LG 50PB560B completely dead

[mattpd]

NO signs of life with this one, although power supply seems to be working. Can someone check these voltages? This is with the power board out of the TV and on the bench.

VA = 55v
VS = 205v
17v = 17v
5.2v = 5.18v
AUTO_GND = 3.5v
M_ON = 0.63v (what's this and why is it so low?)
AC_ON = 5v
RL_ON = 1.13v (what's this and why is it so low?)
17v_DET = 2.5v
VS_ON = 0.68v (what's this and why is it so low?)
VS_DET = 2.8v

Main voltages seem to be present. I am concerned about the low readings though. I think they are ENABLE signals that I probably need... Can anyone enlighten me?

[mattpd]

Re: LG 50PB560B completely dead

Just measured with the board installed.

All voltages are 0v.

If I unplug the power harness to the main board all voltages return to normal.

Bad main?

[ReeceyBurger123]

Re: LG 50PB560B completely dead

Yeah looks like mobo to me, bridge Pson to gnd and Vson to rlon see if Psu comes on.

[budm]

Re: LG 50PB560B completely dead

pictures of the board and the board P/N?
Is this your board?
LG EAY63168601
http://www.shopjimmy.com/lg-eay63168...upply-unit.htm
With board by itself, are you getting close to 400VDC between the two legs of the main filter caps?
It must be working otherwise you will not have Vs, Va, 17V if the PFC Voltage booster is not working because Vs/Va required boosted Voltage to work.
What DCV do you get on those pins when you have the board all hooked back up?

[mattpd]

Re: LG 50PB560B completely dead

pictures of the board and the board P/N?
Is this your board?
LG EAY63168601
http://www.shopjimmy.com/lg-eay63168...upply-unit.htm
With board by itself, are you getting close to 400VDC between the two legs of the main filter caps?
It must be working otherwise you will not have Vs, Va, 17V if the PFC Voltage booster is not working because Vs/Va required boosted Voltage to work.
What DCV do you get on those pins when you have the board all hooked back up?

Yes, that is my board.

398v between the caps with the board out.

168v when I connect the main board power harness.

Apparently this power board is a replacement. The owner thought it would fix the problem but it did not.

[mattpd]

Re: LG 50PB560B completely dead

Yeah looks like mobo to me, bridge Pson to gnd and Vson to rlon see if Psu comes on.

I don't see a PSon label anywhere.

[budm]

Re: LG 50PB560B completely dead

Yes, that is my board.

398v between the caps with the board out.

168v when I connect the main board power harness.

Apparently this power board is a replacement. The owner thought it would fix the problem but it did not.

OK, the PFC Voltage booster is working as I thought. The board may be using ACTIVE LO signals for the commands.
So those readings you took post 1 when the board is out on the bench and not connected to other boards, now we need to get the readings when all the boards are connected back in place and power is activated.

[mattpd]

Re: LG 50PB560B completely dead

OK, the PFC Voltage booster is working as I thought. The board may be using ACTIVE LO signals for the commands.
So those readings you took post 1 when the board is out on the bench and not connected to other boards, now we need to get the readings when all the boards are connected back in place and power is activated.

Measure with everything installed.

VA = 0v
VS = 0v
17v = 0v
5.2v = 5.2v
AUTO_GND = 0v
M_ON = 0v
AC_ON = 5v
RL_ON = 0.2v
17v_DET = 0v
VS_ON = 0v
VS_DET = 0v

I pulled the main board to troubleshoot it and I am finding continuity on a bunch of the SMD caps. Do schematics for these types of boards ever get released?

[RCA2000]

Re: LG 50PB560B completely dead

have you UNLOADED the VS and VA lines yet--to the Y-sus and Z sus boards...and THEN checked to see what the other run voltages look line?

If...after you unhook the VS lines to these boards it DOES come up...even if ONLY for a few seconds and then DROPS...THEN it indicated a Y or Z_sus problem...NOT a main (signal board) problem.

If...after doing this..the other voltages do NOT return...then you DO have a bad signal board.

BTW--the boost converter will NOT normally boost the voltage during standby...ONLY during RUN..on the PS.

[mattpd]

Re: LG 50PB560B completely dead

have you UNLOADED the VS and VA lines yet--to the Y-sus and Z sus boards...and THEN checked to see what the other run voltages look line?

If...after you unhook the VS lines to these boards it DOES come up...even if ONLY for a few seconds and then DROPS...THEN it indicated a Y or Z_sus problem...NOT a main (signal board) problem.

If...after doing this..the other voltages do NOT return...then you DO have a bad signal board.

BTW--the boost converter will NOT normally boost the voltage during standby...ONLY during RUN..on the PS.

Same result with VS/VA unhooked, must be bad main board. Any way to troubleshoot a main board? as there are none for sale for a decent price. I am detecting a short across some of the SMD caps.

[Diah]

Re: LG 50PB560B completely dead

Not main board, just focus on signal parts, you have short some where.

[jczarniak]

Re: LG 50PB560B completely dead

Same result with VS/VA unhooked, must be bad main board. Any way to troubleshoot a main board? as there are none for sale for a decent price. I am detecting a short across some of the SMD caps.

I've got a similar problem with my TV.
Did you managed to fix it, please?
If yes, where the problem was?
Thank you.

[ReeceyBurger123]

Re: LG 50PB560B completely dead

Ignore Diah, also check Vs on signal and Rl on if they are missing the Mb is faulty. Maybe run the test patterns.

[jczarniak]

Re: LG 50PB560B completely dead

Ignore Diah, also check Vs on signal and Rl on if they are missing the Mb is faulty. Maybe run the test patterns.

Thank you for answer.
This is my case:
TV is not switching on, standby light appears for about 1 second after disconnecting power cable.
Power supply has got Vs and Va present, correct voltages.
Thank you for any help.

[ReeceyBurger123]

Re: LG 50PB560B completely dead

You can run the test patterns with the Mb disconnected. Just jumper the ext gen pins on the control board and unplug the Lvd cable and the set will power on.

[jczarniak]

Re: LG 50PB560B completely dead

You can run the test patterns with the Mb disconnected. Just jumper the ext gen pins on the control board and unplug the Lvd cable and the set will power on.

Thanks a lot.
Which pins these are, please?
Attached photo.
Thank you very much.

[cliff_hootarski]

Re: LG 50PB560B completely dead

EXT AUTO GEN pins top right of the big chip in the middle.

[jczarniak]

Re: LG 50PB560B completely dead

EXT AUTO GEN pins top right of the big chip in the middle.

Done.
Nothing is happening.
Next step, please?

[cliff_hootarski]

Re: LG 50PB560B completely dead

Did you disconnect the LVDS cable? The blue colored connector.

[jczarniak]

Re: LG 50PB560B completely dead

Did you disconnect the LVDS cable? The blue colored connector.

Yes, I did. Blue colored cable disconnected.
Also checked with connected and disconnected power cable to main board.
Still same.
You my only hope, what's next step, please