Vizio VX37L HDTV10A Works perfect except AVI video is distorted

[gijoey198079]

Using cable or digital antenna the picture is perfect and normal, HDMI is normal as well, when you use the AVI inputs the picture is distorted, kinda blurry, and the color is a little off, way too much white and almost looks like a little static.

I have already tried a few different cables and same result, tried it with the wii, dvd player and ps3 all the same outcome.

[tom66]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

Vizios are well known for regulator issues. Such a problem could cause distortion on only the analog inputs.

See this thread for a guide.
https://www.badcaps.net/forum/showthread.php?t=22231

[gijoey198079]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

I got another one here with busted screen all the boards are good, think I should just change out the motherboard and test it? I don't have but $10 in the one with busted screen so it would be easier to do than trace down the issue.

[tom66]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

I would do that.
Then eBay the remaining working boards as they are rare and you should get a good price.

[gijoey198079]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

Think a firmware update may do it?

[martyparish]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

Considering you have two boards, one good one. I would at least try to fix the original(you can use the good one for reference when measuring voltages). As Tom said, it could be a regulator and end up being a cheap fix. (Then you also have a main board to sell!)

[gijoey198079]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

Well I went and pulled the other board and there are a few differences, both are the same exact model but different part numbers on board. Should I change out the psu, main board and t-con just to be on the safe side?

[tom66]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

It'll likely work as long as the t-con is the same and all the connectors are the same.

[gijoey198079]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

Testing some of the voltage regulators on the board, can't find exact data sheet for some so any help is great. Below is the regulators with what the reading is.

AZ7805T-E1 @ U3
1. 11.56v
2. 0v
3. 4.83v

AMC1117 @ U4
1. .83v
2. 3.21v
3. 4.93v

AMC1117 @ U8
1. .88v
2. 3.16v
3. 4.96v

AMC1117 @ U33
1. .81v (screen flickers for a second when i touch this pin with probe)
2. 3.18v
3. 4.93v

AMC1117 @ U7
1. .02v
2. 1.23v
3. 3.17v

K1117S15 @ U 9
1. 0v
2. 1.46v
3. 3.18v

AMC1117 @ U2
1. .91v
2. 2.24v
3. 4.95v

1084 @ U10
1. .67v
2. 2.53v
3. 4.93v

This is all of the 3 pin voltage regulators, I'm still not real clear on how to test the 4+ pin ones. By my calculating all of these are bad, 1 is close to range. Is that normal for it to be that bad but screen still look good on certain inputs?

[gijoey198079]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

First pic is on AVI using DVD player, 2nd pic is cable, big difference.

[budm]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

U4, U8, U33 look bad.
The output at pin 2 should be equal to reading on pin 1 + 1.25 = pin2 output.
I.E. PIN 1 is 0.25v, then pin 2 should be 0.25 + 1.25 = 1.5v.
u2 is a tad above 2% spec.
Please see link at the bottom of my signature to learn more.
Please also check your meter's batteries to make sure it is good.

[retiredcaps]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

U4, U8, U33 look bad.

Please also check your meter's batteries to make sure it is good.

Hmm, I can't recall 3 voltage regulators all going bad on one board.

The battery in the multimeter seem to work because U9 reads 1.46 on a 1.5V regulator?

However, the regulars know all too well that at least once a week, we get led on a wild goose chase due to batteries on the multimeter being weak/bad, but there is no "low battery" indication on the multimeter lcd screen.

[tom66]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

A possibility is whatever is feeding those three regulators is excessively noisy or oscillating. This would also cause the video noise issue.

[budm]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

That can be bad filter caps before and after the LDO and cause Osc like TOM said.
It will be easy to parallel another cap at pin 2 of the LDO to find out.

[gijoey198079]

Re: Vizio VX37L HDTV10A Works perfect except AVI video is distorted

I changed batteries in the multimeter but readings were only .01-.04 difference in the first time, i ended up just using the spare board i had here and already got it sold.

Thanks all for the help.