Vizio vp50 hdtv20a no pic just sound

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

But leave everything else hooked up?

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

But leave everything else hooked up?

Yes, I'd leave everything else connected.

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

VS volts 209.5
VG volts 15.05

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

VS volts 209.5
VG volts 15.05

How about VA?

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

I also was checking the fuses for power and were the main power wires come in there are two fuses one on each side of the plug. The one on the right has 122.7 ac volts and the one on the left has .708 ac volts is that normal or should both have 120 volts?

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

I also was checking the fuses for power and were the main power wires come in there are two fuses one on each side of the plug. The one on the right has 122.7 ac volts and the one on the left has .708 ac volts is that normal or should both have 120 volts?

I believe that's normal. We still need to confirm your VA voltage.

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

Sorry just found the VA 63.9 volts
I had to unplug the buffer board plug that's the only VA pin I see

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

So, it seems that the Y-main and X-main are the only faulty parts. I'd test the components in circuit with the failed caps (mosfets, diodes, resistors, etc) on those two boards then replace as needed. Do you have any other pics from a different angle that show the components on the heat sinks?

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

Ok thank you for your help. Is there any website I can go to for more info on how to check the two boards?

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

I haven't looked around here much, but there may be info on how to do component-level testing. Hopefully, you just have blown caps. The other thing I was thinking is that you should probably remove your buffers and test them for shorts to make sure they're not bad. Sometimes, the pin holes are so small that they're hard to see. Tom66 has some good info on how to test this particular set of buffers @ 4:35 in this video: http://www.youtube.com/watch?v=51SZsfH60EY

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

Give me a min and I will get them to you

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

This is the y-main

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

Same side y-main

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

Other side of y-main, see the bad cap.

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

Y-main

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

X-main

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

X-main here is the other bad cap, between the fuse and the bigger 250v 68uf cap. I already took it out waiting on the new one. Luckily I ordered two one for a spare, then I found the other one blown on the y-main tonight.

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

Other side of y-main, see the bad cap.

Did you check the green fuse next to the cap? I'd also check the transistors on that heat sink.

X-main here is the other bad cap, between the fuse and the bigger 250v 68uf cap. I already took it out waiting on the new one. Luckily I ordered two one for a spare, then I found the other one blown on the y-main tonight.

Yeah, I always order extras. I'd do the same thing on the X-main: Check the components near the cap and check the transistors on the heat sink. It looks like there's a green fuse near that cap, too.

[Swright]

Re: Vizio vp50 hdtv20a no pic just sound

I checked all the green fuses, and they are good. Don't know how to check the transistors.

[capkid]

Re: Vizio vp50 hdtv20a no pic just sound

It's hard to see the markings on the transistors, but I can at least see K2837, which is an N-channel mosfet. I'm guessing that the others are N-channel transistors or diodes, but I don't know.

For K2837, from left to right, you have Gate, Drain, and Source pins. In diode mode on your meter:
(1) Place your red probe on Drain and black probe on Source: Should read "OL" or "1" depending on your meter (no reading).
(2) Reverse your probes: You should get something like 0.5V.

Repeat this test for Gate and Drain:
(1) Place your red probe on Gate and black probe on Drain: You should get something like 2V. <<- may be dependent on your meter.
(2) Reverse your probes: Should read "OL" or "1" depending on your meter (no reading).

The key is that you should get a reading in one direction and no reading in the other direction.