LG 50PQ30 Heatsinks

[pposey]

Hi. On the YSUS board, can you replace the output transitors on the heatsink if they are shorted? And kind of a dumb question (still trying to learn this stuff) i tested them by the troubleshooting manual of this tv and if it says for instance there is suppose to be .38V from point a to b but it shows OL on my meter, does that mean it is screwed up? Thanks

[capkid]

Re: LG 50PQ30 Heatsinks

You should be able to change out a transistor on the heat sink. What is the part number of the component you're trying to test?

[pposey]

Re: LG 50PQ30 Heatsinks

You should be able to change out a transistor on the heat sink. What is the part number of the component you're trying to test?

It is transistor Q34 on the ysus board.

[pposey]

Re: LG 50PQ30 Heatsinks

It is transistor Q34 on the ysus board.

Should i use a npn or a pnp transistor to replace these if there bad? Thanks again

[tom66]

Re: LG 50PQ30 Heatsinks

Neither.
You should replace them with IGBT or MOSFET, exact type being indicated by the part #.

[capkid]

Re: LG 50PQ30 Heatsinks

The part number should be inscribed on the front of the transistor. Q34 is probably the location of the transistor on the Y-Sustain. Are you sure it's bad and that you didn't just incorrectly measure it? Also, if you tested it in circuit, your readings may not be accurate.

[pposey]

Re: LG 50PQ30 Heatsinks

The part number should be inscribed on the front of the transistor. Q34 is probably the location of the transistor on the Y-Sustain. Are you sure it's bad and that you didn't just incorrectly measure it? Also, if you tested it in circuit, your readings may not be accurate.

Oh ok. The part number is 30f124. I tested it a few times and according to the diagram it should have a 2.02v reading but im getting OL on my meter. I measured these readings with the board out of the tv.

[pposey]

Re: LG 50PQ30 Heatsinks

Neither.
You should replace them with IGBT or MOSFET, exact type being indicated by the part #.

Ok, thanks tom! Also i have one more question. I left the tv on for around 30 minutes to see if the heatsinks would warm up and none of them on either the z or y sus did. Does that mean both boards are bad?

[tom66]

Re: LG 50PQ30 Heatsinks

Not necessarily, if the panel is not lit up, the boards will not heat up as they are not pumping current into the panel, this can be caused by a bad control board, bad main board, shorted Y- or Z-sus (one or both)...

[pposey]

Re: LG 50PQ30 Heatsinks

Not necessarily, if the panel is not lit up, the boards will not heat up as they are not pumping current into the panel, this can be caused by a bad control board, bad main board, shorted Y- or Z-sus (one or both)...

Ok thanks there Tom, i was starting to worry alittle bit lol.

Is it normal for so many of these Mosfets to go bad on a heatsink at once? I found 7 just on the YSUS. It is the part number 30f124. It says in the manual that im suppose to get 2.02v when i connect the red lead to the first prong and the black lead on the middle prong but i get OL.

[tom66]

Re: LG 50PQ30 Heatsinks

Which manual are you referring to?
There are often FETs/IGBTs in parallel, so a whole bank can show shorted, but usually only one actually is failed.

[pposey]

Re: LG 50PQ30 Heatsinks

Which manual are you referring to?
There are often FETs/IGBTs in parallel, so a whole bank can show shorted, but usually only one actually is failed.

It is the 50PQ30 training manual. Is there a way to tell which one has failed?

[tom66]

Re: LG 50PQ30 Heatsinks

Remove them and test them out of circuit. Can be frustrating.

[pposey]

Re: LG 50PQ30 Heatsinks

Remove them and test them out of circuit. Can be frustrating.

Alright buddy will do. Seems like alot of work but i am willing to do it. This is my frist plasma im trying to fix. Seems just a tad bit more than an lcd to deal with but i like this kind of thing. I have fixed 3 Lcd tvs so im trying to break the plasma barrier lol. Thanks again for your help. I will be on here as soon as i can test them all and give you an update.

[tom66]

Re: LG 50PQ30 Heatsinks

Plasma TV pictures look so much better than LCD -- it's worth it!

[pposey]

Re: LG 50PQ30 Heatsinks

Just a quick update. I have taken 3 out but with no luck. I think i may be messing them up when removing them. It has OL on all three from the first prong to the second.(Sorry i do not know the name of these prongs) I ordered me and solder sucker to help me get these suckers out. Seems like i have to get it really hot for the solder to even start melting.

[tom66]

Re: LG 50PQ30 Heatsinks

Decent solder wick such as Chemtronics has never failed me.

[pposey]

Re: LG 50PQ30 Heatsinks

Decent solder wick such as Chemtronics has never failed me.

Thanks for the tip! BTW i found a small fuse on the control board which is blown. How do i go about finding one of those bad boys? its a m5v fuse i think.

[pposey]

Re: LG 50PQ30 Heatsinks

http://imgur.com/VWbBlmX


Is this even fixable? Or even worth it?
It is straight underneath a heatsink.

[tom66]

Re: LG 50PQ30 Heatsinks

If that device burned, that will only usually occur due to a FET on the nearby heatsink going shorted.