LG plasma 50pk550 EAY60968801

[veikra]

hi,

I have a trouble finding the problem with the eay60968801 power supply. Problem is confirmed being from the power supply as I have fixed it before but now it's a different problem.

First repair: IC301 3br1565 infineon chip. worked for a few days, then wouldnt start again. Everytime Id pop a new IC301 in it it would start then eventually stopped

then it wouldnt come back on, acted just like the first time. clickon on then off and red led slowly dim. Then it retries.

BUT I took it hook to bench test it, and now it has a different clicking. Now only 1 repair clicks, and it's a more rapid clicking. click click pause click click but all on the same relay. the second relay beside it doesnt click at all.
the 164V point near ic301 drops when the relay clicks on, and standby plummets

I have replaced these so far :
IC701,IC301,IC601,IC801
D602,D603,D304
Q601,Q602,Q801,Q802
R927,R929,R607,R613,R934,R305
fuses are good,

I previously saw a post where someone had drawn up the schematics, but didnt find them this time.

I could use some help <.<

[freakaftr8]

Re: LG plasma 50pk550 EAY60968801

What is your voltage across main caps on primary side of supply? Sounds like a low voltage feedback circuit problem.

[veikra]

Re: LG plasma 50pk550 EAY60968801

130v to 160V across the 3 big caps that are laying down on the primary side

[freakaftr8]

Re: LG plasma 50pk550 EAY60968801

Ok how hot is it regulator getting as the TV was running? Also what is your voltage to the VCC pin on that Infineon regulator?

Also pin 8 on output to mainboard is Error detect. Getting any voltage there? In standby voltage should be 2.85v and in operation should be more like 4v

[veikra]

Re: LG plasma 50pk550 EAY60968801

the 3BR chip doesnt heat up .

And considering the vcc of it varies from 3 to 9V in time with Rl 101 clicking...I dont think it's booting up at all.

BUT we may be in the right direction, the D303 diode is warming up 5C over ambient, and in circuit mesure a dead short circuit.

I'll take it out and check it

[veikra]

Re: LG plasma 50pk550 EAY60968801

diode D303 is good out of circuit, so something connected to it is shorted

[veikra]

Re: LG plasma 50pk550 EAY60968801

Also pin 8 on output to mainboard is Error detect. Getting any voltage there? In standby voltage should be 2.85v and in operation should be more like 4v

sorry missed that last part. Pin 8 on the header, error detect is 0V.

I have neither a standby or on, it's constantly switching on and off.

Anyone has IC701 datasheet?

[veikra]

Re: LG plasma 50pk550 EAY60968801

The transformer's coil connected to D303 is 0.4ohm , hence why I thought I had a short. Disconnecting it doesnt change anything

[veikra]

Re: LG plasma 50pk550 EAY60968801

3BR1065 chip supply is now 12-15vdc between VCC and GROUND
It should be able to boot, but no 164V at F302 still.

I knocked off and lost c101 near ic701. But it seems related to in-circuit programming so I dont think it's my issue. I put a random salvage on.

I started drawing the schematic, out of ideas

[veikra]

Re: LG plasma 50pk550 EAY60968801

I found the schematics here https://drive.google.com/file/d/0Bzv...N6d1RKS1k/view

From what I can see, I get 5v for a little while then error detect on the header. I think there is 2 source of 5v, the second not working and the voltage drops. 130V 160V on the PFC OUT point of the schematic.

[tw2005]

Re: LG plasma 50pk550 EAY60968801

Have you gone over this real closely and resoldered all the cracked joints?

Just repaired two of these both had broken solders and lots of them. Was definitely the fault.

[veikra]

Re: LG plasma 50pk550 EAY60968801

yes, I did go over it on all the major components. I dont have a microscope though!

What were your symptoms? I have Rl101 clicking on and off and no stable 5v standby

[tw2005]

Re: LG plasma 50pk550 EAY60968801

Without measurements. I would say it had stdby. Red light then relay latch white light then immediately relay unlatch back to standby. Did not have repeatedly clicking

[veikra]

Re: LG plasma 50pk550 EAY60968801

microcontoller m81f4316 gets 5v, turns on relay rl101. That I know.

From my understanding, the relay sends power to the emiter of opto PC102 which activate the transistor side. So m81f4316 should get 4.5V on r03 (pins 28 ) when rl101 is activated.

Is that correct? Because I get nothing on that pin 0V

[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

[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.

[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

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

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

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.