LG42PX4DV 3 board Change

[scooby-doo]

Hi

Can someone just clarify something please, I believe the LG42PX4DV had a major problem where the repair is changing the sus boards etc.

Is it true the symptoms for this is that it blows the fuses in the sus boards, the reason why I ask is that I have one of these sets and none of the fuses are blown and I get nothing from the set, no sound or picture, the led goes from red to amber then to green then back to red.

I dont want to go out spend my hard earned cash on the boards to find it was a psu issue.

Can some please clarify the symptoms for this tv please.

Thanks in advance

[Ohm Supplies]

Hello,

Whats the number on the y-sus?

regards
Andy

[scooby-doo]

Hi

6871QYH048B

WL42065J830419

[Ohm Supplies]

i think the PDP used with this board is a v8, the 3 board kit i think you mean is for a v7, so it wont do.

have you checked the IPM's on the Y-sus for a short?

regards
Andy

[scooby-doo]

Hi Andy

I had a another quick look and found that there is no cable going from PSU (P806) to the z sus board (P1)

Without sounding stupid and without having to wait a few days for a new cable I am going link them up myself, now the stupid bit, do I simply attach:-

PSU (pin labelled vs) to x-sus (pin labelled vs)
PSU (pin labelled vcc) to x-sus (pin labelled+5v)

etc etc

[Ohm Supplies]

Isn't it marked up on with side of the board?

Before doing that, I'd be asking the question "were is the cable and why has it been removed?"

[scooby-doo]

Hi

Thats a dam good question, but I bought the TV at a price I couldn't refuse(£15 with stand & remote) I was surprised it even powered up at all.
Its another reason I don't really want to go out and buy parts if the TV is shot and for the sake of making a cable its worth a test, at no major cost.

Will also check the y sus board like you mentioned and write back later today.

Thanks again for your help.

[scooby-doo]

I have made the cable and tested, what I have found is like mentioned earlier the light goes from red/amber/green/red.

If I disconnect the y sus board the TV green led stays on.

So I am guessing the short you mentioned is apparant....erm what normally blows on these things.

[Ohm Supplies]

you mean the IPM? I'd also check the y-buffer

[scooby-doo]

Ermmmm IPM???

Do I test the buffer in the same way, disconnect it to see if the led light goes to red again, or will disconnecting these make the led respond in this way as its detected the buffer has been disconnected.

Thanks again

[scooby-doo]

Hi

Done a bit more searching and could you confirm I have done this correctly

To test this board I carried out this test on Diode mode of the DMM

Forward Test
1.GND(＋), Sus-out(－) reading 379
2. Sus-out(＋), Vs(－) reading 378

Reverse Test
1. GND(－), Sus-out(＋) reading Infinity
2. Sus-out(－), Vs(＋) reading Infinity
With these readings can you tell me if the IPM has fluffed it.

Thanks again

[Ohm Supplies]

Hello,

There's no short from those readings, however unfotunatly you don't always get a short on the V-sus,

I'll be changing an ic soon and measure some of the lines, unless someone else has the definate check for the fault as I know there's at least one LG expert on here 
regards
Andy

[scooby-doo]

Cheers Andy for all your help, like mentioned I dont want to spend loads on the thing, it just seems strange that none of the usual faults I keep seeing are there.

No blown fuse
Seen somewhere mention that a couple of the 5 Fets attached to the heatsink can go down, they are all ok
Then the last test is showing no short, think it did say something about this being 99.9% accurate...I bet I am that 0.1%

Thanks again

[scooby-doo]

Hi

This is a stupidly long shot, everytime I moved this TV I could hear a little rattle so I removed the back again tonight and found his floating around

http://www.inspectabike.co.uk/images/3.jpg

I have searched and searched to see which board it has come off and to where it was originally fitted, not having much luck, my question is that if this has fallen off the y sus board would it/could it give the symptoms I am getting, I do not want to search the boards anymore because my eyes hurt and if I am wasting my time searching then I am going to give up now.

If it could cause the problems then here is the long shot, could anyone supply a high res image of the ysus board so I can identify where the bloody hell this thing goes a little easier.

And if it helps the number on the back is 35347, 68 35k

[scooby-doo]

I think I have found where it belongs, could someone possibly confirm that on the Y sus board if a component is on C7 its location is just left of the little transformer 2 inch below where it says "SOLDERING"

With thanks