LG 50PS60 Sound but no picture Ysus board EBR6183001

[goldbird78]

I have an LG 50PS60 that has Sound but no picture Ysus board EBR6183001 EAX60982501, I am 99% sure it is the Ysus board because I swapped a board from my other identical TV and it worked. I would like to take a shot on fixing the board, anyone know what component / components may have failed. I have checked all my voltages from the main board and all are very close to spec and I have checked all the fuses on the Ysus board and all are good. Also I know bad buffer boards can kill the Ysus board, if there bad/shorted buffer will this kill the Ysus board instantly or after the TV has been on for a while. Thx

[mmartell]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Post a picture of your ysus.

Measure and post your main voltages with the non working ysus installed, VS VA Vsc and -Vy. And Ve on the xsus for good measure.

[mmartell]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

And flip it over and have a look for cold solder joints, especially on MOSFETs and diodes attached to heatsinks and under any transformers.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Attached is a picture of the screen, the Ysus board & the voltage ratings. I am 95% sure the Zsus board is good because it works perfect in another TV.

Ysus Voltages

V 195.1
VA 59.94
5v 5.06

Zsus Voltages

195.1
5v 5.06
15v 18.01

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

I have ohmed out the YSus buffers and they appear to be good. I have two questions keeping in mind I have two exact same TV's so testing is very easy.

1) If I put what I think is a bad Ysus board in the good TV just to verify if it is bad will it damage or short any other board or component in the TV ?

2) For the slight chance the Y buffers are bad and I put a good operating Ysus board in to test the TV, would it kill the Ysus board instantly or after a few min running ?

Thx

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Update, Y buffers are good, ohmed them out to floating ground. Installed working Ysus board from my other TV and now its working so the problem is 100% a bad Ysus board. When the bad board is in the TV when I turn it on sometimes it will give a blue & red pixel screen and sometimes it will be very dark with blotches of color. Input voltages are good from the power supply, all fuses are good and solders visually look good. Any thoughts on what to look for or what might be bad on the board would be appreciated. I did notice the coil by the fuse is lose but i ohmed it out and it appears to be fine. Thx

[will62]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Hey goldbird78, mmartell asked for you to list your -Vy and Vscan voltages. It's kind of late, so I may have missed where you listed them. Those two are adjusted on the Y-sus, so that's probably a good place to start. Looks like your set is looking for a -Vy of -180, and a Vscan of 150. The attached diagram may help.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Hey goldbird78, mmartell asked for you to list your -Vy and Vscan voltages. It's kind of late, so I may have missed where you listed them. Those two are adjusted on the Y-sus, so that's probably a good place to start. Looks like your set is looking for a -Vy of -180, and a Vscan of 150. The attached diagram may help.

I could not find those test points before, I will check them out and report back. Thanks.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Hey goldbird78, mmartell asked for you to list your -Vy and Vscan voltages. It's kind of late, so I may have missed where you listed them. Those two are adjusted on the Y-sus, so that's probably a good place to start. Looks like your set is looking for a -Vy of -180, and a Vscan of 150. The attached diagram may help.

The -VY on my board was is a different location.

Readings

VSC 150.4
-VY 180

[tom66]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Try adjusting the SET UP and SET DOWN pots on the board (maybe RAMP UP / RAMP DOWN) and see if that has any effect.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

The SET UP made no change, the SET DOWN did make a change to the color but to the static/snow in getting on the screen.

Try adjusting the SET UP and SET DOWN pots on the board (maybe RAMP UP / RAMP DOWN) and see if that has any effect.

[tom66]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Is the picture also jumping up/down? Could you show us a video of the issue?

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Yes the picture jumps around a little and is unstable, hard to see on the video's. Also the picture goes lighter and darker. See youtube links below

https://www.youtube.com/watch?v=RpRADd-jPHY

https://www.youtube.com/watch?v=n_hOS5x4yeU

[tom66]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Give the chips highlighted a blast of freezer spray and see if anything happens.

You can use a can of air if inverted to produce freezer spray. Compressed butane also works, please beware of the flammability hazard around high voltage though.

For the chips at the top you can directly use freezer spray on them while the set is on, careful to make sure the liquid does not drip down the board. You may want to lay the TV down for this, but in such a way that you can observe the screen. (Or apply what I wrote below for top ICs too.)

For the ones on the bottom, either make sure the board is OFF and allow the condensation to fully evaporate (except around the top of the chip) OR you can damp a piece of cotton wool and dab it on top of the IC to cool it down. Be careful of the high voltage in this part of the circuit.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Hi Tom, thanks for the help. I got them nice and frosty white waited 30 second for any residue to evaporate but unfortunately no luck.

Give the chips highlighted a blast of freezer spray and see if anything happens.

You can use a can of air if inverted to produce freezer spray. Compressed butane also works, please beware of the flammability hazard around high voltage though.

For the chips at the top you can directly use freezer spray on them while the set is on, careful to make sure the liquid does not drip down the board. You may want to lay the TV down for this, but in such a way that you can observe the screen. (Or apply what I wrote below for top ICs too.)

For the ones on the bottom, either make sure the board is OFF and allow the condensation to fully evaporate (except around the top of the chip) OR you can damp a piece of cotton wool and dab it on top of the IC to cool it down. Be careful of the high voltage in this part of the circuit.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Btw, I do have a donor board, so if there is anything you feel that may need replaced I can give it a shot.

[tom66]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

I think a likely problem is those ICs but I can't be sure.
It's difficult to trace this problem without an oscilloscope, do you have one?

[mmartell]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

I repaired a 50PS30 recently. It too had good voltages but an odd pic and the set_up pot had no effect on the picture at all but the other pots did. It was the large 2.2ohm resistor feeding the pot, in your case R363. May as well measure it.

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

No oscilloscope yet, that is on my "to get list" Are there reasonably priced one's for a hobbyist ?

I think a likely problem is those ICs but I can't be sure.
It's difficult to trace this problem without an oscilloscope, do you have one?

[goldbird78]

Re: LG 50PS60 Sound but no picture Ysus board EBR6183001

Thanks, I sure will and report back.

I repaired a 50PS30 recently. It too had good voltages but an odd pic and the set_up pot had no effect on the picture at all but the other pots did. It was the large 2.2ohm resistor feeding the pot, in your case R363. May as well measure it.