Plasma TV Vizio p42hdtv10a

[Xiaodan2009]

I just picked up a Vizio p42hdtv10a, the tv will power on and play near perfectly for about 10 minutes, the only imperfection is a couple of nearly unnoticeable randomly scattered red pixels that move around in real time. After 10 minutes or so the tv will start having more issues, the screen will start flickering on and off very frequently, and eventually there will be so many pixels you can hardly see anything on the screen. Once it gets to that point it takes approximately 2 minutes until the tv powers itself down.

After it powers itself down, if you try turn the tv back on it will only stay on for 30 seconds or so and power back down.

One thing I noticed about it was that while the screen is flickering you can hear a slight kind of stuttering sound coming from the power supply, like it is taking alot of extra stress and cant keep up (imagine a car running out of gas, and sputtering trying to get those last few fumes.)

I've opened the tv up and took a quick visual inspection of all the capacitors, i did not notice any that were bulging, that is not to say that none of them are bad though.

I have a multimeter and I would be able to test some things, I have done circuit board soldering a few times before, but this tv has me stumped as where to look next.

My experience with circuit boards is honestly not very good, but I am also pretty persistent and don't normally give up to easily so if I could get guided in the right direction im sure I could get this fixed.

[PlainBill]

Re: Plasma TV Vizio p42hdtv10a

One theory is the TV is warning you the Y-buffers are about to blow. The suggestion is to replace both upper and lower Y buffers before they damage the Y-sustain.

I have not verified this myself, so feel free to take it with a grain of salt.


PlainBill.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

I dug into this a little bit more, i took the tv apart again, the humming/stuttering noise that I was talking about is coming from the IC on the Y-sus board, I used a multimeter on the cables coming from the power supply.

5v reads 5.1v
VS reads 188v
Va reads 60.2v

I was able to eliminate the humming noise on power up by disconnecting the y-sus board, and only leaving the z-sus board connected. If i had just the y-sus board connected the humming would start again.

In my opinion the IC is bad, but I personally have no experience in this, the other question that I would have is if my IC went bad what would have caused it? If the IC is bad would it damage anything downline from it?

Back to the Y-buffer, I have absolutely no clue what the purpose of it is, I don't have any good understanding of what makes a plasma TV run, so here are my observations, let me know what you think and if you have an idea of where to go to next at this point.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

One more update, I just tested the two fuses on the y-sus board and they both test good for continuity.

At this point would it be worth buying this? http://cgi.ebay.com/VIZIO-VP42-HDTV-...item5d2e2dfb4b
Is there a way to test if the Y-buffer is causing the issue? At the moment I have the y-sus board pulled from the tv.

[retiredcaps]

Re: Plasma TV Vizio p42hdtv10a

Back to the Y-buffer, I have absolutely no clue what the purpose of it is,

http://blog.coppelltvrepair.com/

has excellent info. Check their archives for how to test them.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

Thank you very much for that link The test on the main page just answered my question, the IC is definetly bad.

I just ordered an IC, would it be a good idea to order up the Y-Buffer board as well (i havent had a chance to go through and test it yet, its time to goto bed, work in the morning) any other components I should try test?

Also, I'm looking for a good soldering/desoldering setup at a reasonable price if anyone has any recommendations, lately i've been using a $20 soldering iron that I bought at radio shack 10 years ago.

(picture added)

[rayrod81]

Re: Plasma TV Vizio p42hdtv10a

You will want to test the mosfets that are in circuit with the IPM. These will sometimes also short out when IPM goes bad. You will need to test after you remove the IPM. Also just for your information it may take you up to an hour or longer to remove the IPM. It is soldered on both sides and if you are not careful then the tracks can be broken and the solder pads and contacts can be pulled right out of the board. Patience is key with these.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

Alright, I finally had time to work on the tv again, I got the IC out cleanly I just tested the mosfets without the IC in place and they tested at 1.86m Ohm one way, and 2.31 the opposite way without the ic in. With the IC in (unsoldered) they were reading 1.94 and 5.01 I take it that means they are good?

[rayrod81]

Re: Plasma TV Vizio p42hdtv10a

Yes if they were bad they would read as a short.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

I soldered on the new IC and put the board back in, the tv will stay on with a good picture it just has a little bit of red snow on the screen, and after 10 seconds or so the TV shuts itself off apparantly as some sort of safety feature. I am leaning towards it needing a buffer board, I am planning on ordering one tomorrow, does anyone have an opinion if this is the right thing to do?

I only started the tv once to see what would happen so i'm pretty sure it didn't damage my IC in that short of a time.

[rayrod81]

Re: Plasma TV Vizio p42hdtv10a

This will happen on these TVs if the voltages coming off the power supply are out of spec. Check Vs and Va and make sure they close to what the voltage label on the panel says. The red speckles in the picture are actually a problem with the control board. Many times after a Y-sus and Z-sus are replaced or fixed the firmware of the control board needs an update to get rid of the red speckles in the picture.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

Well apparantly there's another issue, I did some testing and the power supply is at the point where it wont even power on with the ysus and the zsus disconnected. With the tv turned off the voltage readings im getting are just jumping back and forth from 0 to 1 volts over and over again.

[Xiaodan2009]

Re: Plasma TV Vizio p42hdtv10a

Oh and also the orange light on the front stays lit, and when you press the power button the light will turn green for a moment and than flash back to orange, it does this whether i have just the ysus, just the zsus, both boards or no boards connected.

Here's some pictures of the power supply

[daimoku]

Re: Plasma TV Vizio p42hdtv10a

If you don't already have this, the troubleshooting section might help you identify the fault: service manual here.

[mvalent000]

Re: Plasma TV Vizio p42hdtv10a

The tail end of your dilema is where I was when I picked up my 50" Vizio. It would turn on then turn itself off.....I just had it sent out and rebuilt by a company in Texas. Plugged it in when I got it back and it's fine.
So you might be at the point where the power board will have to be replaced or rebuilt.
It just so happens that now I have red snow for the first 3 minutes that the tv is turned on then it goes away.

[splitcrete]

Re: Plasma TV Vizio p42hdtv10a

Oh and also the orange light on the front stays lit, and when you press the power button the light will turn green for a moment and than flash back to orange, it does this whether i have just the ysus, just the zsus, both boards or no boards connected.

Here's some pictures of the power supply

Did you check the two big caps between the heat sinks ?They look rounded on top.