lg 42px5r no picture with sound

[nalle077]

Hello. Got myself a broken set. LG42px5r. I opens it and 4 capacitors were bad on the mainboard. I changed these but it was not functional. Tested fuses and 1 was broken on y-sus board. Changed it but still no go. I have read that it is very common that the y-sus board is broken. I have looked at the ics on the bufferboard but all looks good. Can anyone link to a picture of a ic with a pinhole crater on it so one has something to compare to when looking for problems. So the question is. Is there a way to measure or be sure that the y-sus board is broken. By the way I did not have a 4amp fuse at home so l tested with a 2,5 amp fuse and it broke . I bought the right one and it is good but no picture. Eeeh u should get a picture that says " no connection " or somethin like that even if i dö not have anything plugged in right?

Best regards Marcus

[tom66]

Re: lg 42px5r no picture with sound

You can check from either end of the fuse to the metal back of the panel. If you read close to zero ohms on one or both ends, the IPM is shorted.

I'm not sure about whether the LG 42PX5D is the same, but mine shows No Signal when nothing is plugged in. And most older plasma panels have trouble with deep black so the black pixels will light up with no signal.

[nalle077]

Re: lg 42px5r no picture with sound

You can check from either end of the fuse to the metal back of the panel. If you read close to zero ohms on one or both ends, the IPM is shorted.

I'm not sure about whether the LG 42PX5D is the same, but mine shows No Signal when nothing is plugged in. And most older plasma panels have trouble with deep black so the black pixels will light up with no signal.

Ok, but if the board was shorted, wouldnt the new fuse blow to? I have close to 230 V on the fuse.
And than if the bord is shorted, how can I measure what the fault is?
btw what is IPM :$

[tom66]

Re: lg 42px5r no picture with sound

Ok, but if the board was shorted, wouldnt the new fuse blow to? I have close to 230 V on the fuse.
And than if the bord is shorted, how can I measure what the fault is?
btw what is IPM :$

Not necessarily - if the board is shorted, the power supply will not output the right voltage (it will go into protection mode), and the fuse will not blow.

The IPM is the integrated power module. There are usually one or two of them on the board, and they are the most common failures.

[nalle077]

Re: lg 42px5r no picture with sound

Not necessarily - if the board is shorted, the power supply will not output the right voltage (it will go into protection mode), and the fuse will not blow.

The IPM is the integrated power module. There are usually one or two of them on the board, and they are the most common failures.

ok thanks but as I wrote I have close to 230V on fuse? If it is in protection mode, I dont think the first fuse I mounted would blow either? what happens when it is in protection mode, I have sound as i wrote before, Could I think the IPM is under the big heatsink on the y-sus board?
Is it a hybrid module on thjis one as I have read about in other threads?

[tom66]

Re: lg 42px5r no picture with sound

ok thanks but as I wrote I have close to 230V on fuse? If it is in protection mode, I dont think the first fuse I mounted would blow either? what happens when it is in protection mode, I have sound as i wrote before, Could I think the IPM is under the big heatsink on the y-sus board?
Is it a hybrid module on thjis one as I have read about in other threads?

The Y-sustain can pull a huge current on start up. Did the fuse blow immediately, or after a few seconds?

Not sure about the other threads... the hybrid is the chip under the biggest heatsink. There may be two on some plasmas.

[nalle077]

Re: lg 42px5r no picture with sound

The Y-sustain can pull a huge current on start up. Did the fuse blow immediately, or after a few seconds?

Not sure about the other threads... the hybrid is the chip under the biggest heatsink. There may be two on some plasmas.

The fuse blew after about 10 sec, but that was a 2,5 amp fuse as I did not have a 4 amp fuse at home then.

Is the integrated power module you wrote about the same as the hybrid?

would I have the right voltage if the tv is in protectionmode , and would the sound still work as normal?

[tom66]

Re: lg 42px5r no picture with sound

The fuse blew after about 10 sec, but that was a 2,5 amp fuse as I did not have a 4 amp fuse at home then.

Is the integrated power module you wrote about the same as the hybrid?

would I have the right voltage if the tv is in protectionmode , and would the sound still work as normal?

Yeah, if the fuse started to glow then blew, it was probably the wrong rating. If it blew really quickly, then it's probably a problem with the board.

Hybrid and IPM mean the same thing when talking about plasma TVs. However, you will find hybrids in a lot of other devices, but you will only really find IPMs in plasma TVs.

Depending on the design of the power supply, it may work with a shorted load on the Vs/Va, as the other supplies (e.g. for sound) are separate.

[nalle077]

Re: lg 42px5r no picture with sound

Yeah, if the fuse started to glow then blew, it was probably the wrong rating. If it blew really quickly, then it's probably a problem with the board.

Hybrid and IPM mean the same thing when talking about plasma TVs. However, you will find hybrids in a lot of other devices, but you will only really find IPMs in plasma TVs.

Depending on the design of the power supply, it may work with a shorted load on the Vs/Va, as the other supplies (e.g. for sound) are separate.

ok I understand but why does not the fuse break now?
It holds when the tv is on now. I have about 400 ohm on each side of fuse what would be normal value

[nalle077]

Re: lg 42px5r no picture with sound

Yeah, if the fuse started to glow then blew, it was probably the wrong rating. If it blew really quickly, then it's probably a problem with the board.

Hybrid and IPM mean the same thing when talking about plasma TVs. However, you will find hybrids in a lot of other devices, but you will only really find IPMs in plasma TVs.

Depending on the design of the power supply, it may work with a shorted load on the Vs/Va, as the other supplies (e.g. for sound) are separate.

Hello again.
I dont think you read the hole posts as you only answer half of the questions.
I do not mean to be rude, but I would like to know what to do

Here are my questions:

1: I have 195V on fuse as the Vs is, would it be this way if tv is in protectionmode?

2: I have 375 Ohm on one side of the fuse to ground (with the fuse taken away) and 333 Ohm on the other side to ground. What to think about these values ?

3: how can I measure what the fault is and fix it, I mean if it is an IC that is broken I will bye a new Y-sus card as I dont beleve I can solder that myself, but I would really like to know for sure what is the fault, so I can learn something along the way.

Best regards Marcus

Edit: fixed a spellingfault

[tom66]

Re: lg 42px5r no picture with sound

Hello again.
I dont think you read the hole posts as you only answer half of the questions.
I do not mean to be rude, but I would like to know what to do

Here are my questions:

1: I have 195V on fuse as the Vs is, would it be this way if tv is in protectionmode?

2: I have 375 Ohm on one side of the fuse to ground (with the fuse taken away) and 333 Ohm on the other side to ground. What to think about these values ?

3: how can I measure what the fault is and fix it, I mean if it is an IC that is broken I will bye a new Y-sus card as I dont beleve I can solder that myself, but I would really like to know for sure what is the fault, so I can learn something along the way.

Best regards Marcus

Edit: fixed a spellingfault

I have ADHD. But I'm not easily distrac... SHINY! Okay, being serious, I'm a quick reader. Sorry if I missed anything .

1. Most likely not.

2. Those readings seem bad, but it's not as close to zero as I would expect. It's quite possible the capacitors on the board are reading close to zero if they have not charged up yet - this may be normal. IF you still get 195V when the board is connected then the board is probably not shorted.

3. The #1 failure is the IPM going short circuit, #2 is other components going short circuit. There might be occasional open circuit failures but they are rare.

[nalle077]

Re: lg 42px5r no picture with sound

I have ADHD. But I'm not easily distrac... SHINY! Okay, being serious, I'm a quick reader. Sorry if I missed anything .

1. Most likely not.

2. Those readings seem bad, but it's not as close to zero as I would expect. It's quite possible the capacitors on the board are reading close to zero if they have not charged up yet - this may be normal. IF you still get 195V when the board is connected then the board is probably not shorted.

3. The #1 failure is the IPM going short circuit, #2 is other components going short circuit. There might be occasional open circuit failures but they are rare.

2: I do have 195V when board is connected ( so you dont think the board is shorted)

3: what can the problem be then, do you mean that it is not likely a shorted board and that includes IPM short circuit or other components that are short circuit.

4 What to do now?

Thanks for the help/ Marcus

[tom66]

Re: lg 42px5r no picture with sound

2: I do have 195V when board is connected ( so you dont think the board is shorted)

3: what can the problem be then, do you mean that it is not likely a shorted board and that includes IPM short circuit or other components that are short circuit.

4 What to do now?

Thanks for the help/ Marcus

4. Does the screen glow at all in a dark room?

[nalle077]

Re: lg 42px5r no picture with sound

4. Does the screen glow at all in a dark room?

No it does not glow at all

[tom66]

Re: lg 42px5r no picture with sound

No it does not glow at all

Does this TV have two buffers? (On my 42PX5D, it does.) If so, unplug the upper buffer and see if you get a picture on the lower half. Then repeat for the lower buffer (plug the upper back in.) Do this with power off, of course !

[nalle077]

Re: lg 42px5r no picture with sound

Does this TV have two buffers? (On my 42PX5D, it does.) If so, unplug the upper buffer and see if you get a picture on the lower half. Then repeat for the lower buffer (plug the upper back in.) Do this with power off, of course !

The contacts goes first to the upper bufferboard and from that board to the lower board, if I remove the upper board the lower board does not get any connection? I have tested to disconnect the lower board and there was no difference. Or do you mean that I should disconent all the 6 wires that goes to the screen? , and test it like that?

[tom66]

Re: lg 42px5r no picture with sound

The contacts goes first to the upper bufferboard and from that board to the lower board, if I remove the upper board the lower board does not get any connection? I have tested to disconnect the lower board and there was no difference. Or do you mean that I should disconent all the 6 wires that goes to the screen? , and test it like that?

There is a data cable between the boards but you can disconnect that for this test as we are only wanting to see if the screen glows.

[nalle077]

Re: lg 42px5r no picture with sound

There is a data cable between the boards but you can disconnect that for this test as we are only wanting to see if the screen glows.

No. I cant see anything anyway.

[tom66]

Re: lg 42px5r no picture with sound

No. I cant see anything anyway.

Okay, does the Y-sustain make a faint buzzing sound, at all?

[nalle077]

Re: lg 42px5r no picture with sound

Okay, does the Y-sustain make a faint buzzing sound, at all?

Yes I think so, it is not much but I think it is the same as the z-sus