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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Tue May 04, 2010 6:25 pm Post subject: Craigslist fixer-upper plasma: Ideas? |
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There's a guy on CL selling an older plasma. It's only 852x480, but I don't particularly care since I only watch NTSC upstairs anyway; the previous EDTV plasma I had made NTSC look great.
It's a Vizio P46 - we're not talking Pioneer Kuro here, but since my Tosh RPTV died I'm suffering with a 32" LCD which won't even expand 16:9 letterboxed content, so half the stuff on TV is 16:9 in a three-inch black frame in a 32" LCD. 
Here's what he says:
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(in the ad)
Images ghost / distort on the screen. Running it with the Y-Sus disconnected gets a clear but dark picture.
(and via email)
There was a broken / burnt connection on the main power supply that
went to the y-sus. That connection was repaired. I was able to adjust the
voltages to where they had to be after that was repaired. There is a tech
training manual on the web for the P46, you can DL for free. From what that
is telling me the problem is within the y-sus now.
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Any ideas? He wants 60 bucks for the thing, but I don't want to blow a chunk of change and the (long) drive to get it if it's gonna be a lost cause or dozens of hours of troubleshooting.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed May 05, 2010 12:09 am Post subject: |
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Geez, I've been waiting for Curt to respond to this one, lol. I'm curious to his reply.
How about a complete model number while we wait. There are so many variations to these that an exact model is really required to give any suggestions.
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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Wed May 05, 2010 1:34 am Post subject: |
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Bad chip on the Ysus board most likely. Very common. Removing the bad chip is a royal bitch, you need patience. I've been buying plasmas here not working for $100, and have about a 50% success rate of repair. I either buy boards on eBay for $30-100 used, or am now buying the chips at $30-35 and putting them in myself. It's a learning curve, but this seller did most of it for you.
Also, it COULD have a bad Zsus. Mac, correct me if I'm wrong, but the Zsus controls brightness, not the Ysus..
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Wed May 05, 2010 5:56 pm Post subject: |
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| Curt Palme wrote: | Bad chip on the Ysus board most likely. Very common. Removing the bad chip is a royal bitch, you need patience. I've been buying plasmas here not working for $100, and have about a 50% success rate of repair. I either buy boards on eBay for $30-100 used, or am now buying the chips at $30-35 and putting them in myself. It's a learning curve, but this seller did most of it for you.
Also, it COULD have a bad Zsus. Mac, correct me if I'm wrong, but the Zsus controls brightness, not the Ysus.. |
On the newer design plasmas this would be mostly correct. How ever on the earlier designs it does not apply. For 1, the earlier design did not use IPM's, they used discrete semis. Next they didn't have a Z-sus but rather an X-sus and a Y-sus but the X did not function like the Z and as such the Y did not function like the newer design Y.
The Y in this design did affect brightness.
What bothers me about this one Peri is the guy was already hunting around trying to fix it and was unsuccessful. He was also messing with a bunch of voltage adjustments.
Now the fact that the image problem seems to go away when the Y is disconnect and the picture is dim has no relevance to the problem, meaning it doesn''t mean the problem is in the Y. It could be just the fact that the image has no brightness and is unable to produce enough light to show the image problem.
Of course that also doesn't mean the problem is definitely not the Y. Or it could be he just doesn't have the voltages just right. Plasma voltage adjustments are very sensitive and critical.
Even the manufacturer states that when you have image problems, "change this board, if that doesnt cure it then change this board, and if that doesn't cure it then change this board".
Even they just recommend board changes and dont have definite troubleshooting procedures.
Add to this, what if the boards for this older one are unavailable either new or used. Maybe this is why he gave up. He couldn't find boards for it.
Basically I waited for Curt to reply figuring he would say something like, repairing these flat panels are like shooting in the dark. If someone finds a fix for a common problem then you may have some luck. If not then you are just changing boards until the problem goes away and if it doesn't go away then you have a bad panel, which is unrepairable.
AREN'T THESE NEW TV'S JUST WONDERFUL....................
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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Wed May 05, 2010 8:08 pm Post subject: |
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Yep... OK, so, sounds like this is a no-go unless it's a freebie then. Too much risk of another paperweight. Thanks!
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