LG 60pb560v plasma tv no picture

[vivalabam88]

Hello everyone,

I have a problem with a TV of mine. I would try to explaine as much as possible.
When I put in the power cord. You hear relays clicking that's normal. The TV is starting up right away but not with a picture.
You can use the power button on the TV itself to turn it off again an it reacts normal and shuts off.
You also can turn it on again with this button.
Also with no picture coming.
What I noticed is that the logic board never gives a flashing green led. It also doesn't matter if I disconnect the y-sus and z-sus boards.
The next thing i notice is that the digital audio port on the mainboard lights up when you start up the TV and then slowly goes out after a second or 2. Doesn't come on again if you let the tv on.
I have measured the voltages and they look fine in my opinion.
Vs are good and in range Va also and steady.
The only thing I don't understand is what is the pin 17v-det does.
I m measuring about 3v at that pin.
One more thing is that I slightly hear a ticking noise coming from one of the transformers at the power supply board don't know if that's good or bad. It's not as loud as a relay but just a little tick. And it is constant there every second. But what I mentioned I measure good voltages.
I hope someone can help me with this problem
Especially whit the logic board and the mainboard. How I can test those 2. Or measure some things to be sure where the problem is coming from.

Thanks for your messages.

Ps if I have to upload pictures it can take a little time because I m very busy at the moment.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

Hi,good clear pictures of the back of this TV without cover will help.

By what you are stating,i can't determine if main board is working or not,if sound comes from the input i say it is OK,17V det is to determine if 17V is detected,3V on it is a logic signal probably,if it has 17V where it needs to then that's not a problem,check 5V and 18V at Z-SUS board.

Inspect the plasma panel up close for any kinds of cracks.

Remove power supply connections to the main board and also remove LVDS cable going from main board to logic board(middle of the TV). This will isolate main board as the TV will still power the plasma ON,but the TV will automatically switch on as soon as AC is plugged in.

Logic board doesn't blink is a problem,it is fed 5V from the PSU connector that goes to Y-SUS then routed to logic,check the 17-33 3.3V voltage regulator on that board,forget the red circle on auto-gen,that is after logic board is determined working.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

Thank you for your fast reply . I'll post pictures as soon as possible. And I will check the voltages too. And let you know what it is.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

I have measured the voltages and they are ok 3.27 volt and 4,97v on the logic board. Disconnected the main board but still no green led. The screen I still need to look at for cracks didn't do that yet.

Added some pictures hope they are good.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

I have measured the voltages and they are ok 3.27 volt and 4,97v on the logic board. Disconnected the main board but still no green led. The screen I still need to look at for cracks didn't do that yet.

Added some pictures hope they are good.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

Just also tested the sound. And it works. Plugged my ps3 in and sound is there when I switch screens that I don't see

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

If I know LG logic boards is that they're supposed to blink by only having 5V being supplied to that IC,you may replace the board,maybe wait for another member's opinion.
Try this: disconnect every other cable except the Y-SUS flat from logic board,then see if it blinks.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

Tried to do what you have said about disconnecting al the other ribbon cables but still no changes. The only thing I measured was that the voltages dropped to 1.7v and 3.3v on the logic board.

[R_J]

Re: LG 60pb560v plasma tv no picture

Most of the information I have for other similar LG control boards is that the D1 led should blink indicating the board is working.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hello,

i m back again. orderd another logic board but still the same problem it is not new but used.

not a single blink from this one nether. is there something i can try or measure?

thank you

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

You'll be taking out the Y-SUS and measuring between the pins of these circles on the images.
YSUS
Top side - if the resistors are open that's a sign that something else failed.
Bottom side - I circled IGBTs,MOSFETs and their driver ICs,if you find a short on any of them that's one problem.
ZSUS board i coudn't find any decent pics of bottom,so i circled what you should measure on the solder side of the board, under these heatsinks are the pins of the transistor and diodes.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hello and thank you for your reply,

I hope i have measured it right and i didnt find anything wrong on the ysus board.
but i think i have found something on the zsus board i have made a few pictures of it. i hope you can tell me if i have done it the right way.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

it was d201 i measured both sides go to 0 red and black switched from left to right

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

they are diodes and these are the same pins,cathodes,connected to the same PCB trace,so it's normal that they do that,would only be a problem if that was a transistor,anything below 2k ohm between pins(even if the probe polarity is reversed) is weird.
Do you have VSCAN(Y-SUS checkpoint) and V-ZBIAS(Z-SUS checkpoint).
I forgot to mention to check the Y-buffer output pins for shorts.
https://www.youtube.com/watch?v=3Oq2MsU0XOQ example video on how to do that.
No cracks on panel or anything?
After doing all that and still nothing disconnect the LVDS cable from main to t-con,see if it the panel works(would just be a black screen but it will power up and glow).

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hello thank you for your reply, i have measured the buffer boards and they look ok. the only thing i get is with the bottom buffer one (there are 2 top and bottom). is that there is a reading when i measure it is about 900 on diode mode, NO shorts that drops to zero. (made a picture of that board.

the vscan i cannot find, but the vzbias i have made a photo of.

the zsus board i have measured again. one side it reads 10k and the other side it reads 1.4k for the most transistors. like Q301 for example.

i will take a good look at the screen one more time and reply on that later.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

0.9V on the buffer is OK.Also logic board should've been blinking since you reported 5V going into it,strange.No damage at the panel then?
Before doing voltage measurement,disconnect LVDS from logic board,then solder a jumper/wire between the pins labeled EXT_AUTO_GEN, they are visible at the first picture i uploaded on this post,if everything is working you should get a test pattern at the plasma.
There is no specific VSCAN checkpoint on Y,only VY, so measure that, it is between R254(big 220k next to heatsink) and a pin just for that.
V-Zbias is at those 2 jumper wires at this photo you just send.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

hello,

i tried and solderded the points together. what happens is that it shows a snowy picture for one second and then drops black again. so the screen also looks good. no cracks. and we have a little picture on it thats a small step forward.
what is your opinion about this? also the green led it comming on. 3 times short 1 time long and the goes out for a 2 seconds and then repeats the same cycle.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

There is some sustain problem,measure the VY and ZBIAS while tv displays "snow" and post them here.

[vivalabam88]

Re: LG 60pb560v plasma tv no picture

vy 213V of what i can see my meter isnt verry fast and than it stays at 183V

ZBIAS stays at 124V nothing above that.

[Biruslapio]

Re: LG 60pb560v plasma tv no picture

Well the only thing left to make sure the Y board is not at fault would be VSCAN, but i don't know what reference to use, floating ground or general ground.
I think something may be wrong with the buffers,try leaving only bottom board plugged in the TV, if the same problem occours on only half screen try only top buffer.