LG plasma 50pk550 EAY60968801

[aaronwt6]

Re: LG plasma 50pk550 EAY60968801

Dear all, finally I found the culprit of cycling relay. I have checked and change all the high esr elcap and still clicking. I found that there is a bad joint in the T901 transformer. After resoldering the joints its back to live

I know this is a really old thread but thanks hartonoh for this post. Everything discussed her previously checked out on a power supply I have here and this put me in the right direction. I'd already inspected for cracked joints and overlooked one on one loan leg for T901.

[hartonoh]

Re: LG plasma 50pk550 EAY60968801

Dear all, finally I found the culprit of cycling relay. I have checked and change all the high esr elcap and still clicking. I found that there is a bad joint in the T901 transformer. After resoldering the joints its back to live

[tw2005]

Re: LG plasma 50pk550 EAY60968801

sorted itself out after a few power cycle. Been booting up and working perfectly.

Whats the service menu button combo? I'd like to check the hours. It's very very nice, could be low hours.

tw2005: I owe you at least a few fosters for your help j/k, Ill get you some real beer!

Fosters? I can feel a XXXX coming on,

https://www.youtube.com/watch?v=RMRy8bjdohs

https://www.youtube.com/watch?v=GniEAoEHG_c

https://www.youtube.com/watch?v=PcDuU-C5I0w

https://www.youtube.com/watch?v=vAB0SGh6q18

https://www.youtube.com/watch?v=0yM9xD6RQj8

[veikra]

Re: LG plasma 50pk550 EAY60968801

sorted itself out after a few power cycle. Been booting up and working perfectly.

Whats the service menu button combo? I'd like to check the hours. It's very very nice, could be low hours.

tw2005: I owe you at least a few fosters for your help j/k, Ill get you some real beer!

[veikra]

Re: LG plasma 50pk550 EAY60968801

I replaced zd301 and it solved the rapid clicking.

Now I get the normal slow click and retry. click click red light dims slowly as it shut off both relays. The normal problem you know.

EXCEPT : I THINK this is mainboard related. Why? Because I can instantly start the tv if I probe the 5.1 rail at the mainboard connector relative to chassis ground.

I bet I could put a 10Meg resistor and it would work flawlessly

Something to think about

[veikra]

Re: LG plasma 50pk550 EAY60968801

Ordered new diodes, will post results tuesday or wednesday when I get them

[tw2005]

Re: LG plasma 50pk550 EAY60968801

You forced it on and all of sudden tv works fine? if so weird indeed i had a samsung 21' monitor do something similar except when i replaced caps on it and a pair of fets it wouldn't work so while it was plugged in and turned on i started to wiggle components caps, and connectors and no go...... so more wiggling then on inverter i wiggled a cap all of sudden it made a spark arc sound and it worked flawlessly ever since. just little touch up on the joint and all was well even though the joint looked ok. weird

Yeah, hard to trust this POS. Great picture though plus this one has had the mainboard replaced with a measly 260 hrs so with a new PSU could get 5-7 years from it

[tw2005]

Re: LG plasma 50pk550 EAY60968801

ZD301 seems shorted in circuit, Ill pull it and check whenever I get time tonight

Have the part number handy?

It's a 30V zener. I've used 1N4751 which is likely a higher wattage. Got several because it seems easily spiked when I poke around one of the optos.

[veikra]

Re: LG plasma 50pk550 EAY60968801

ZD301 seems shorted in circuit, Ill pull it and check whenever I get time tonight

Have the part number handy?

[heavymachines]

Re: LG plasma 50pk550 EAY60968801

You forced it on and all of sudden tv works fine? if so weird indeed i had a samsung 21' monitor do something similar except when i replaced caps on it and a pair of fets it wouldn't work so while it was plugged in and turned on i started to wiggle components caps, and connectors and no go...... so more wiggling then on inverter i wiggled a cap all of sudden it made a spark arc sound and it worked flawlessly ever since. just little touch up on the joint and all was well even though the joint looked ok. weird

[tw2005]

Re: LG plasma 50pk550 EAY60968801

Still wasting my life on this one but I've forced everything on at P813, end result is the same as in the TV except instead of quitting after 3 powerup cycles, it continues so the mainboard must quit powering up , 3 strikes, you're out.

it has

Stdby 3.4 - 5v on run

M17V is present, M5V is on, Err Det (not used) is 4.9V, AC DET is also Ok 4.9V

VA, VS zippity do dah

I've swapped L6599D, R2A02117 and the micro all from a good board , no change

I've managed to spike and kill ZD301 several times now probing the optos, that kils the 17V around IC301 and rapid endless cliking.

I've confirmed the micro off the bad board is ok as the good board runs just fine using it.

Oh and the 60" is running fine, no idea but ever since I jumpered that one and forced it on, it's been fine, WTF, bad caps?

[tw2005]

Re: LG plasma 50pk550 EAY60968801

When you get rapid clicking, check zd301 for short, 17V will also be missing. Sits around ic301.

[tw2005]

Re: LG plasma 50pk550 EAY60968801

No change but just got my 60" going, EAY60968901.

LOL, Maybe not

[tw2005]

Re: LG plasma 50pk550 EAY60968801

No change but just got my 60" going, EAY60968901.

[tw2005]

Re: LG plasma 50pk550 EAY60968801

im concentrating on the microchip. It's not getting feedback from the first relay clicking on. Did you download the schematics I linked?

Yeah , that's by paulstef. generally I take good guesses but this has been tough. Not a great fan of powering it up and probing. I have a tendancy to get the jitters and short stuff.

It also appears the micro is programmed too.

[veikra]

Re: LG plasma 50pk550 EAY60968801

im concentrating on the microchip. It's not getting feedback from the first relay clicking on. Did you download the schematics I linked?

[tw2005]

Re: LG plasma 50pk550 EAY60968801

my this could be the optos ! I had some weird mesures with them but shrugged it off when remesured them correctly later... Definitely something Ill try and scavenge on other boards.

the 3 cycles then stop was my previous problem, and was a bad infineon 3br chip not booting right. I have bought many, and the first I replaced was a dud. Can't find them on digikey, only on shady ebay sellers.

I have a bunch of good working ones .

Pretty sure the #br chip I have is in fact one out of a working board, could try swapping back I guess. I generally don't touch power supplies and without proper fault finding I am shooting in the dark,

[veikra]

Re: LG plasma 50pk550 EAY60968801

my this could be the optos ! I had some weird mesures with them but shrugged it off when remesured them correctly later... Definitely something Ill try and scavenge on other boards.

the 3 cycles then stop was my previous problem, and was a bad infineon 3br chip not booting right. I have bought many, and the first I replaced was a dud. Can't find them on digikey, only on shady ebay sellers.

I have a bunch of good working ones .

[tw2005]

Re: LG plasma 50pk550 EAY60968801

Not sure what happened but I remembered I swapped 2 FETS from another which were 3Amps less. put the 15A ones back in brushed up a couple of spots and a clean. Farking thing, back to clicking but only does 3 or cycles then quits.

Over it TBH.

Tried reversing back to where it was working, nup. Stuff it.

[tw2005]

Re: LG plasma 50pk550 EAY60968801

Just got another one of these, my be closer to the issue you.

So this one. stdby 3.4V ,but at RUN= 5.1 v . 17v was present, no Va or Vs
Relays just clicking.

Resistors good, check all solders and reflowed. Nothing shorted,

Swapped out all main Ic's from good board, - no change

Started swapping optos, no change..................until I changed PC101,102. Can't say which one but now it's running.

Funny thing I started with an opto swap , just the wrong one based on a mention somewhere in another thread.

They're nothing special real common garden variety opto you see a lot. chances are if you have some boards laying around you'll have something