Vizio P50HDM no display or sound

[tom66]

Re: Vizio P50HDM no display or sound

I don't know what the average voltage you see should be. The problem is, when these boards fail, usually one FET goes short, often the upper FET. So seeing an average of 192V (i.e. Vs) could be fine yet it could be a death sentence for the buffer boards.

The red caps should have approximately the same voltage across them as the output -- they are the energy recovery caps.

Having a scope really spoils you!

[Cooter]

Re: Vizio P50HDM no display or sound

OK, I have a meter and a semi-functional scope, so I can continue testing. I poked around a bit and found some voltages that seem strange, but I don't really know what I'm testing.

When I test between +5VF (on the connector that looks like output from ysus to top y buffer) and the case ground, I get -27.44V. Another point labeled +5V on the lower y buffer gives me a -36.19V. I would think I'd get close to 5V on each of these.

There is a small hole in the ysus board just above where the lower y buffer bolts to it. The hole is labeled "Vsc TP". When I check between there and the case ground, I get about -33.8V, and it continues to drop, such that in the time I'm typing this, it is now -37.8V. Just to the right of it, there is another hole (assuming these are test points) labeled "Vsc TP" also, and I have a fairly steady 75.3V there.

I also tested by placing my positive lead on the GND terminal of the ysus to y buffer board, and the negative lead on one of the board attachment bolts or case ground (same result), and got -41.7V.

Are these negative voltages significant? Have we condemned the ysus or shall I test some more?

[tom66]

Re: Vizio P50HDM no display or sound

The voltages are floating. They are usually relative to Vscw, due to the buffers also floating from ground.

[Cooter]

Re: Vizio P50HDM no display or sound

I think I understand what that means. Do I need to remove the board to test the red caps you mentioned, or should I test something else first?

I can get a pattern on the Vsc TP near the lower buffer board, but I'm not sure what I'm looking for. Do I use the ground on the case, or on the buffer, since the ground is floating too?

Not really sure what to test now.

[tom66]

Re: Vizio P50HDM no display or sound

You can measure the main output relative to ground.
The caps - only one is necessary to check, just measure the voltage across them.

[Cooter]

Re: Vizio P50HDM no display or sound

I have 59.4V across the caps.

Not sure what you mean by "main output".

[MisterD]

Re: Vizio P50HDM no display or sound

I think he is referring to the main output DC Voltages that you are checking on any of the boards by placing your black negative lead of the meter to chassis ground.

[Cooter]

Re: Vizio P50HDM no display or sound

Vs is 192.4V at the power supply, going into ysus, and going into zsus. Va is 59.9V - seems to match the sticker I just found inside...

So it looks like the voltage across the red caps on ysus mostly matches Va - unless it should match Vs...

Any ideas from here?

[tom66]

Re: Vizio P50HDM no display or sound

It would be a coincidence to match Va. Although the Y-sus connects to Va, it only acts to reduce wiring clutter. It passes Va straight to the bottom data distribution boards. It does not use Va itself.

But since you're not getting one extreme it could be OK. I wish I had this chassis here to test because I could verify it. But I try and avoid older LG plasmas because of the IPMs.

[Cooter]

Re: Vizio P50HDM no display or sound

Might be a bit pricey to ship...

I was hoping to replace one or two components on the board, but if it could need an IPM or multiple components, that's probably above my understanding, not to mention soldering skills. Time to get a Y-sus and retest?

[Cooter]

Re: Vizio P50HDM no display or sound

OK guys, I rolled the dice on the Y-sus and had Coppell fix it. That was (99% of) the problem! Picture is great, nice to have it in time for Super Sunday!

So, the other 1% is that a couple times I've seen the picture blank out for perhaps one second, then it comes right back. It's as if someone is changing the channel, but of course the channed doesn't change. My 32" Vizio plasma I was using previously - same HDMI cable, same cable box - didn't ever do this...

Haven't had a chance yet to determine if it is the TV or the input - have only used HDMI 1 input from the cable box at this point. Any suggestions how to troubleshoot this issue?

One other thing, Coppell seems to think that the Z-sus should be replaced at the same time, compares them to sets of tires. Thoughts on the necessity to replace/refurbish the Z-sus at this time?

[tom66]

Re: Vizio P50HDM no display or sound

Z-sus replacement at the same time is unnecessary. Leave it going. If the Z-sus fails, then you need to replace it. A failing Z-sus cannot damage the Y-sus on this set.

The blanking occasionally could be a loose connector, or it could be the ERC IPM having problems on the Y-sus side.

[Cooter]

Re: Vizio P50HDM no display or sound

Follow up a few months later, it made 2 very loud pops, the screen went black, then the picture came back but was very dark. I thought it might be the z sus, so I took the back off and did a quick "sniff test." Good news, my initial diagnosis was correct, bad news, I was back to a 32" TV for a couple weeks and out $100 to Coppell TV Repair for z sus repair. Well, at least it was a learning experience. Thanks, Tom for your help!

[brnrubbr]

Re: Vizio P50HDM no display or sound

FNG here. Same issue. FS3 on Y Sus blown. I replaced the fused and BAM somewhere on the Y Sus went bad. Thankfully I had the back removed from the TV so I can isolate the "BAM".

I think I can safely suspect at least Y Sus is bad. All caps look good and Power Supply checks out. All FETs look good too. I am assuming I will need at least 1 new IC (IC201/IC202)?

I do have the equipment to check anything is you guys have ideas. I also have all the equipment to repair anything. Thoughts? Ideas?

Thanks for any help!!

[brnrubbr]

Re: Vizio P50HDM no display or sound

Yup, IC201 fried. I removed the IC here at work and the thing is smoked. I was able to view under the other ICs and all seems well.

Only issue I will be having is to repair a couple vias (eyelets). Hopefully not too bad of a repair.

New IC will be here middle of next week. Crossing fingers!

[102mm]

Re: Vizio P50HDM no display or sound

I just picked up two of theses models but the components are different in each one. one has 7 bad caps on the power supply. The other has a bad Zsus board as i was told by the previous owner and looks like the pics above.

[b7772er@yahoo.com.sg]

Re: Vizio P50HDM no display or sound

I have a Toshiba 50" Plasma that was flickering for a while and just having a small computer fan providing airflow cleared my flickering problems. two days ago my wife was watching TV and she heard a loud pop, screen went off. I got home and open the back cover to see if there was anything noticeable and all looked good. Turned the TV On, got the status lights but heard three quick snaps on the YSUS board.
The VS - to Ground is shorted
Any suggestions?

[b7772er@yahoo.com.sg]

Re: Vizio P50HDM no display or sound

[QUOTE=b7772er@yahoo.com.sg;754842]I have a Toshiba 50" Plasma that was flickering for a while and just having a small computer fan providing airflow cleared my flickering problems. two days ago my wife was watching TV and she heard a loud pop, screen went off. I got home and open the back cover to see if there was anything noticeable and all looked good. Turned the TV On, got the status lights but heard three quick snaps on the YSUS board.
The VS - to Ground is shorted
Any suggestions?

Model: 50X3
Board: YSUS
Part No: 6870QYC0004C

PSU: APS-219
P/N: 3501Q00200A

Toshiba: 50HP16