Panasonic TC-P58VT25 10 blink

[Alastair E]

Re: Panasonic TC-P58VT25 10 blink

Without the IC771 in, between tab and left-pad, you'll get around resistance climbing to around 1Meg on a 5081 board when there's nothing shorted/leaky/buggered in the inverter stage and transoptor...

the 5.6K With the reg fitted--is the pot divider network Inside the reg-chip and varies between different makes--5.6K is with a good original, but I used a different make reg, this reading was around 3K as I recall, which caused me some time potching round....

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Without the IC771 in, between tab and left-pad, you'll get around resistance climbing to around 1Meg on a 5081 board when there's nothing shorted/leaky/buggered in the inverter stage and transoptor...

the 5.6K With the reg fitted--is the pot divider network Inside the reg-chip and varies between different makes--5.6K is with a good original, but I used a different make reg, this reading was around 3K as I recall, which caused me some time potching round....

With IC 771 in I had pretty close to that reading. After the meltdown, I checked it and it was 55 ohms.

I then removed 771 and checked the pads and still had the 55 ohms. I am fortunate to have another TNPA5175 board that I can compare.

So far the PC4856 shows different readings and Q702 reads about 55 ohms on all leads. I will continue tomorrow and remove Q702 and see if IC771 straightens out.

I work in the garage and my computer was in the house. So I moved the computer to my work bench and I can zoom in on the schematic and ck each part

Pretty ingenious don't you think!!!!

[tw2005]

Re: Panasonic TC-P58VT25 10 blink

Yeah except i thought of it first. I have a laptop on my bench too and i expect most of us do ��

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

I know it wasn't genius at all, kinda stupid for not doing it 5 years ago. Imagine the huge waste of time looking at the schematic, writing done items to check, and the going out to the garage.

No wonder I am always tired

I don't own a lap top so it was moving a desktop out to the garage.

.

[tw2005]

Re: Panasonic TC-P58VT25 10 blink

I know it wasn't genius at all, kinda stupid for not doing it 5 years ago. Imagine the huge waste of time looking at the schematic, writing done items to check, and the going out to the garage.

No wonder I am always tired

I don't own a lap top so it was moving a desktop out to the garage.

.

yeah, whatever works. I had to lend mine to my daughter. went into the work area and constantly looking for it so I could use the diagrams. what a PIA it is without it.

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Ok, so now that I am organized, just had a few questions. I have the spare board which I already borrowed a diode and resistor from.

UTSOURCE looks like they have a lot of items on the 5081 rebuild, but I was thinking of just borrowing parts from my spare.

Some of the small stuff I know just sticks to your iron, but is there any chance
of ruining the small parts on removal?

The only other concern is twice as many parts to remove and reinstall.

Anybody have any advice on this. Thanks

[tw2005]

Re: Panasonic TC-P58VT25 10 blink

If it was the larger parts maybe but giveñ what these are worth why would you risk damaging it. Sell it or compare the 2 and see how hard it is to convert to the other version. Is it not easy and cheap enough to get these local?

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Thats what I kinda thought. I dont have a local parts place, at least one thats reasonable.

I started checking everything and so far have the Q701 and Q702 shorted. the real problem is I have a short on the pads of IC771. its the left pad to center is shorted.

I have removed all the shorted parts hoping the short on the pads of 771 would go away, but still present. I also removed some items related to that circuit and no go.

I have been using the other board for comparisons.

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

If it was the larger parts maybe but giveñ what these are worth why would you risk damaging it. Sell it or compare the 2 and see how hard it is to convert to the other version. Is it not easy and cheap enough to get these local?

Sorry, didn't answer all your suggestions. I am not sure what the difference is in the boards. They are identical as far as the large heat sink components.

I guess I can lay them side by side and look thru my magnifier to see if I can see any differences.

You are right, that would be the ideal solution. Thanks

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

I guess its a whole lot easier to compare schematics. I already see some changes on page 4 of the schematic for the SC board by the SU connector. Looks like some caps are added.

I will look closer tonight at the schematics to see if there are any more changes.

[Alastair E]

Re: Panasonic TC-P58VT25 10 blink

Short on the Transoptor...?
--Thats basically the only thing left on that 5V rail after Q701, Q702 D701 and IC773 been pulled....

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Thanks for reply. If you are talking about PC16461, I pulled that also. It wasn't shorted, but had real bad readings compared to my known good board.

I ran out of things to check or maybe I just got tired. I will check some more tonight. Thanks

[tw2005]

Re: Panasonic TC-P58VT25 10 blink

somethings's not right. 99% of the time it's ic773 shorted, Q701,702Q818 i would replace regardless.

PC461 can cop it , I've only had 2 boards needing one of those, a 5066 SN and a 5081.

maybe check there is not a solder dag left behind

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

I felt it was a little strange too. I have ic773,q701,q702,d701 pc461 , ic771 all removed. I didn't remove q818 but it wasn't shorted.

I will spend some more time looking, maybe there is a solder bridge somewhere
but I already looked once for that. May be it was just late.

I will quit bugging you guys on the forum until i figure this out. i have learned a lot about this board on this go around so---THANKS

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Just an update, I found the short after spending a ton of time. It was actually c708 was shorted which is off IC773 vcc to ground.

As soon as I removed it the short went away. I compared to the other board and the resistance across c708 was 6.3k ohms.

now the problem is to find. the other problem is the schematic shows .1uf 50 volts, but the parts list shows .1pf 50 volts.

What would be the best to use if not sure? I thought the .1uf but not sure.

hard to believe I went from a 10 blink code to a 6 blink code and the back to the 10 blink. I sure hope I get it this time around.

Her is my parts list:
Q701
Q702
IC771
IC724
IC773
IC501
D702
PC461
D451
D402-403
DG402
DG502
C708


I am placing my order thru UTSOURCE so it will be awhile till get it all back together. Thanks

[Alastair E]

Re: Panasonic TC-P58VT25 10 blink

0.1uF decoupling-cap.

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Thanks, appreciate that. Just have to find it now.

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Next question I have has to do with the D16451 and D16652. Both are identical in the the part numbers and the schematic.

Originally my D16652 was shorted and it was included in the kit I got. The original marking on the 451, 652 look like 8308.

The replacement marking is 6651. Anybody know if it will work. I know tw2005 had a replacement of RF101L4S.

I had a few spares of the 6651 but of course not sure if the kit had wrong part or they are interchangeable. Thanks for any help.

[tw2005]

Re: Panasonic TC-P58VT25 10 blink

Tough question but if it looks similar you will have to try and find a rohm diode datasheet with marking 66

[gdawg]

Re: Panasonic TC-P58VT25 10 blink

Tough question but if it looks similar you will have to try and find a rohm diode datasheet with marking 66

I think I will just order the ones you show as a replacement-RF101L4S. They are cheap enough but just thought I would use what I had.

I was trying to find data sheets on either one and I must not be using the right key words to find either of them, Thanks.