Vizio P50HDTV10A Sound No Pix

[dfergy54]

On The Chassis it syas it is an LG PDP50X4TA35

I have a vizio 50 that powers on fine , I can change inputs sources and that works as well as the sound.
There is one pixel line all the way across the top that has video.
Very fine line almost un noticeable.

Looked very closely at the PSU and Ysus and Zsus for any bulging caps and find none.

Checked Va and VS voltages they are right on the money.
Checked low voltages on edge connectors Plus 5 , 15 volts and 3.3 volts all good w minimal ripple.

The only clues I am getting are the LEDS on the Main logic.
On Power on D1 and D2 are off d3 thru d5 are on.
Upon power off I get, on the front power light 10 green flashes.

All heat sinks on every board are nice and warm after 30 minutes turned on. The warmest on the Ysus black heat sink 102 degrees F.

Upon power up the screen brightens a bit but the only video displayed is the very top row of the screen and it does fluctuate with the source video content.

I have checked every fuse I can find including the surface mount fuses.
This one has me stumped a bit.

Any Ideas anyone?

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

Try disconnecting your buffer boards one at a time. If I remember correctly, the same model I worked on awhile back that showed 10 blinks had a bad Y-Sus.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

Uploading Pix of back of tv for reference.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

The buffer boards on the left side are daisy chained , I could only disconnect the bottom board, the cable goes into the top board then has a really short jumper cable to the bottom board, So I couldn,t try it with just the bottom board connected.

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

I'd check the -Vy and Vscan voltages on the Y-Sus to see if they match the panel label specs. I think -Vy should be something like -130V and Vscan should be around 120V. My memory may not be accurate. I've included pics of the Y-Sus and Z-Sus voltage test points.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

VA=60 VS=193 as per label.

Ysus R85 Left side = -139. right side = -177.5
C14 reads 129.7 across.

Zsus Q53 Tab Reads 100 volts Left leg reads 62 Volts Right Leg reads 70 volts.

I have a Tektronix scope if needed.

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

Hmm, it looks like your voltages are ok, although the -Vy seems a little out of line. It wouldn't hurt to check waveforms. There should be an orange test point labeled "Set_dn" on the Y-Sus. It's near the lower buffer.

I believe you can do these tests on the buffers:

- Place your leads on 1 and 2 in the buffer picture, respectively, then swap them. You should see something like 0.67V in one direction and "OL" in the opposite direction.

- Place your negative lead on 1 in the buffer picture then run your positive lead along the pins at the ribbon connectors to look for shorted chips.

If things check out, you may be looking at a main board or logic board issue.

[hienton2]

Re: Vizio P50HDTV10A Sound No Pix

I am sorry with dfergy54. I have quick question with Capkid : I have same issue
My tv has the R54 ,R55 (5 watt)on Y sus board burn open I think these resistors are fuse of VS for small IPM .
I think The small IPM is bad . I aready changed This with a new IPM. But my tv still has no prime. And TV has no -vy . TV has vscan 139v. How can I restore -VY. Thanks

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

I am sorry with dfergy54. I have quick question with Capkid : I have same issue
My tv has the R54 ,R55 (5 watt)on Y sus board burn open I think these resistors are fuse of VS for small IPM .
I think The small IPM is bad . I aready changed This with a new IPM. But my tv still has no prime. And TV has no -vy . TV has vscan 139v. How can I restore -VY. Thanks

I'll go over to your thread.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

The peak on set up was low 220 volts adjusted to 292 per spec.
The set dn timing was off by 4 us, adjusted that as well.

On the buffers I checked across the two points and showed 67 volts ea way
Did you mean to ohm it out because your post said .67v one way and overload the other? Ohmed it out @ 1.87 Meg each way approx.

Powered down and checked all the ribbon edges against buffer 1 in your picture got 4 to 12 meg as I ran down the edge connector slowly.

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

The peak on set up was low 220 volts adjusted to 292 per spec.
The set dn timing was off by 4 us, adjusted that as well.

On the buffers I checked across the two points and showed 67 volts ea way
Did you mean to ohm it out because your post said .67v one way and overload the other? Ohmed it out @ 1.87 Meg each way approx.

Powered down and checked all the ribbon edges against buffer 1 in your picture got 4 to 12 meg as I ran down the edge connector slowly.

Sorry, I wasn't clear. I tested the buffers out of the TV in diode mode on my meter.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

Checking the buffer point one to point two, in diode test mode i get .461, negative lead to one and OL when I check with pos lead to point 1.

I was thinking originally it was either the I/O Board or the Processor ? (the board that has physical connections to the Ysus).

It,s like the addressing Info are not getting to the buffer boards except on the very first line at the top of the screen.

The Board ERB35959201 is the board with the status LED,s on it.
Do you have any info on this board for regulators and voltages?
As well as the input / IO board.
I,m thinking the IO formats the video digitaly then passes it to the smaller interconnect board which maybe personalizes it for this display?

Whew this all makes me wish I just had bad caps He he.
Pix Attached

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

Here's some info I have on troubleshooting the control board in a 50PC1DR plasma; it should be mostly relevant to the Vizio. I've also included a block diagram for the 50PC5D, whose chassis I believe is identical to the Vizio. I don't see anything specific to troubleshooting the main board.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

The diagrams are similar but not close at all on the logic EBR35959201 board or the IO Board 3850-0132-0150(3E). This board does not include the tuner it is a spearate board.

Not sure that is where the problem originates anyway, on my logic instead of the pattern generator being a pin short on p1, it is an external pattern generator of some sort.

Regards
David

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

I just noticed the connections on the bottom in the block diagram, I thought the heat sinks along the bottom were part of the audio amplifier, but I,m thinking they are like the left hand buffers but on the bottom maybe supplying addressing verticaly ?

Anybody know what these are for sure?


This stuff runs on smoke...... Cuz when the smoke goes out it dosen,t work anymore.

Just kidding, no smoke yet!

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

Just disconnected one of the bottom boards and I lost a third of the top line that was being displayed correctly.

Rechecked the bottom buffer board and looked a little closer at the screen, No picture still but I have noise lines coming and going on the bottom half of the screen.

I have removed the Ysus and measuerd the only FET I can get to and it shows shorted, Maybe the chip is making it look like it,s shorted.

The only way to find out is to remove the IPM.
Does the ER IPM drive the SUS IPM . Or should they both be replaced if one is replaced?
If so can you give me guestimate of the pair from mouser or MCM?

Thanks for your patience.

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

Yes, the bottom address boards are for addressing vertically. Some TVs have address boards at the top and bottom of the panel.

Anytime I've repaired one of these TVs, I've change both IPMs. I even change out the IPMs on the Z-Sus at the same time, since they could fail shortly thereafter - your call. I've used MCM, CoppellTVRepair on eBay, slp5188 on eBay, and startboy1010 on eBay numerous times. The last time I purchased an IPM, it was $40. The part numbers are normally on the side of each of the heat sinks (not always), then you should be able to find a proper substitute based on the part number. Your Y-Sus seems to be working correctly, though, based on your test results.

Edit: I believe these are the IPMs for your Y-Sus, but please confirm: STK795-844 and STK795-842A. If so, Coppell has them for less than $25 ea.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

I agree , I can,t really put my finger on the YSUS , but it seems to be the most common failure. Without a real schematic and troubleshooting tecnique on this type problem I may have jumped to that conclusion. But I wanted to pull the board and physically inspect the IPM,s for evidence of failure.

I really found no compelling evidence, I saw the FET or tab transistor under the heat sink and measured a short on the two outside leads, source to drain???

Hate to be demoted to glorified board swapper but that seems to be where the mfg has pushed me. Wirh no real circuit info and my lack of knowledge on these circuits.

This TV was shipped from Colorado to oklahoma and has not worked since. No apparent trauma to the set. I have another Vizio 50 plasma sitting right behind this one that I use everyday but it is a 20A and parts are incompatable I believe.

I would sure hate to take that one and make it broken by dinking around with it.
Are there any waveforms available for the Buffer boards?
Any timing checks other than set up and down?

Still my best guess is logic or physical screen failure, but I have no way to prove or disprove the theory other than board swap which is not particularly economical.

I really don,t have a place to focus on this tv yet. A little frustrating , but I have patience so I will get there eventually.

It will all make sense when I figure it out.
These TV,s sure look great compared to the old rastor scan sets.

[capkid]

Re: Vizio P50HDTV10A Sound No Pix

The service manual is here. I didn't find it particularly useful in my case: http://www.toms-service-manuals.com/...&Search=Submit

I wouldn't mess with your working TV - been there and done that, and I ended up with two non-working TVs and had to start all over. Also, I believe the parts in the 20A and 10A are different. You could try carefully pulling the IPMs or maybe try changing out the control board first, since they're only about $20 shipped on eBay.

Edit: Ok, wait...was the TV confirmed as working just before it was shipped? If so, and all your connectors are properly seated, you might have a panel issue. The TV may have been damaged in shipping.

[dfergy54]

Re: Vizio P50HDTV10A Sound No Pix

By control board do you mean the I/O or the smaller board that feeds all the buffers.

There is a possibility the panel has issues, but it is externally physically pristine, as best as I can tell. Worked perfectly before the movers packed it up for the guy I bought it from.

Put it all back together today and was hopeing for a cable reseat miracle but alas, no Joy.

Looking closely at the Zsus it seems the ribbon is a single conductor.
The bottom buffers are low voltage Data/addressing
The ysus passes high voltage data to the side buffers.

I think I,ll remove the front Bezel and see if I can observe any damage with the ribbons to display, But the single line at the top of good video is really strange.

I,ll repost what I find.