Re: Tnpa5081 af 7 blink error trying to repair
Scmitt inverter and Q818 could definitely be a culprit as I found out after numerous failures with the board. From now on, on every board I will replace them, even if, especially Q818 looks innocent in cct. D702 was included in the kit, also read ok, but since it is connected directly to always shorted HA inverter, would be safe to replace it too
But, man, I'm still on cloud nine after fixing the board yesterday...
bregva
Member
Last Activity: 11-04-2019, 03:11 PM
Joined: 05-09-2013
Location: Los Angeles, CA
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Re: Panasonic sc tnpa5081 rebuild
I use Ebay, it's easier to control shipments and communicate with sellers
I just got 3 or 4 from UTSOURCE, other parts in the order were fine, so I figured why to bother. But here is a pic of 2 transistors side by side, so you can see the difference...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
No, I did not take pics, bummer!
Some of TO220 components looked aftermarket with thin pins, I was even afraid to brake them while bending for install, I just don't remember which ones. Q661 was substituted by RJP63F4A FYI
So in case I'm short on DG402, which currently I am, is it OK to sub them with DG502's?
I would recommend sourcing parts individually, I usually get small components like HA inverter, 3Y marked transistors or micro SMD diodes directly from Panasonic, they are inexpencive and OEM quality. As for TO220 I source...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
Success!!!!
TV fired up fine, I was on cloud nine, customer had to pull me down
But before I delivered it, I decided to check one more time and here they were, I missed pair of 30f125's, sure enough they were not included in the kit.
So, I'm thinking what was the reason I had no success on previous repairs on these sustains? Was it Q818, was it opto coupler, IC771 or was it D702? I have not replaced them before. Q818 out of cct measured strange, reading was kind of running up to .550, not instantaneous like on the new...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
It's been a while since I worked on these boards. My customer bought repair kit from Shopjimmy for his TCP50G25 and now I'm installing it for him. Board version is AF. Here is list of parts in this kit:
Q660
Q661
IC501, 521
IC771
D451
D702
D482
Q701
Q421,422
R402,403,421,422
D641,642
Q452
Q402,403
PC461
And last but not least Q818, and I have question about this transistor
As you can see in pics, original one is smaller and marked KN,...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
Can you give me reading on D790 from your working board?
In diode measuring mode...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
"Do you connect 4 screws for HV on the buffers while main connectors are disconnected?
I did not, buffers were totally disconnected"
That was really stupid question, I just checked troubleshooting guide and yes they should be disconnected. However I don't see any reasons why flat cable between buffers has to be disconnected also, they are not getting any power anyway!
Will have to check for shorts in 15v and Vda lines, Vs is good, checked alreadyLeave a comment:
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Re: Panasonic sc tnpa5081 rebuild
Have I missed some action since I was here last time? That's for shure!
Today I got some parts I was waiting for, but not all, still waiting for extra 30F125's and RJP63F3A's
I started with rebuilding AL board I borrowed parts from. Put back 2 DG502LW, 2 DG402RP and RJP63F3A. Nothing else was taken from this board and it was supposed to be working.
Plugged it with buffers disconnected and SC50 shorted
Got VS 203V for a few moments and then SOS 6.
It did make loud "trrrrr"...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
Thanks, I'll check that tomorrow
Here are results of today's testing
First of all there are no resistors in location R552 on all boards I have
I wanted to show picture, but can't figure out how to attach it to the text
R521, 522 checked 100ohm on all
R707 3.9K are good on all
IC691 compared well to good board on all
R680 measured 4.7k on all
I can't find opto PC561, can you help?
I found interesting measurements on D790. In diode...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
OK, finally was able to get to this project again
I'll try to answer your questions
Yes, I decided to fix the board versus buying replacement after finding this forum, and don't regret doing it even though replacement parts will eventually cost me almost same after all, but that itch was hard to resist, what can be better than learning something in the field you work and you love what you do
Anyway, I have already 4 SC boards in my posession since I started
1 AF version from the TV (not working, project)...Leave a comment:
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Re: Panasonic sc tnpa5081 rebuild
Hi everyone, I'm new here on the forum
I'm trying to repair the SC board, replaced all shorted components, but Q661 failed again on power up. I'm having hard time finding that C741 you mentioned, can you pin point it for me? It is on SC board right? I powered the set with buffers connected, but buffer boards seem fine, there are no shorts on them. Another thing, I did not change IC 501 as it seemed OK. I just changed another M81737fp as it had short between pins 7 and 8. Other than that I would not know how to determine if...Leave a comment:
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