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Having shutting off problem, along with blue convergence issues!

I am a Major Appliance Servicer for 29 years, but TV's are not my forte, although I feel very qualified to make a repair. I will try to explain the problem as best I can.
I have a Panasonic 2000 model PT-51HX40B that has a shutting off problem, along with blue convergence issues. The set shuts itself off, and directly seemed to be related to the volume level. If the volume was turned up to maybe create a little more bass reverb (level15) the set would shut off after a few minutes. I removed the back and cleaned the dust off of all of the circuit boards, cleaned mirror, lenses and inside screen, and checked connections. I didn't really find any bad connections, and I turned on the set and watched and listened to what was happening. When the volume is turned up, on what I would call the power supply board, there was what sounded like a relay that would click in and out irradically. This would not alter the picture, but eventually the relay would click about 20 times, then the set would go black. It sounded as though it was still powered up, but I would here the sound of things cooling down. I noticed a heat discoloration on a circuit board (TNPA1412) around what looks to be a diode (has an S,G,and D on the board where the three terminals of the part are soldered). I found that if I put a pressure on the circuit board, pushing it towards the front of the set, that this seemed to cause a resetting of something on the power supply board, and I could then turn the machine back on with the remote. I removed the TNPA1412 board and inspected it, finding nothing obvious, reinstalled it and it continued to act the same way. I eventually cable tied the upper corner of that board to some metal framework in front of the board, causing a slight pull on the board, and tried it out. The set hasn't shut off by itself since (4 days), and I have cranked the volume quite loud. I know it sounds like a connection issue, and my cable tie isn't a permanent fix, but if it is working is there anything that should be done?
I also seem to have a problem with the blue convergence. If I center the blue convergence in the center of the screen, the extreme right side 4 inches has a tendency to have a blue shadow to the left of any vertical black object, and the extreme left side 4 inches of the screen has the blue shadow on the right side of the vertical black objects. I have to find a happy medium and live with it for now. I also have blue shadowing horizontal objects on the very extreme top and bottom. Any ideas?
The picture is plenty viewable, but my eyes keep catching the glimpses of blue on the ouside edges. If there is a fix that isn't too costly, or any help ideas out there, I would very much appreciate any information on this subject.

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  • 4 more comments 
  • whisky7 Feb 06, 2008

    Thanks Terryfic

    Any idea where I can find a service manual or parts breakdown for this model? I am curious to know if you have any idea as to what the cost of these parts are, as I presently have the set for sale, and would like to know what to tell the buyer, If it doesn't sell, then I will repair it for myself. I see a lot of people asking for a service manual for this model with little success.

    I would also like to know what the TNPA1412 board is and does? The part I was explaining in my last post that I said looked like a diode, I meant to say a triac. I'm curious as to if the poor solder joint could be causing any of the blue convergence issues?

    Thanks again for any help that you have and can give me!

  • whisky7 Feb 07, 2008

    Thanks Terryfic for the extra information.

    I also wanted to add that after adjusting the blue convergence, the next day it seems I have to let the set warm up and readjust as it seems something is constantly changing.

    The TNPA1412 is the part number on the board that contains the triac with the heat discolored area, and is also the board the I presently have cable tied in place with the bad solder joint.

    I don't have a service manual, schematic, or even a parts breakdown for this unit to identify the names of the boards. Without having either of these, it is very hard for me to service this tv correctly, as I don't know where to look for the blue convergence board, large heat sinks, b+ resistors, ect.

    Sorry to sound so inept, as I'm really not, it would just help a great deal to get a hold of a schematic diagram or anything that would help me identify what I am looking at.

  • whisky7 Feb 07, 2008

    Ok Terryfic,

    Here's what I have found. I've located the 2 large heatsinks on the main board, and they are indeed the STK392-110's. The resistors next to these 2 heatsinks look fine with no signs of heat or burning. I also see the numbering on the board under these heatsinks stating IC7001 and IC7002. Are these the convergence IC's that you speak of, and are they mounted underneath the heatsinks? Everything here looks normal.

    I talked with my Brother, who owned the TV before I got it. He stated that immediately after the delivery of the new TV to his home that he had the same problem with the blue convergence. He had a serviceman come out with a book about 6 inches thick, and the serviceman proceeded to make an adjustment through some service menu (special channel) that adjusted the screen geometry. This corrected the issue, and the set worked fine for some time. That was until he had a power outage, which seemed to put the TV back to its' original setting, and back came the blue shadowing on the edges. He learned to live with it, due to the fact of having no warranty left. Do you have any idea what service code or adjustment procedure can be used to accomplish a screen geometry adjustment, as it may be worth a try before replacing components? Question I have is can you adjust screen geometry for one particular color, or is adjusting for a correct blue going to throw off the reds?

    I know I am asking a lot of questions, but I really hate the thought of having to replace components on the boards if it is not needed, I am not to proud to admit when a repair is beyond my expertise, and am willing to get help if needed. Let me know if you can help me out, and thanks again for all the help that you have given so far!

  • whisky7 Feb 08, 2008

    Thanks for the link Terryfic!

    I entered the service mode just to see if the code works on my model, and it did. I made no changes, nor did I enter any menus, just used the power button on the remote to toggle through the menu choices. There appears to be six menus, then it returned to the original red CHKOFC09 48404840. After seeing that I was going to need more information before tackling any adjustment, I wanted to get out of the service mode. The problem is that I dont seem to be able to get out. I tried volume up on the set and nothing, also tried setting sleep timer back to 0, and setting tv mode back to "tv", still keep getting this CHK line on top of screen. I turned of the tv via the sets power button, and turned it back on, now the CHK line still appears on top of screen but now reads CHKOFC09 00000000.

    I'm not sure what will happen if I just wait for the 30 minute sleep timer to expire, whether it will kick out of service mode or what. If you can tell me how to get it out of service mode I would greatly appreciate it. Thanks

  • whisky7 Feb 08, 2008

    Just wanted to let oyu know that I did a little more research and found that by holding the power and action button on the tv for 5 seconds, that it did a "soft reset", tv restarted showing everything ok on the self test. Funny thing is that it may just be me, but the picture seems to look a lot better.

    I will hold off on doing anything to this set until I decide whether I am going to keep it or sell it.

    Thanks for all the help Terryfic!!

  • Anonymous Jul 14, 2008

    I also have a 10 year old Panasonic TV that shuts itself off especially after turning it on the first thing in the morning. In 2 or 3 minutes, it comes back on, I have tried unplugging it overnight, changing the batteries in the remote and actually have taken the remote out of the room to see if that had any effect. It does not happen every day, only occasionally.




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1) Definitely a bad solder connection..I use a magnifier...

2) Blue convergence IC bad....change both for reliability
Located on large heatsinks on main PCB.......
Check B+ resistors for over-heating...............................T.

Posted on Feb 06, 2008

  • 3 more comments 
  • Vista Electronics Feb 07, 2008

    Blue Convergence issue seperate,unrelated to bad connect

    in power triac circuit.....................T.

    TNPA1412 = ??

  • Vista Electronics Feb 07, 2008

    Practice visual acuity technique ! Your biggest asset is looking

    the situation over....identify the largest heatsinks,look at the

    part number on them....STK392-110 (verify) replace BOTH...

    LOOK at resistors next to IC's ....if burnt = replace...

    Solder the over-heated area + check any electrolytic caps

    in the area that ran hot.....use ESR meter if you have one

    or touch top of cap to see if it is warm........

  • Vista Electronics Feb 07, 2008

    TNPA1412 = PTS rebuild only.....75.00...

    TNPA1798 = PTS rebuild only.....180.00....J - Deflection

    On J PCB are the convergence IC's....IC7001 & IC7002

    STK392-110 sub (upgrade) to STK394-160E.......................... use Hitachi part # CZ 01341...................................T.

  • Vista Electronics Feb 08, 2008

    Please review this post ( PT47WX49E similar to your set )


    Note: DO NOT USE generic IC's !


  • Vista Electronics Feb 08, 2008

    Exit service mode = change channel off 124, then power off,

    then power on. ........................................Terry.



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