Another vizio vx42l

[bigdozer]

I was given a vizio vx42l. Manufacture date of Nov 2007. Owner said it was victim of a power surge. Got it home and plugged it up and the vizio logo turns on in amber or orange color. Push power and it turns white. No backlights or sound. Took back off and inspected. Dont see anything burnt, swollen or fried. After reading tons of posts on these models I unplugged the tcon board from main board and the backlights come on. Hooked up vcr and have sound. Buttons on tv do turn it on and off. Remote works also. Thinking it needs a new tcon board. I do have a dmm. Any help would be appreciated. Tried uploading pics but it says security token missing. Then deleted my entire first message. Waiting on reply from administrators. Ill try one overall pic.

[bigdozer]

Re: Another vizio vx42l

Ok it works. I can post pics of certain baoards if needed. Also the inverter board is different than any i've seen posted. Master and slave in one?

[rmoody]

Re: Another vizio vx42l

typically with a bad tcon you still have backlights and sound just scrambled or no image. Could have multiple boards fried from the power surge. Tcon should have a picofuse labeled F1, check it for continuity.

[bigdozer]

Re: Another vizio vx42l

I checked f1 with meter and it beeps. Is there another way to test one? When i plug the tcon up i get no backlight or sound.

[rmoody]

Re: Another vizio vx42l

well it would be the cheapest board to replace so if you want to try replacing it, go for it. maybe somethings shorted in it and when it's plugged into the main board it causes problems there too. Wouldn't be surprised if you had a problem with the Main board too but hopefully not.

[bigdozer]

Re: Another vizio vx42l

I'll keep looking for a wii victim. I have 3 lcds tvs i've been tinkering with. This one seemed to be the easier fix.

[edtv]

Re: Another vizio vx42l

Did you replace the tcon board yet? Did it fix your problem? I have a VX42L that I suspect it has a bad Tcon. I already replaced the power and main but when I power it on I get color test patterns on the screen that change to a full screen different color every 5 seconds...It's weird....

[bigdozer]

Re: Another vizio vx42l

I haven't found a board for it yet. I did swap out the main board for one i know works and it didnt work. I'm sure its the tcon.

Did you replace the main board with the exact same board? Through my "googling" ive found that you have to go by the serial numbers to get the correct boards. Or match the part number on the board. I'm sure you did but just checking. Maybe yours is stuck in some kind of test mode. Maybe a firmware update?

[rmoody]

Re: Another vizio vx42l

Did you replace the tcon board yet? Did it fix your problem? I have a VX42L that I suspect it has a bad Tcon. I already replaced the power and main but when I power it on I get color test patterns on the screen that change to a full screen different color every 5 seconds...It's weird....

Ed, Im 98% positive a new tcon will fix your problem, I had the brother/sister model of this tv the vw42l with the exact problem, tried main and power board and had about given up when I tried the Tcon. The fuse on my Tcon was still good but something was wrong on it and it threw up the color bars. Mine didn't change colors like yours but it had them up there like the emergence broadcast service test.

[rmoody]

Re: Another vizio vx42l

$19 bucks if it looks like yours
http://www.ebay.com/itm/VIZIO-VX42L-...item27be942175

[bigdozer]

Re: Another vizio vx42l

Update!

So i didn't want to just give up and order a new tcon for this tv. So i followed kingofcoins troubleshooting and measuring of ldo regulators "brother mikes tv". I've came to the conclusion that i need to replace U7 and U33. My measurements of these regulators match exactly what he measured on page 4 post 68.

Luckily i have all the boards from a vx37l that i salvaged from a cracked screen that i've seen working. Even after the panel was damaged you could make out the "no signal" moving across the screen. The main board has all of the regulators i need. I need to order some "quik chip" and practice on a old laptop board before i attempt scavenging anything.

I did find if i unplug the 2 connectors on the top left side of the tcon and power up the tv that half the screen will come on and display picture and audio. Reversing this and unplugging the top right 2 does not show picture or sound.

So i'm thinking that maybe the regulators aren't outputting the correct voltages to properly fire up the tcon to full power and by unplugging certain cables it's just enough for half the screen.

If anyone has any other ideas on trouble shooting this while i wait on some quik chip your input would be greatly appreciated.

[BlkSmth]

Re: Another vizio vx42l

1) vx42l off ebay that had vertical lines moving around during warm-up/forever that changed to large bars/blocks... typical Vizio logo issue; no power off; nothing...etc.... similar to this : http://www.colombospace.com/Youtube/7PE4rRXxcpI

2) 1 hours disassembly/assy troubleshooting with my friends here on BADCAPS
3) 2 x to stop the shakes during replacing U33 since it was 2.06
u2 pin2 = 3.29
u7 pin2 = .98
u8 pin2 = 3.28
u9 pin2 = 1.16
u33 pin2 = 2.06 <---------- again feeds u7/u9

4) I got lucky.... I had a donor part laying around to swap into u33 (what a dam pain in the " @ " to salavage while desoldering)

5) 42" tv for $102.50 <---- Including shpping


as always everyone, thanks for the great posts! - BlkSmth

[bbjunkie]

Re: Another vizio vx42l

4) I got lucky.... I had a donor part laying around to swap into u33 (what a dam pain in the " @ " to salavage while desoldering)

While it may not be the correct way to do it, I saw a video on youtube not long back where the guy instead of removing the solder, built up the amount of solder on the legs (and especially the tab). The reason he stated was to give a larger thermal mass, thus making it easier to get the solder melted on all pins at once.

This obviously can make a real mess if done on some components, but seemed to work well on a tiny 3 legged transistor/regulator.

Need to remember not too much heat though, or the traces may lift.

Good score on the TV, and congratulations on keeping another out of landfill.

Jim

[retiredcaps]

Re: Another vizio vx42l

I saw a video on youtube not long back where the guy instead of removing the solder, built up the amount of solder on the legs (and especially the tab).

Probably eevblog part 2 or 3 of the soldering tutorial at

http://www.eevblog.com/episodes/

[BlkSmth]

Re: Another vizio vx42l

Dropping additional solder was indeed what I did for heat mass (I'm surprised the chip still worked after the amount of heat and attempts it took with additional help from my micro flat blade)
I then used my solder braid to clean it up while lifting the chip slowly.... You are correct about the traces on the board.
One managed to lift, just didn't tear.

Decent picture like the vx32l taken down to put this one up. Now to figure out what to do with the good vx32l

[bigdozer]

Re: Another vizio vx42l

I did manage to get one chip off by adding extra solder but i'm not gonna solder it onto the other board not knowing if i fried it with the extra heat. How can you measure one of these out of circuit?

[Scenic]

Re: Another vizio vx42l

You could just tack it in with short wires for testing, before soldering it in normally.
I've done that a couple times before..