Lg 42" plasma model p2pc3d-ud

[muskin]

Hi I just picked up a LG 42" PLASMA MODEL P2PC3D-UD. When I power the tv on it flashed 3 green lights then goes to red.
This is what I have tried so far:

I checked the fuses on the sustain boards.
I found one bad fuse on the z-sustain board.

From posts I have read I should be able to disconnect the z-sus and the tv should power on but with no picture. This does not happen.

I have tried disconnecting the y-sus and then plugging back in the cord and powering the tv on. I still get a green light that then goes to red.

I checked the fuse on the power board and it reads .3 at 200 ohms. So I think this fuse is good.

What is the next step I need to do? I checked all the caps and do not see any domed shaped or oozing caps. Could the power board have taking out the z-sus board or would a bad z-sus board be able to kill the power board?

Any help will be greatly appreciated.

Here are the numbers on the power board:

LGE:6709900019A
PCB:68709M0031A/5

Z-SUS BOARD:

6871QZH956A
PD42067K071960

Barry

[PlainBill]

Re: Lg 42" plasma model p2pc3d-ud

One slight problem - unless LG did something very unusual, the model number is 42PC3D-UD. This model is notorious for failures of the hybrid in the Y and Z sustain. It also notorious for a very poor design making replacement of the hybrid unnecessarily difficult.

The fact that the fuse was blown in the Z-sustain indicates the Z-sustain is bad, likely cause the afore mentioned hybrid. It is unusual that the TV will not power up after the fuse was blown.

First step is to disconnect the power cables that go to the Y-Sustain, the Z-Sustain, and the X-buffers. If the TV still fails to stay powered up, start checking every output voltage on the power supply. If they are good, suspect a problem with the main board.

Given the multiple failures, consider the possibility that this was the victim of a power surge.

PlainBill

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Thanks PlainBill you are correct about the model number. I will check all the things you said to check and will get back with you.
Thanks for the quick reply.

Barry

[slappala]

Re: Lg 42" plasma model p2pc3d-ud

Yes, I would start checking the voltages on the powerboard, BUT be carefull!!!!

Also I have been tackling few days with LG 42PC3RA (Same as 42X3?? and maybe some other models depending on the country)
I found that the thermal/resistor near by the Zsus board connector had given up. Probably due to the fact I have CAPs problem on the power board and the tv is really hard to start. Starts to click on/off/on/off..still waiting for the Panasonic caps from farnell.

I also Added old intel PC fan from the empty 5.v connector to Y-board sink and tweaked all Va and Vs lines to minimum level. I could not see any really bad contrast difference so I will keep them at really low levels to save some old electronics and imp:s. what#s left of them. Also doign this the picture is better and no more red pixels.

Luckily mine was only half dead when bought..Hope it will last longer with these tweaks..

So some hint's if you get it going..

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Well after a long night at work, I got a chance to look at the TV before I went to bed. This is what I found this morning.

I checked all the output voltages on the power supply board. They all checked out ok.
I unplugged all the connectors. Y-Sustain, the Z-Sustain, and the X-buffers. TV comes on now with all the connectors unplugged. I hook up the Z-sustain and turn the TV back on and it stays on.[but this is with the bad fuse in it, when I put a good fuse in it the TV shuts off, so I can conclude that the Z-sustain board is bad] I next unplug the z-sustain board and hook up the y-sustain board and turn the tv back on and it goes off. [ at this time i have the buffer board attached to the y-sustain, so I unhook the buffers just to rule out them. The tv shuts down again with the buffers disconnect from the y-sustain board. So from this test, I can conclude that both the y and z sustain boards are bad? Correct?]

[PlainBill]

Re: Lg 42" plasma model p2pc3d-ud

Well after a long night at work, I got a chance to look at the TV before I went to bed. This is what I found this morning.

I checked all the output voltages on the power supply board. They all checked out ok.
I unplugged all the connectors. Y-Sustain, the Z-Sustain, and the X-buffers. TV comes on now with all the connectors unplugged. I hook up the Z-sustain and turn the TV back on and it stays on.[but this is with the bad fuse in it, when I put a good fuse in it the TV shuts off, so I can conclude that the Z-sustain board is bad] I next unplug the z-sustain board and hook up the y-sustain board and turn the tv back on and it goes off. [ at this time i have the buffer board attached to the y-sustain, so I unhook the buffers just to rule out them. The tv shuts down again with the buffers disconnect from the y-sustain board. So from this test, I can conclude that both the y and z sustain boards are bad? Correct?]

Probably. There has been at least one case where the problem was a bad Z-Sustain and a bad power supply. I would suggest you replace the Z-sustain (They go for $50 on eBay; a new hybrid will cost about $40). If the power supply (TV) still shuts down, check what voltages / signals are missing ad causing it to shut down.

PlainBill

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

PlainBill I rechecked the outputs on the power supply board again. I did noticed that on the 3 pluggin that goes to the main board, the middle connectors it calls for 3.3v on two pins, I was getting 0 on both of these.The connector to the right of the middle was calling for 3.3V also and I am getting 0 on it. Good call on the power supply. I will get my electrical friend to help me trace back to where I'm losing the 3.3volts.
I should have paided better attention to the reading before I went to bed after working 12 hours.
Thanks for the quick responses.

Barry

[slappala]

Re: Lg 42" plasma model p2pc3d-ud

Power supply problem can show also as a y/zsus board problem. Take your time to check it.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Thanks slappala.. I will be getting off work in an hour. I will recheck everything again. [always good to double and sometimes triple check everything.]

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Hum just rechecked the output voltages and they are all off now. I guess I will do a simple power supply swap and go from there.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Welll I switched out the power board and the z-sustain board. TV comes on and has a picture. PlainBill from the manual I have for the tv it says to hook the positive to p805 and the negative to p805 to adjust the va . then the same for the vs? From the attached picture can you tell where this might be located. I have a P811 and P812 but no p805.

[slappala]

Re: Lg 42" plasma model p2pc3d-ud

Just connect the multimeter between Gnd- and VS+ for higher voltage, adjustment from vs pot and Gnd + Va for the lower voltage. Adjustment from Va pot.
In my TV the right adjustment values for the plasma panel were on sticker back side of the panel, upper left corner.

My PCB:s have all markings silk screened/marked beside the connectors.

Nice that you got it going! I'm still trying to avoid bying new boards and repair what I can on old ones..we'll see.. :/

Also on my powersupply shares the Va and Vs traces right after the connectors so it's just the same wich connector you use for measurement. Be carefull..connect the voltage meter leads ready before main power cord is connected and use isolated screwdriver for pots just in case you slip it

that Vs line for sure will kill you or give your heart some extra beats if accidently touch it..

PS: The power supply should have voltage pots for 5.v Vs Vs lines. 3.4.v line pot has some glue on it. But since you have new board I guess that is a little late. Have not seen pots for 19.v, 12.v or 6.v on my board.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Ok I found the P805 and it is on the mainboard. Is this the correct P805? I have attached another picture of the mainboard with P805 on it. I suspect the far right is the ground and the other two are va and vs.

Thanks
Barry

Sorry for all the noob questions but I hope to get it right the first time without frying it after fixing it.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

slappala I have a spare Y-sustain board if you find that yours is bad.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Ok just checked va and vs... sticker calls for 186 and 60. I am getting 185.5 and 59.9. Looks like I can button her back up.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

I notice some very small red flashes very tiny. I read I could adjust the va or vs slightly to remove these?

[slappala]

Re: Lg 42" plasma model p2pc3d-ud

I notice some very small red flashes very tiny. I read I could adjust the va or vs slightly to remove these?

Good to know about the ysus board.

We'll I'm doing my first tv repair too , just been reading a lot and trying to figure it out.

I adjusted the voltages to minimum for now.175.5v and 54v

Got still some sparks occasionally when was watching, but mainly gone. Maybe they will lessen in time and I can take voltages up some. No idea if the screen will get affected off this, but electronics run a lot cooler+I did not see too much difference in picture.

Also the menu adjustments affected this red dot symptom.

Maybe I will try to get to it more if repair is successfull.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Hum I was wondering if I can update the firmware on the board. Has anyone done this with this TV?

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

Thanks slappala for the help. I notice on the firmware update it too had dropped the voltage. I will try just dropping the voltage on the va and vs to see if this helps the red sparkles.

[muskin]

Re: Lg 42" plasma model p2pc3d-ud

I found a pretty good pdf about this board, Slappala it might help you on yours too?