panasonic 47x54 problems


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panasonic 47x54 problems

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capted
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Jan 17, 2008, 10:40 PM

Post #1 of 7 (1712 views)
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panasonic 47x54 problems	Can't Post

Just found this forum and looks great. I figured I'd ask around in this forum to see if anybody has any ideas!!
My panny pt-47x54j has what looked like a convergence problem. So I changed the stk 394-210 chips and checked the resistors. Still no go. The screen looks like it has a pincushion problem(pulled inwards on all 4 sides of the picture. The colors are not converged together. I did notice there is a ds-board that also controls convergence(all surface mount chips). The service manual states just to replace it(not repairable). But I also noticed the audio went out at the same time the screen went funky..
So I took the chassis out and set it up on my bench. I checked all the main voltage check points showed in the service manual. All O.K. but the 18v line is 22v. After looking at the schematic to see what was common for the convergence and the audio it seems to be the 5 volt power circuit. It feeds the convergence eeprom and the audio amp. But it has 5 volts??? Now I'm lost. My next step will be to check all the powers to each chip.. I did order the ds convergence board because it also feeds off the 5 volt line. There is no checks for this board so I'm thinking somehow it maybe causing a problem on the 5 volt line.
Any of you pros have any ideas or have seen anything like this????? I am very comfortable with electronics so I'm up for any ideas. Thanks,ed

mikemaiertv
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Jan 17, 2008, 11:18 PM

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Re: [capted] panasonic 47x54 problems [In reply to]	Can't Post

Basicaly if the set does not have the five volt line it will not turn on, Better check the supply voltages for the convergance Ic's them selfs, if they shorted it may have taken a 5 amp pico fuse somewhere on the 28 volt line
Mike Owens Owner Competition TV Spokane WA.

techchris
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Jan 17, 2008, 11:22 PM

Post #3 of 7 (1706 views)
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Re: [capted] panasonic 47x54 problems [In reply to]	Can't Post

could be anything from a corrupted eeprom to a power supply fault.take the STK's out and see if the sound comes on. if not the convergence is probably ok. if it does something is still wrong in the convergence area causing the micro to mute the sound

capted
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Jan 18, 2008, 12:18 AM

Post #4 of 7 (1702 views)
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Re: [techchris] panasonic 47x54 problems [In reply to]	Can't Post

Thanks you for the response. I will check the 28v line. I will check the convergence power also. Good to know that if the 5volt line is out the set will not power up. I do see a mute line going to the convergence area also and it goes back to the audio section. That add on pc board is also a convergence section so I am thinking it could cause a problem also. I will keep checking!!! If I take the stk's out will it cause any harm to the other components??? Thanks again,ed

mikemaiertv
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Jan 18, 2008, 6:39 PM

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Re: [capted] panasonic 47x54 problems [In reply to]	Can't Post

Before you get totaly sidways gutting the e-prom and ripping the audio apart, Test the power for the convergance Ic's pin 8 should be -20 and pin 10 +20 if thats gone simply follow it back to the power supply and see where it dies
Mike Owens Owner Competition TV Spokane WA.

capted
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Jan 18, 2008, 8:02 PM

Post #6 of 7 (1686 views)
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Re: [mikemaiertv] panasonic 47x54 problems [In reply to]	Can't Post

I started checking the powers at each chip So far all is good!!! I checked the stk powers and they are all good.. This is why I'm losing my mind!!! I did not get them all done yet though. Hopefully I will find that (I can't believe I missed that!!!)one. As far as an eeprom goes, it seems to store the info and any changes I make with no problems. The convergence lines do move when I adjust them also, just not far enough. Not a setting or service menu problem for sure. The only piece of the puzzle is this other add-on convergence board. There are a bunch of big chips on it. No info on this board except to just replace it if it is bad(DUH!!). I am wondering if this board controls the auto convergence on the set??
It's bugging me that so far every power test is good and there are no physically bad components. This set is only 3 years old. My mitsu is 6years old and only had to resolder the stk's...(oops, maybe I shouldn't push my luck)...
Again thank you for your help. I really appreciate it. Any other ideas??? I will check ALL of the chips powers and power supplies just to be sure. There must be something in common with the convergence and audio.. And the schematics I have are missing one page of the d-board. Guess which one---the one with the second convergence amp.. Go figure. Just using a scematic from a bigger model 53x54 for the missing page.. I hope it is correct.

capted
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Apr 30, 2008, 3:48 PM

Post #7 of 7 (1571 views)
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Re: [capted] panasonic 47x54 problems [In reply to]	Can't Post

Started working on this t.v. again... Does anybody know where the pincushion circuit is? I have the boards out and I'm checking all the components but this is making me cross-eyed!!! Just seems to be a pincushion type problem and not a convergence one...

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