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Old 08-29-2011, 06:52 PM   #1
MattC
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Default Vizio P42HDTV10A: no picture, no sound

I've done a bunch of forum reading and have a similar story as often posted: I got a Vizio model P42HDTV10A 42" plasma for free from a friend. No picture (either from any source or a startup screen) and no sound. TV has an orange led when on standby, turns green when powered on. Can not be turned off other than by pulling the power cord.

I can solder, desolder, can read a circuit diagram and work a multi meter so I thought I'd make a project out of getting it to work. That being said, this is my first experience inside a TV. Hopefully with all your help I can get it going again, or at least determine its worth more as a dumpster filler than as an actual TV.

I have a few extra boards that came with it. I have downloaded the service manual (though some pages are missing) and done the following things so far:

-Visually looked for bad caps. I don't see any, but again, I'm new at this.

-Turn TV on, hear relay click.

-Tested power in to the main and sub power boards, 118v. Seems good.

-The sub power board outputs 5v and 12v to the main board, again seems as it should.

-The main power board has some funkier outputs. The output values as printed on the board are shown in the pic below.

http://www.jerseylooker.com/random/B...e/IMG_0740.jpg

For readings from the output of the main power board I get:

To the main video input board:
RLY ON - 6.1v
Vs ON - 6.1v

To the X and Y sus boards:
+5v: 10.4v
Va: 151.5v
Vs: 410v

The outputs to the X and Y boards are about twice what they should be. What should I look at/for next? I can provide pictures of anything needed. Some preliminary ones of the main power board below:

http://www.jerseylooker.com/random/B...e/IMG_0741.jpg
http://www.jerseylooker.com/random/B...e/IMG_0742.jpg
http://www.jerseylooker.com/random/B...e/IMG_0743.jpg
http://www.jerseylooker.com/random/B...e/IMG_0744.jpg
http://www.jerseylooker.com/random/B...e/IMG_0745.jpg
http://www.jerseylooker.com/random/B...e/IMG_0746.jpg
http://www.jerseylooker.com/random/B...e/IMG_0747.jpg

I appreciate any and all help. Thanks!
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Old 08-29-2011, 07:37 PM   #2
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Default Re: Vizio P42HDTV10A: no picture, no sound

Let's cover the basics.

1. For a number of reasons pictures should be hosted on this site. Use 'Manage Attachments' - below the text entry area. I suggest a minimum of 1000 x 1000 pixels. The site limit is 2000 pixels in either dimention.

2. Quality is more important than quality. Let's start with only three pictures. One should be an over-all shot of the back of the TV (cover removed, of course), the second a similar shot covering the power supply, and the third a single shot of the 'main board' - the board with the input connectors.

3. Detail is important - we can get a log of information from a sharp, well lit picture from directly overhead. A blurry one shot under dim light doesn't do much good (neither does a reflection of the camera flash covering a large part of the board).

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Old 08-29-2011, 08:33 PM   #3
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Default Re: Vizio P42HDTV10A: no picture, no sound

You know, in all the forums I frequently post on, it drives me nuts when people don't use the forum to host pictures for threads; so I have no Idea why I didn't do that here! Sorry!

In any case, attached are 3 pics. If they are not good enough, let me know.
Attached Images
File Type: jpg OverallView.JPG (565.0 KB, 81 views)
File Type: jpg MainPower.JPG (535.2 KB, 70 views)
File Type: jpg MainVideoInput.JPG (703.1 KB, 58 views)
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Old 08-29-2011, 10:05 PM   #4
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Default Re: Vizio P42HDTV10A: no picture, no sound

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Originally Posted by MattC View Post
You know, in all the forums I frequently post on, it drives me nuts when people don't use the forum to host pictures for threads; so I have no Idea why I didn't do that here! Sorry!

In any case, attached are 3 pics. If they are not good enough, let me know.
I, on the other hand, never make a mistake.

OK, I'll be serious. First of all, this is based on an LG panel. The sustains are notorious for shorted hybrids. However, the symptoms are not consistent with that problem. Let's try one thing. Black / blue / red cables run from the upper left corner of the power supply to the sustain boards. Disconnect them, then see if the TV can be turned on and off with the power button.

Next, on the back of the plasma panel is a white label with the voltages the panel requires listed. Still with the cables disconnected, check those voltages. A quick alignment guide for the panel can be found here.

I am REALLY concerned about the unusual voltages you are seeing. What did you use as the ground point?

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Old 08-29-2011, 11:20 PM   #5
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Default Re: Vizio P42HDTV10A: no picture, no sound

PlainBIll, thanks for your replies!

I'm using board mounting screw heads as ground points. Generally either the one on the bottom middle of the main power board, or the one below that, that only holds down a ground wire. I try other random ones as well to confirm my readings.

Also, I ran to the shop and got my decent meter instead of the crappy harbor freight one I keep at home. I think it may be busted or I was on some wrong setting when I tested prior.

I pulled all three connectors in the upper left that go to the sus boards (but did not disconnect the one in the lower left that goes to the main board). I can again turn on the TV (have the green led on front come on anyway) but still can not turn it off.

Below is the panel voltage sticker (not hi-res, guessing its ok for this one). With the cables still disconnected, and after alignment I get 60v and 186v coming out of the main board. Seems good there. If I connect the Y and X boards, I get nothing out of the main power board (the relay clicks as if turning off). If I connect just the X board, I get the proper 60v and 186v out of the main board, and the proper 100v on the Xsus board (after alignment). So, I'm thinking something funky with the Ysus?
Attached Images
File Type: jpg IMG_0787.jpg (374.2 KB, 49 views)

Last edited by MattC; 08-29-2011 at 11:22 PM..
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Old 08-30-2011, 07:28 AM   #6
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Default Re: Vizio P42HDTV10A: no picture, no sound

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Originally Posted by MattC View Post
PlainBIll, thanks for your replies!

I'm using board mounting screw heads as ground points. Generally either the one on the bottom middle of the main power board, or the one below that, that only holds down a ground wire. I try other random ones as well to confirm my readings.

Also, I ran to the shop and got my decent meter instead of the crappy harbor freight one I keep at home. I think it may be busted or I was on some wrong setting when I tested prior.

I pulled all three connectors in the upper left that go to the sus boards (but did not disconnect the one in the lower left that goes to the main board). I can again turn on the TV (have the green led on front come on anyway) but still can not turn it off.

Below is the panel voltage sticker (not hi-res, guessing its ok for this one). With the cables still disconnected, and after alignment I get 60v and 186v coming out of the main board. Seems good there. If I connect the Y and X boards, I get nothing out of the main power board (the relay clicks as if turning off). If I connect just the X board, I get the proper 60v and 186v out of the main board, and the proper 100v on the Xsus board (after alignment). So, I'm thinking something funky with the Ysus?
Good work. Yes, the problem is the Y-sustain, and probably the hybrid (under the large heat sink).

Here's the problem - I have a fair amount of experience with this panel. Replacing the Y sustain is a pain, but doable. Replacing the hybrid is a major task. On an LG TV you would have one of two possible problems - either the TV would shut down by itself, or you would have a 'sound with no picture' problem.

Some models of Vizio main boards have the 'turns on, but won't turn off' problem; that is a bad U33; I don't see a U33 on this board. And that leads to the fact that unrelated failures on different boards is very unusual.

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Old 08-30-2011, 07:54 AM   #7
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Default Re: Vizio P42HDTV10A: no picture, no sound

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Originally Posted by PlainBill View Post
Good work. Yes, the problem is the Y-sustain, and probably the hybrid (under the large heat sink).

Here's the problem - I have a fair amount of experience with this panel. Replacing the Y sustain is a pain, but doable. Replacing the hybrid is a major task. On an LG TV you would have one of two possible problems - either the TV would shut down by itself, or you would have a 'sound with no picture' problem.
So then tonight, out comes the Ysus board! Looks like online/eBay replacements are not terribly expensive for a full board. My soldering skills are average, so I'd probably cook the board trying to replace the hybrid.

Quote:
Originally Posted by PlainBill View Post
Some models of Vizio main boards have the 'turns on, but won't turn off' problem; that is a bad U33; I don't see a U33 on this board. And that leads to the fact that unrelated failures on different boards is very unusual.
Yea, I saw U33 mentioned in some other threads. I couldn't find it either. Worst case, if the main was bad too, I have an extra for this thing I can swap in.

Stay tuned, I'll let you know how things go with the Ysus.

Last edited by MattC; 08-30-2011 at 08:51 AM..
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Old 09-10-2011, 12:20 PM   #8
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Default Re: Vizio P42HDTV10A: no picture, no sound

Update: So I got and installed a rebuilt Ysus board from Coppell TV Repair in Texas via eBay. I installed it and have both X and Y boards hooked up and getting proper voltage to them from the power board. Seems all is now well there.

I still get the proper 100v out of the XSus board.

On the Ysus board the output voltages are off. A) I can't reach the proper output voltages (Vy = 200 and VSC = 125), even with the adjusters turned all the way up, and B) the output voltages constantly change by up to 20v. I have firm contact with my VOM leads, so I don't think its that; but maybe it is. So, what should I be looking at next?

In addition, here is the status of what happens when I now turn on the TV. I plug in the TV (but do not yet hit the power button) and the led on the front of the TV turns orange, a relay clicks and the screen lights up white. Then, when I click the power button, the led on the front of the TV turns green and the screen turns a different shade of white. No sound or video comes through when I connect a DVD player and scroll through the inputs and I can't turn the TV off by the power button.
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Old 09-12-2011, 06:21 PM   #9
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Default Re: Vizio P42HDTV10A: no picture, no sound

Did a little more testing and noticed I get power out of the main power board to the x and y sus boards regardless of if I hit the power button on or not (ie front led is green or orange). Is that right?

if i tmeans anything, with all output wires disconnected form the y sus board (including the y buffer board) the Vsc output is 5v and the Vy is 16.
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Old 09-14-2011, 11:44 AM   #10
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Default Re: Vizio P42HDTV10A: no picture, no sound

So I think I'm largely good to go. I was measuring the Ysus outputs wrong, one pole to ground instead of across the resistors. (told you I was a beginner!) So, now I have a clear picture, TV turns on and off at will and everything generally works. I didn't have an oscilloscope to measure the waveforms but instead tuned them in to where the TV looked clearest. Maybe I'll borrow one to do it right, but for now, seems everything works.

I still have one issue I mentioned above.

In addition, here is the status of what happens when I now turn on the TV. I plug in the TV (but do not yet hit the power button) and the led on the front of the TV turns orange, a relay clicks and the screen slightly lights up . Then, when I click the power button, the led on the front of the TV turns green and the screen turns on as normal. Essentially I get power to the X and Y boards when the TV is plugged regardless of if it is turned on or not. Is that the way it should be? I'm thinking not and that a relay on the main power board isn't working properly..
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Old 09-14-2011, 02:55 PM   #11
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Default Re: Vizio P42HDTV10A: no picture, no sound

Quote:
Originally Posted by MattC View Post
So I think I'm largely good to go. I was measuring the Ysus outputs wrong, one pole to ground instead of across the resistors. (told you I was a beginner!) So, now I have a clear picture, TV turns on and off at will and everything generally works. I didn't have an oscilloscope to measure the waveforms but instead tuned them in to where the TV looked clearest. Maybe I'll borrow one to do it right, but for now, seems everything works.

I still have one issue I mentioned above.

In addition, here is the status of what happens when I now turn on the TV. I plug in the TV (but do not yet hit the power button) and the led on the front of the TV turns orange, a relay clicks and the screen slightly lights up . Then, when I click the power button, the led on the front of the TV turns green and the screen turns on as normal. Essentially I get power to the X and Y boards when the TV is plugged regardless of if it is turned on or not. Is that the way it should be? I'm thinking not and that a relay on the main power board isn't working properly..
How much voltage are you getting to the X and Y boards? It's not impossible the boards get 5v_SB

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Old 09-14-2011, 06:13 PM   #12
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Default Re: Vizio P42HDTV10A: no picture, no sound

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How much voltage are you getting to the X and Y boards? It's not impossible the boards get 5v_SB

PlainBill
They are getting the proper voltage as if the power button was on - 186v and 60v.
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Old 09-14-2011, 07:22 PM   #13
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Default Re: Vizio P42HDTV10A: no picture, no sound

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They are getting the proper voltage as if the power button was on - 186v and 60v.
Now, I've never checked that, but I think you are right; something is amiss. Other than your idea of a stuck relay, the only possibility I can think of is some sort of 'instant on' feature. It would be interesting to check the power draw from the AC line while this is occurring (for example, using a Kill-A Watt). If it was less than 50 watts, I'd take the 'instant on' idea seriously. If it was over that, especially over 100 watts, it is definitely a defect.

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Old 09-15-2011, 05:12 PM   #14
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Default Re: Vizio P42HDTV10A: no picture, no sound

There is a switch on the main power board labeled AUTO/NORMAL. It was switched to AUTO. I switched it to NORMAL and all is well. Everything now works as it should. I have 3v or so going to the sus boards when plugged in and the power off; and no light up of the screen. Perfect.

TV shuts itself off when I try to use the DTV tuner, but I have another tuner board I can swap in, or I'll just leave it as is. I don't plan to ever use the tuner and all the other inputs work fine; so we'll see.

Thanks for all your help!
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Old 11-18-2013, 08:19 PM   #15
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Default Re: Vizio P42HDTV10A: no picture, no sound

Bringing this thread back from the dead. I've finally decided (after 2 years!) to dig into this TV to see why the DTV tuner does not work.

I've been using the Cable, RGB and Composite inputs for years with no issues. Picture and sound all work for those. However, the TV does not seem to recognize the Digital Tuner. If I pick DTV as an input, it does not even bring up an icon to scan for channels, and ultimately will just turn itself off from "no input". I have spare DTV and Main AV boards that I have swapped in with no change in outcome. (Boards were said to work, but who knows)

What would be the next (first) order in troubleshooting?

Thanks!
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Old 01-16-2014, 10:06 PM   #16
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Default Re: Vizio P42HDTV10A: no picture, no sound

Did you figure out anything on this yet? Did you ever see the message.. "Going into deep sleep"? That's a message I got when there was no input present. I've got a couple of DTV cards that also don't have the DTV menu and one that just makes a blank screen. I had a good one that when I put that in the set, it works fine.
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Old 01-23-2014, 10:57 AM   #17
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Default Re: Vizio P42HDTV10A: no picture, no sound

i have the same tv (p42hdtva10) her are some pics ! i went to the manual and check all voltages -vy -200 , vsc 120 also va60v vs 184v
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File Type: jpg 029.JPG (1.15 MB, 13 views)
File Type: jpg 028.JPG (301.8 KB, 10 views)
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Old 03-03-2014, 04:57 PM   #18
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Default Re: Vizio P42HDTV10A: no picture, no sound

That looks like the Zsus board.. (the one to the right of the Power supply as you're looking at the back of the set. I know when I unplug power to the Zsus.. the picture looks dim and distorted like that.
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Old 03-04-2014, 09:31 AM   #19
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Default Re: Vizio P42HDTV10A: no picture, no sound

The when I unplug z-sus screen goes black ?
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