LG 50PS60 Sound but no picture Ysus board EBR6183001

[goldbird78]

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

see pic's

No worries.
Post a clear, detailed shot of your Y-sustain board and I'll highligth what you need to poke at.

[tom66]

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

I need one of the opposite side of this showing the white connectors
https://www.badcaps.net/forum/attach...8&d=1520190112

[goldbird78]

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

Here you go

[goldbird78]

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

these one may be better

[tom66]

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

Ok you'll want to probe either side of that green resistor on the left hand side...just near the silver capacitor and the big red capacitor, and the text "SOLDERING"

Settings for probe: Switch to 10X (if switchable), if not check the probe says 10X (making it a fixed 10X probe which is fine), black lead on probe connected to the chassis of the TV, the frame near the Y-buffer board usually works ok. Probe on the points mentioned above.

Settings for scope: Trace focused and centred (use beam finder if available). Trig auto mode. 10V/div (equivalent to 100V/div on 10X) for channel 1, with probe connected to channel 1. Sweep on channel 1, turn off dual/chop mode. Time 500us/div. If there is a 10X scale for the horizontal, turn it OFF. Coupling for trigger DC. Coupling for channel should also be DC.

When the set turns on, you should see something filling the screen. It won't be stable for now, but we need the second probe to sort that out. Hopefully you have one. If not, we will need to try to find the best trigger setting to get a stable display.

[goldbird78]

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

attached is my scope, i cant find some of the settings you recommend.

[goldbird78]

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

Attached is what the scope was reading before and after the resistor. And my Oscilloscope settings below and in picture. Yes I do have a second probe.

Ch1 set to DC
Volts/div set to 20 and middle knob pulled out for x5
Vert mode Ch1
Sweep mode Norm
Slope Positive
Coupling DC
Source Ch1
A Sec/Dev set to 50 and middle knob pulled for x10
B Sec/Dev Set to .5 but know idea what this should be or what it does.
Hor mode A

[tom66]

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

Set sweep to Auto.

Hor mode to "A"
Vert mode to CH1

Set all "CAL" dials to calibrated position (until they click at CAL)

Trigger source to CH1

I think "A" time is most important on this scope, "B" time is only for delay time, and not relevant for this application.

[goldbird78]

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

Done. attached is what I am getting on the scope before and after the resister

Set sweep to Auto.

Hor mode to "A"
Vert mode to CH1

Set all "CAL" dials to calibrated position (until they click at CAL)

Trigger source to CH1

I think "A" time is most important on this scope, "B" time is only for delay time, and not relevant for this application.

[tom66]

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

OK, show me what you get at 5ms/div...starting to look more reasonable now.

Can you also attach a pic of your control board. Need to locate the VS_DA point.

[goldbird78]

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

See pic

OK, show me what you get at 5ms/div...starting to look more reasonable now.

Can you also attach a pic of your control board. Need to locate the VS_DA point.

[tom66]

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

OK, your VS_DA point is just to the right of the main big chip on that board.
Show me the 5ms/div trace and we'll go from there.

[goldbird78]

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

Here you go. Thx

OK, your VS_DA point is just to the right of the main big chip on that board.
Show me the 5ms/div trace and we'll go from there.

[tom66]

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

wait, was that the plasma Y-sustain output or VS_DA?
Think I may have confused you - still want you to probe Y-sustain output - but keep an eye on VS_DA for future uses...just need to make sure you're all set up first...

[goldbird78]

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

previous was the VS_DA, Attached is the Y on both sides of the resistor.

wait, was that the plasma Y-sustain output or VS_DA?
Think I may have confused you - still want you to probe Y-sustain output - but keep an eye on VS_DA for future uses...just need to make sure you're all set up first...

[tom66]

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

Cool, that's looking a lot better
OK, now hook up the channel 2 of the scope up to VS DA.
Set trigger source to channel 2
Set trigger coupling to AC and set the trigger level to the centre position (zero)

The waveform should now be a lot more stable, is it?

You may want to find a way to keep the probe on VS-DA...such as soldering a wire to the pad or a nearby component or enlisting a trusted helper...

[goldbird78]

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

Done, It looks a little better but I noticed there is not much difference when I remove the probe from VS DA

Cool, that's looking a lot better
OK, now hook up the channel 2 of the scope up to VS DA.
Set trigger source to channel 2
Set trigger coupling to AC and set the trigger level to the centre position (zero)

The waveform should now be a lot more stable, is it?

You may want to find a way to keep the probe on VS-DA...such as soldering a wire to the pad or a nearby component or enlisting a trusted helper...

[tom66]

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

OK, now set the time base to 1ms/div.
We want to see a waveform that is "locked" in time. So the scope starts at the same point on the waveform every time.
An oscilloscope normally uses a trigger signal, like VS_DA, to synchronise the scan of the electron beam across the display.

[goldbird78]

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

Ok, I have also included a .1 & .2 ms/div. See pic's

OK, now set the time base to 1ms/div.
We want to see a waveform that is "locked" in time. So the scope starts at the same point on the waveform every time.
An oscilloscope normally uses a trigger signal, like VS_DA, to synchronise the scan of the electron beam across the display.

[tom66]

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

Are you sure your probe is set to 10X? As the waveform does not look correct for a 10V/div setting. It is way too large - should only be filling around four squares vertically on the display. Also, check the CAL dial for the respective channel is locked in the CAL position.