Vizio VP422 won't turn on.

[budm]

Re: Vizio VP422 won't turn on.

If the MOSFETs are not shown as shorts then remove IC U8301, easier way will be removing the two jumpers wires for the GND return of the IC.

[Malachi]

Re: Vizio VP422 won't turn on.

If the MOSFETs are not shown as shorts then remove IC U8301.

I don't know what an IC is.
Thanks guys but we have gone past my skill level. I'd be able to remove U8301 but I'd never get it or a replacement back on, so I'm done with this.

If you guys believe it to be a power supply board, I can wait till one comes along at a good price or scrap the TV.

[budm]

Re: Vizio VP422 won't turn on.

See post 81, you can remove jumpers instead.

[dick_barton]

Re: Vizio VP422 won't turn on.

Don't give up when you're so close to the finishing line. Have a try. As you said if you fail then you can look for a replacement board at that time.

[Malachi]

Re: Vizio VP422 won't turn on.

Ok budm but will there be any changes since there is no fuse in there?

[budm]

Re: Vizio VP422 won't turn on.

see post 81 about removing the jumpers to isolate IC U8301.

[Malachi]

Re: Vizio VP422 won't turn on.

Thanks. I'll try that tomorrow. I have to spend some quality time with the wife. ��

[dick_barton]

Re: Vizio VP422 won't turn on.

Ok budm but will there be any changes since there is no fuse in there?

You don't need the fuse in place because you are looking for a short circuit which is there whether or not the fuse in place.

[Malachi]

Re: Vizio VP422 won't turn on.

You don't need the fuse in place because you are looking for a short circuit which is there whether or not the fuse in place.

Ok, now I understand it a little more.
Thank you.

Do the resistance readings on the Q components look bad?

[Malachi]

Re: Vizio VP422 won't turn on.

If the MOSFETs are not shown as shorts then remove IC U8301, easier way will be removing the two jumpers wires for the GND return of the IC.

They are under a big heatsink which I'd have to remove and to remove that, I'd have to remove a u bunch of other components.

Some of the components are screwed onto the heatsink. How the heck can you get a screwdriver in there? I have a ratcheting and a 90 degree screwdriver but there still isn't enough room.

[dick_barton]

Re: Vizio VP422 won't turn on.

I don't know what an IC is.

IC = Integrated Circuit
They come in all shapes and sizes dependant on their function. Identified by the unique numbering on top

[dick_barton]

Re: Vizio VP422 won't turn on.

To move forward why don't you lift the links budm suggested and check to see if you still have 0.5 ohms between Points A to Point B.

[Malachi]

Re: Vizio VP422 won't turn on.

To move forward why don't you lift the links budm suggested and check to see if you still have 0.5 ohms between Points A to Point B.

I can't. They are underneath a huge heatsink. See my post above.

[vinceroger69]

Re: Vizio VP422 won't turn on.

can you just unsolder one side of the link s and push it through the board to stop it making contact ? to do the tests

[dick_barton]

Re: Vizio VP422 won't turn on.

You could as a last resort use a sharp knife to slice the copper track, about 1-2mm apart and lift the copper away using your soldering iron. This will isolating the two halves. After the test to reconnect, scratch the green resist off both sides and solder across.

[Malachi]

Re: Vizio VP422 won't turn on.

can you just unsolder one side of the link s and push it through the board to stop it making contact ? to do the tests

I don't think so. They are completely under the heatsink. Even if I do manage to push them through, I'd never be able to get them back on as the lifted part would be under the heatsink.

[Malachi]

Re: Vizio VP422 won't turn on.

You could as a last resort use a sharp knife to slice the copper track, about 1-2mm apart and lift the copper away using your soldering iron. This will isolating the two halves. After the test to reconnect, scratch the green resist off both sides and solder across.

I guess I can try that. Let me mull it over. Lol. I'm scared.
Why do I have to lift the copper away? If I cut a thin section out and break the connection, isn't that good enough?

[dick_barton]

Re: Vizio VP422 won't turn on.

I guess I can try that. Let me mull it over. Lol. I'm scared.

Nothing to be scared of. Sharp knife. Cut positively across the track x 2. Using your soldering iron heat up the piece you have isolated and it should lift off.

Grab a scrap board and try it

[Malachi]

Re: Vizio VP422 won't turn on.

Good idea about a scrap board.
Found a bad Ysus board to an lg plasma. Even has a fuse with the correct specs on it.
Glad I keep everything. Lol

[vinceroger69]

Re: Vizio VP422 won't turn on.

I don't think so. They are completely under the heatsink. Even if I do manage to push them through, I'd never be able to get them back on as the lifted part would be under the heatsink.

or remove both and solder a wire link on the underside of the pcb.