60PB660v Lg plasma tv- sound but no picture

[thuss]

Hi I could do with some help on this on.


The tv turns on with sound but no picture/screen does not flash just blank.

All the voltages are there i.e vs 205 va 55.

I have checked the buffers they seem fine- tested them with a multimeter and took one out and turned the tv on - but no half picture.

On the ysus there is no vy voltage and there is no voltage going to the buffers.

On the ysus the mosfets are not shorted. The 5 transistors on the rear seem fine (30f132 ). Nothing is short to chasis.

Ive detached the main board ribbon to tcon and put a jumper auto gen but no test patterns.

Repeated it but this time with zsus detached still no test patterns.

The led on the tcon hasnt flashed in any of the tests.

Can it be the panel or is it the actual tcon board?

Any help would be really appreciated

[R_J]

Re: 60PB660v Lg plasma tv- sound but no picture

I'm not 100% but it does look like a bad control board, I believe the led on the board should either be on or slowly flashing, check that you have supply voltage (5v?) to the board

[Andrew F. Ali]

Re: 60PB660v Lg plasma tv- sound but no picture

i'm not 100% but it does look like a bad control board, i believe the led on the board should either be on or slowly flashing, check that you have supply voltage (5v?) to the board

+100

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

thanks for the replies. One thing I forgot to mention is that the ysus is not generating the 18v supply to zsus.
But I checked the ic201 and the diode is not shorted . Yes there is voltage going to the Tcon (control board)

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

I'm not 100% but it does look like a bad control board, I believe the led on the board should either be on or slowly flashing, check that you have supply voltage (5v?) to the board

I will replace the tcon board and keep you updated- one last question does the ysus feed any voltages to the tcon?

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

I mean logic board not tcon

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

I replaced the logic board but still no picture.

there's still no green led light flashing on the new logic board so I assume I've been given a dud board.

[R_J]

Re: 60PB660v Lg plasma tv- sound but no picture

I was checking this thread which seems similar 60PB6600-UA https://www.badcaps.net/forum/showth...light=60PB6600 and they talk about the led on the ctrl board

I found this on elektroda for a 50PB5600 (same ctrl board)

Hello. Attempting to switch on will only result in the stby LED going out. No vision or sound. All voltages from the power supply present. There is no 18V voltage on the Y module. There is no LED D101 signaling on the logic module. I do not know if "Main" works because there is no "lighting" of the Optical Digital Audio output, but I do not know if it does not light up until the whole TV is fully turned on. I do not know this model completely, it is the first art that hit me. In others, the lack of voltage of 18V on the Y module is almost always a damaged "Scan". There is no easy way to check the combined blocks "Scan" and "Y-Sus". After unplugging the tape between "Main" and "Logic" and shorting Pin 1 and Pin2 connector P222 on "Logic" LED D101 blinks in sequence: long, short, long, short, break etc. screen is still dark. Maybe someone has more experience with this model and will suggest something?

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

I was checking this thread which seems similar 60PB6600-UA https://www.badcaps.net/forum/showth...light=60PB6600 and they talk about the led on the ctrl board

I found this on elektroda for a 50PB5600 (same ctrl board)

Thanks for the links , I've checked the buffers caps they are ok. All the mosfets diodes and resistors are fine.

I just cant find the fault.


One last thing I maybe testing incorrectly are the 4 igbt's on the rear of the Ysus board. I have disconnected all the legs on the igbt (2 legs) and with a different meter on diode test I am getting (no shorts) just OL whichever way I use the probes. I think the igbts are the problem.

[tvtimmy]

Re: 60PB660v Lg plasma tv- sound but no picture

Sometimes they don't short out, they just go open. Seen this many times. I have a super cheap transistor tester that I start with, it will read an open one as a resistor or a capacitor.

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

Just out of curiosity if the igbts were healthy and out of circuit what readings should I get say on resistance or on the diode setting? Thanks

[Pat P.]

Re: 60PB660v Lg plasma tv- sound but no picture

Sounds suspiciously like the problem I'm having with my LG 50pn4500. there is a thread about it. Problems are in the 18v circuit. If this isn't working you won't get the status light to come on.

[thuss]

Re: 60PB660v Lg plasma tv- sound but no picture

update I cannot find the fault it's so frustrating. R559, q507.etc are fine.But still I get no VY voltage on the ysus

(I also replaced the igbts )

Any ideas would be really appreciated