Vizio VW37L HDTV20A, No picture but good sound

[Scev]

I've got a Vizio VW37L HDTV20A that recently stopped showing a picture. Instead, I get a rainbow colored set of lines. I've done a little research, and think it might be a bad TCON board, or maybe the power feeding the board is no good (both complete guesses on my part)? Can anyone suggest some things to test?

Attached are some pics of the symptoms, as well as the circuit board on the back of the TV.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Noticed Visio voltage regulators seem to be a common problem, so went through and tested all the ones I could find. Any of these look suspect? Also, when double checking I had all the measurements right, my multimeter lead accidentally slipped between pins 1/2 of U16 connecting them together. So U16 is now 0V on all pins, and so is U44. Did I kill U16 or pop a fuse?

U15
1084
0721CL
2.08
3.32
5.11

U16
7805CT
REH651G
10.97
0
5

U17
AMC1117
F0736J
2.08
3.33
5.11

U19
1084
0721CL
1.24
2.49
5.11

U20
1084
0721CL
0.55
1.80
3.30

U21
AMC1117
F0736J
0
1.24
2.48

U22
AMC1117
F0736J
2.05
3.31
5.15

U44
117GC
1117L
8.4
9.64
10.98

[manstoblame]

Re: Vizio VW37L HDTV20A, No picture but good sound

First off let me say I am not a TV repair person just a tinkerer. That said I suggest cleaning the ribbons that go to the t-con board for starts see if that works, there is something I have heard is better than alcohol that will keep and help protect the connectors. I personally used a little nail polish remover but recommend(rubbing) alcohol as a quick cleaner just to be safe. a little on a white cotton rag and you'll see the difference. If that doesn't work replace the board.
I believe that some of the voltages of the regulators are supposed to drop because they route current to other components at least I think so. Hopefully someone else here will have better help in response to if you shorted anything I really can't say!

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Tried cleaning the connector, didn't fix the issue. Anybody have any knowledge on the voltage regulators? Are the values I posted in the acceptable range? Any idea what I broke by touching pins 1/2 together on one of them (see a couple posts above for details)?

[Glitcher]

Re: Vizio VW37L HDTV20A, No picture but good sound

From the measurements you have before you touched the pins I would guess that U16 is the biggest regulator on the board? You may have shorted it out.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

I was thinking that as well (shorted out U16). However, wouldn't one of the three pins on U16 be the input? All three pins read 0V now, so that has me thinking I killed whatever feeds U16, but I have no idea how to figure out what that would be.

[Glitcher]

Re: Vizio VW37L HDTV20A, No picture but good sound

From the previous readings the 2nd pin is reading 0v so this might be ground? Not exactly sure, but then it would kind of make sense if it shorted to ground. The input would go to ground and read 0v? That's just my theory with my limited electrical knowledge lol.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Glitcher, that sounds about right, but they were only connected together for a second. So something must have blown up, I just don't know how to figure out what that was.

[budm]

Re: Vizio VW37L HDTV20A, No picture but good sound

That U16 is fed by the 12v from the power supply through a SMD fuse, I see two SMD fuses on that main board close to the white connector that goes to the power supply.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Thanks for the tip budm. I tested each and F2 is open, so that must be the one I blew. So....

1) Any place I can pick up a SMD fuse locally (Radio Shack, etc), or do I have to order them?

2) Once I fix my mistake, any troubleshooting tips to find the cause of my initial problem (no picture)?

Scott

[budm]

Re: Vizio VW37L HDTV20A, No picture but good sound

You can use standard 3AG body size 3A fuse and the fuse holder from Radio Shack and just solder the two wires from the fuse holder to the SMD fuse's ends without removing the old fuse (if you get the SMD fuse, you can solder the new one right on top of the old fuse).
You need to install the new fuse and check the voltages again to see if anything else is damaged.
By the way, pin 1 of that 5V regulator is the input pin, pin2 (middle pin/tab) is the ground pin, so you just accidentally ground the 12V to ground through the fuse.
The pictures that you shown looks like the T-CON or the panel problem.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Installed a new fuse, all the voltage regulator values I previously posted are still valid...doesn't look like anything else is damaged. What can I test to try and narrow down what the problem is?

[budm]

Re: Vizio VW37L HDTV20A, No picture but good sound

I would look at the T-CON board next. Pictures of the T-CON?

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

I believe this is the TCON board?

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Bump for any tips on what I can test on TCON board...

[budm]

Re: Vizio VW37L HDTV20A, No picture but good sound

Have one of the two ribbon cables connected one at time and see what you see on the screen.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

One thing I'm not sure if i mentioned...the first pic in my original post is with no source, the last picture in my original post was with a HDMI signal present. You'll notice the color difference. The below tests are with no source connected.

Right side disconnected...



Left side disconnected...

[tom66]

Re: Vizio VW37L HDTV20A, No picture but good sound

If you have not already, I would be fiddling with the tab bonds.

[Scev]

Re: Vizio VW37L HDTV20A, No picture but good sound

Fiddle with tab bonds? I'm not sure what this means...

[budm]

Re: Vizio VW37L HDTV20A, No picture but good sound

I am curious, If you have a source hook up and per second picture (left cable's disconnected). Will you see normal picture half the screen?