LG EAY60968801 Power Supply Unit(Plasma 50pk series)

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

Keep up, so to recap PFC good at 390v but no VS have you changed the L6599A control chip ,what are you seeing on the outputs of Q801/802 primary side of VS transformer ?

L6599A has been swapped out several times and also has been confirmed good placing it into the working board and no fault,

So on the drain there's 198-200V there that's to cold gnd. Gate goes to 0, Source reads same as gate. There's a resistor between the G - S and when the relays relax it shows about 1.5v and tapers down

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

Normal board around 45V where I have zip. On L6599A when i was pokinh arond I think RFMIN is close to 2v when running. Nothing on the bad.

[flocko]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

you need to use hot ground (neg leg of main cap)the two primary side tapping on the transformer are in series what are you seeing across the them( you may need to check and compare with the good board ).

[flocko]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

keep tripping over each other glad to see your on the ball,I think you have changed PC901 that will also stop the controller bringing up VS

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

So for this continuing education. PFC can sub for 200v and 0.4 for th eother. Working 90-95V and PFC.

As for the transformer I don't know what point but the same voltage as the transistor since it's switching the transformer.

Yes PC901 has been swapped and I think that may be the one I spiked and took out the zener

very reluctant to play with the new board now though seeing I'v replicated the fault onto a working (was) HD board

[flocko]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

PFC can sub for 200v and 0.4 for th eother. Working 90-95V and PFC.Sorry you have lost me there? so where has the 390V PFC gone ? keep going you will get there but without me tonight , I am off to bed keep me updated good luck

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

PFC can sub for 200v and 0.4 for th eother. Working 90-95V and PFC.Sorry you have lost me there? so where has the 390V PFC gone ? keep going you will get there but without me tonight , I am off to bed keep me updated good luck

Sorry, I had to dive out suddenly. Right you said to change the gnd point which will change the values but in this situation somewhat academic. So PFC 390 is now measured ath e ths ame point as 200v and 0.4 in place of the 1,5v.

No I won't find it this is my 4th straight wekend and every other spare moment I feel that I've put into it.

[flocko]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

ok back for a short time, we are going round and round here, and i am getting giddy,so lets start again. Power board jump auto ground to ground standby should read 3.5v, make RL_ON high, relay should come in,stby should now go to 5v ,17v, AC DET 4-5v,PFC (read at F302/801) 390v.make M_ON high to give VS/VA.at what point does the board fail?my thoughts were at the M_ON stage but you seem to be having a problem with the PFC ?

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

ok back for a short time, we are going round and round here, and i am getting giddy,so lets start again. Power board jump auto ground to ground standby should read 3.5v, make RL_ON high, relay should come in,stby should now go to 5v ,17v, AC DET 4-5v,PFC (read at F302/801) 390v.make M_ON high to give VS/VA.at what point does the board fail?my thoughts were at the M_ON stage but you seem to be having a problem with the PFC ?

well it simply does not produce Va or VS. Va Vs and M5V all come on together with M_on going high.

M5V is good, zip on the other 2 and yes all other levels are correct. When the micro conroller fails to see Vs it retriggers the relays,

On a separate note I'm on a 42PJ650 with a EAY60912401. all these boards are essentially simlar designs, components etc of this period.

This one briefly flashed the panel. Fluked it on and left it running, turn off over night and same problem, 3 cycles and quits, difference being it is actually producing Vs and Va. Found the level had been knobbled at 190v.

anyway, after reflowing joints, rebuilding the resistor netwrok that feeds the micro processor, Mr Heat was applied.

Eventually she fired up once I hit the Zsus area.

Culprit was a dud 330uf 25V on ZSUS, changesd and now reliably turns on.

Tricky sets to work on.

Now thinking maybe, bad caps on the PSU is a possibility and this thread seems to indicate some similarities and fix doing the caps.

https://www.badcaps.net/forum/showth...0912401&page=3

[flocko]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

Replacing caps would be my first call on any failing power supply, second to dry joints? thought you would have that covered after four weeks, your slipping TW this is schoolboy stuff

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

Replacing caps would be my first call on any failing power supply, second to dry joints? thought you would have that covered after four weeks, your slipping TW this is schoolboy stuff

Very much doubt a schoolboy could fix this. Yes I may need re-training. generally don't need to do capwork, in fact very rare maybe because I don't work on this rubbish but hard times and very little Panasonic stock as every man who has internet access is fixing TVs.

back to the power board.

[flocko]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

Yes I have to say this forum and youtube has had a hand in putting a lot of old time Tv repairmen out of a job.If you keep putting wood on the fire sooner or later you are going to run out of wood.so I see it as rough justice, if you get my drift Flocko

[tvsteve2]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

I have pulled my hair out on 3 of these then I got a tip to resolder the big transformers the top one was the problem and I couldn't see bad solder but a good hot resolder fixed all 3 I hope that's your problem

[tw2005]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

I have pulled my hair out on 3 of these then I got a tip to resolder the big transformers the top one was the problem and I couldn't see bad solder but a good hot resolder fixed all 3 I hope that's your problem

Thank, I think I've tried tahst, they are really bad in the quality department. Out of location so it can lay. I've put the one and only good board back in a TV to sell, ready to quit on it. i would rather learn something from it though

[jalajjain]

Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

Great discussion from all experts
I have LG 50Pw450. When i tuen on two clicks of relay heard back to back and then TV shuts off. I measured STNDBY on power board and it is 5.2V. No other voltage on any pin
Any suggestions