LG 60PC1D-UE picture messed up

[mmartell]

Re: LG 60PC1D-UE picture messed up

I had a meter that would not measure the ysus voltages that weren't with repsect to chassis ground. Perhaps your readings are erroneous.

I don't see where you ran the logic board test patterns ? Have you tried using hot and cold air on the main board ?

[tom66]

Re: LG 60PC1D-UE picture messed up

Vsc = for the buffer boards. Scans the rows of the picture and in conjunction with Va is used to program each subfield. (Typically 10 SF per frame, 60Hz frames, 600Hz program rate). Without Vsc, generally would expect overdischarged picture similar to buffer board failure.

Vsetup = Reset voltage for the panel and discharge initialisation. Initialises the discharge and erases previous pixels. Without Vsetup, generally would get dark image with few pixels lit.]

Menu and OSD would depend on the intensity and could appear good/bad depending on the faults at work.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

what are vsc and vsetup voltages responsibolities?

with both tested out of range would i get a picture?

would menu osd work and show up good?

i really want to fix this heavy beast of a tv....

[tom66]

Re: LG 60PC1D-UE picture messed up

I don't know, but the pins are all in parallel so I'd expect a common voltage. 5V seems reasonable.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

and tom.....the top 4:pins on p3 from y to logic are all testing 5v....

other 3 are 0v....gnd?

[shelby5041]

Re: LG 60PC1D-UE picture messed up

ok thanks.....the odd thing is when i hit menu button while on a/v input i get a perfect menu image even with no vsc vsetup

but a/v video signal from dvd messed up

and if im on tv input over the air...menu display is messed up as well as tv signal messed up

im hoping someone has same tv with same issue who can solve my issue

i appreciatr ur help tom....

ive narrwed it down to power from y to logic.that is affecting vsc vsretup....but what board is at fault is the missing link

[tom66]

Re: LG 60PC1D-UE picture messed up

No, I don't think it's a PS issue

You gotta understand you're not isolating shorts when disconnecting the data connections. Those are control signals which control the operation of various components on the board. So removing them it's just like turning off part of the board.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

could be p/s issue?

if i disconnect 5v power cable from p/s to y i get good vsc and vsetup

but im sure that 5v powers the logic board which is powered by 5v......when i dosconnect the p/s 5v cable on y the lights on logic are off....

when i have all cables connected and no vsc or vsetup voltages.....i still get good 5v to logic

[tom66]

Re: LG 60PC1D-UE picture messed up

It's not easy if you have no experience with one, also generally would need to be a digital scope as it's hard to get an analogue scope to lock onto the complex waveforms.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

my neighbor has an oscilliscope

would you be able to guide us where to test?

[tom66]

Re: LG 60PC1D-UE picture messed up

As I said, no idea at this point without a scope.

I could probably solve this in a few minutes if I had it in front of me, but it's not unfortunately.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

hey...could the logic and y be bad?

i have not tried connecting both new y and new logic together at same time.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

ok thanks.....what other board could i replace to solve issue?

i may just toss tv in trash.....it may be non repairable.

[tom66]

Re: LG 60PC1D-UE picture messed up

No idea then. Not without scoping stuff. Sorry.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

and i replaced y board.....no change

[shelby5041]

Re: LG 60PC1D-UE picture messed up

i replaced logic control board.....no change

[tom66]

Re: LG 60PC1D-UE picture messed up

P3 is just the cable that sends 15V power for gate drive. Removing it will remove the transient short issue that is causing your problem, either on the Y or the control board. I suspect though that your issue is caused by incorrect control signals from the control board, but I cannot confirm my suspicions without a scope.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

here is pic of back of tv.....

not sure what other boards could be the issue of the problem im having

i do not believe it is y board or logic board since i replaced both boards and no change in symptoms or voltages.

[shelby5041]

Re: LG 60PC1D-UE picture messed up

actually its p3 cable not p300

here is a photo of y

im going to take a pic of back of tv..maybe someone can see something else that could be causing the issue

[shelby5041]

Re: LG 60PC1D-UE picture messed up

more info..there are 2 cables that go directly from logic to y board

one is a multi pin harness labeled p300 and the other is a wide flat ribbon cable

before i was disconnecting both cables....but if i just disconnect the p300 harness from logic to y i get good vsc and vset up on y...so now i have narrowed it down to just one connector that causes bad vsc and setup

i believe the p300 cable is a power sending cable

any ideas?