.

[m33x]

Re: LG 42" Plasma 42PJ560R - no picture

hairdryer blows hot air all over the board, soldering iron heats up a specific spot, it will boil if you keep the iron for too long, logicaly, my father is an electrotehnician for over 30 years, me too with him... plasma tv starts working normaly after 30 min (?), that is a bad cap, its capacity slightly increases with temperature, after some HAPPY HOUR time of about 15 to 20 days that cap drys out or blows. my guess thats one or few of the caps closest to the heatsink.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Well, it is worth a shot, but these models aren't well known for bad capacitors. And out of probably 10 intermittent start issues, I've had maybe 2 sets with bad capacitors. Other intermittent issues can be the lead-free solder on the processors, loose connectors, cracked solder joints, intermittent MLCC... among others.

[m33x]

Re: LG 42" Plasma 42PJ560R - no picture

i agree but problems like what you listed arent common, samsung, LG, asus, all of them are same inside, same chinese shizz... caps, CCFL, inverter, mosfet are 4 most common parts that die in ANY today lcd, plasma, led screen... since plasma is 42" its really big, has more ccfl's draws way more juice, parts heat up faster, last shorter, especially caps, capxcon being one of the shizziest caps ever...

[m33x]

Re: LG 42" Plasma 42PJ560R - no picture

i used to use Nichicon caps but then customers stoped bringing their lcds for repair however i never fixed lcd over 24", never had a chance, but this sounds like an average day caps problem ... IF the plasma stays ON after ~30 min of warming up.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

A plasma does not use CCFL tubes. It uses entirely different technology.

It still uses a lot of power, but the power is mainly on Vs and Va at high voltages, minimising ripple current, unlike 24V/13V in LCD.

This LG uses mostly Samyoung caps. Samyoung are "OK" caps. They rarely go bad. There are a few Samwha, which are also "OK", nowadays... they used to be a lot poorer.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

all the caps are Sanwha except one Samyoung

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

They are probably fine. If you want to replace them afterwards, it may be a good idea to increase the longevity. I have only seen bad Samwha on older LG, this is a newer model which does not generally have issues with them.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

The small transformer is making a faint hissing sound. I have to keep my ear about an inch from it to hear it.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

Is there a way to start the tv with the control and main board disconnected?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

The 50PJ350 service manual says that, to to test the control board led, the STBY 5V from smps has to be jumped to pin 3 of IC231 of ctrl board. If the led is on, then the board is OK. But, the IC no. on my board is different - IC 121. If it's same, how to locate pin 3 ?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

What happened? No replies.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Looks like your post got missed under the pile of threads, it happens. To turn on without main board you place a jumper 100 ohm resistor between 5V Standby and M_ON, and 5V Standby and RL_ON.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

Thanks for coming back to me.
Now, regarding the jumper, I will have to use two 100 ohm resistors, right?. One between 5V stby and M_ON and the other between 5V stby and RL_ON (please see attached pic). Should this connector and all the other connectors be connected during the test? Also, what will happen after jumpering? Will the TV show any test patterns or normal display. Please explain the steps in detail, as I am afraid that if I do something wrong, I might blow something up.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

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[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

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[tw2005]

Re: LG 42" Plasma 42PJ560R - no picture

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I think the 42pj350 will line up with your model better than the 50"

Control board starts at page 82, PSU static tests start from pg 40,

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

Thank you tw2005 for the service manual. This manual perfectly matches my TV. I had been searching for the correct manual but did not find a complete one.
Many thanks again for your effort.