Panasonic sc tnpa5081 rebuild

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Also, I'm getting a ~65 ohm reading on collector to emitter on Q702. I will check my buffer boards when I get home.

That's bad, in cct mine rises until it gets to 2.7k ohms. I would remove from cct and confirm and also re measure the pads on the board minus q702. Shorted Q702 is expected.

This photo is playing up in the earlier post.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Hey guys, slight thread bump... this is the best source of info for this board that I was able to find. My TC-P54G25 just bit the dust, pretty much 3 years on the nose from when I bought it! Got the 10 blink code, so I disconnected the ribbon & power to the SC board and it went to 6. My first question is, is the damage usually isolated to the SC board or do the SD & SU boards get fried too? Thanks to this thread I was able to find some components that were bad. I'm an amateur when it comes to troubleshooting, I work with electronics as my job but we're far more into the replacement industry if you know what I mean. So far here is my list of dead components (checked when removed from circuit):

D482
Q452
Q401
Q402
Q403
Q421
Q422
Q423
Q660
Q661
R452
R551

Is it assumed the FET drivers always go on these(IC501, IC521)? Also, what's the best way to check those double transistors? (Q551, Q521, Q501, Q531) I don't have the board in front of me right now but no pins were shorted except where the bases connect obviously. One other thing I found was a 13 ohm reading across the 5V reg. from common to output (IC771). I took it out of circuit and the resistance is still there. The reg. itself is showing about 5.6k now if I remember correct.

(Q551, Q521, Q501, Q531)CPH5524PNP / NPN Epitaxial Planar Silicon Transistors -High-Current
These are not easy to find either, Mouser shows nil until mid November, Digikey min order qty3000!
I purchased a very cheap SS board to salvage these from, also produces some other handy bits.
I think it was only my last cooked board that needed these, you may since R452,D482, Q452 are in the bad list

Q551 in cct.

3-5 0.7 ohms
3-4 3.5meg
4-5 3.5meg
1-2 jumps around > 150k
1-5 3.6meg
1-4 47k
2-3 3.5meg
2-4 similar as 1-2 >150k goes over 200k and slows.

This is what I've had to replace in that area, but not all boards mainly the last one after too many failed powerups. generally just the FET driver

D16451 B0ECKP000055 DIODE 1 ROHM , RF101L4S 400V 1A SHORT
D16482 B0FACP000003 DIODE 1 RFN25TM4SWSHORT
Q16452 B1JAEP000012 TRANSISTOR 1 GT45G128SHORT
IC16521 C0ZBZ0001708 IC 1 M81737FP
Q16521 B1HFPFA00001 TRANSISTOR 1 CPH5524-TL-E
Q16551 B1HFPFA00001 TRANSISTOR 1 CPH5524-TL-E
R16452 D0GF5R6JA047 M 5.6 OHM,J, 1/3W
R16521 ERJ6GEYJ101V M 100 OHM,J,1/8W 1
R16522 ERJ6GEYJ101V M 100 OHM,J,1/8W 1
R16551 D0GD100JA059 M 10 OHM,J,1/4W 1

[tom66]

Re: Panasonic sc tnpa5081 rebuild

If you can get the datasheet for those devices acceptable subs can probably be found.

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

Q702 now removed, definitely bad... I am now seeing the 2.7k across the pads. Big 7805 checks out ok. I'm getting a lot of 47k to 52k readings across various pins of Q551. The surrounding R521 & R522 are right on the dot 100 ohms, D451 survived reading a good .488V drop. I'll post more findings later!

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

I've misplaced my fine probes ,hard to get on it, you'll have to be more specific with Q551. I guess Q452 D482 are definitely shorted?

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

Yes those two are shorted. Here's my Q551 readings:
1-2: 100k
1-3: 54k
1-4: 52.5k
2-3: 47.3k
2-4: 46.8k
3-4: 543ohms <--interesting.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Yes those two are shorted. Here's my Q551 readings:
1-2: 100k
1-3: 54k
1-4: 52.5k
2-3: 47.3k
2-4: 46.8k
3-4: 543ohms <--interesting.

This is definitely not good, 1-5 & 2-3 should be in Mohms. I put an old diagram I've posted before. The figures are ballpark but around the 2.9-3.5meg.

I was afraid these may be dead.(just realised R551 10ohm is listed, so yeah fried I say)

What's happening with the others, primarily Q501?

have you developed a strategy on how you're going to obtain these parts?

I've placed red dots on the items you've reported bad. Q660 is bugging me, it's shorted too is it?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

I meant Q521?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

looking at the cct a bit more and what's fried, replace IC521

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

Q660 has indeed seen better days. Here's the readings from Q521:

1-2: 2.66k (charges up)
1-3: 2.86k (charges up)
1-4: 49k
2-3: 277ohms
2-4: 47k
3-4: 53k

Haven't checked online for parts yet, if I have to wait for Nov for the dual transistors that's fine. Also, the smaller 5V reg (IC771) is showing 5.6k across Vout & gnd when removed from circuit... I'm guessing that's shot?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

IC771, what's Vin - gnd? The same?

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

I do have a suggestion for you if you're into recycling parts if you're interested.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Q660 has indeed seen better days. Here's the readings from Q521:

1-2: 2.66k (charges up)
1-3: 2.86k (charges up)
1-4: 49k
2-3: 277ohms
2-4: 47k
3-4: 53k

Haven't checked online for parts yet, if I have to wait for Nov for the dual transistors that's fine. Also, the smaller 5V reg (IC771) is showing 5.6k across Vout & gnd when removed from circuit... I'm guessing that's shot?

1-2: same as P15V in if you look at the schematic,reverse the probes and you'll see the 1.5k you reported
1-3: 2.86k (charges up)
1-4: 49k
2-3: 277ohms
2-4: 47k
3-4: 53k

That one's stuffed too, basically 1-5 , 3meg, 2-3 2.9meg

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

I do have a suggestion for you if you're into recycling parts if you're interested.

I'm open to any ideas.

Vin to gnd is about 28meg.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

I'm open to any ideas.

Vin to gnd is about 28meg.

? 28meg

On brand new STM 78L05 I have 4.2k Vout-gnd, 8.8Meg on Vin one polarity, 3meg the other. If you get that high a resistance I'd think it's no good, safer to just replace it if in doubt.

There's a 60" SS board in kentucky $10 USD free std delivery, that will yield

1 FET driver
5 npn/pnp (5pin)
gate resistors
A Fast recovery diode for D482, small switching diode for inverter cct if needed.

The FET driver alone is $4 from china from memory.

So none of the 30F125 IGBTs are gone on this?

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

Ok I'll check out the SS board thanks for the heads up. I have 78L05 SMDs at work come to think of it. Q622 & Q621 seem to be ok, the only lower resistance I see is 47k across emitter to insulated gate, which looks like it should read be with R763 being there.

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

Well Q551 is toast, seeing 500 ohms across pin 4 to 5 emitter junction when out of circuit. Pulled Q521 actually seems ok out of circuit, the 2 to 3 pads are still seeing 277ohms...

[Stryff]

Re: Panasonic sc tnpa5081 rebuild

Ah I see where the resistance is coming from, I should've checked the schematic first. The FET driver IC521 has that resistance when I removed it from circuit.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Ah I see where the resistance is coming from, I should've checked the schematic first. The FET driver IC521 has that resistance when I removed it from circuit.

http://www.ebay.com.au/itm/PANASONIC...item485b769fc7

There's a few cheapies, I was between a rock and a hard place for those sanyo transistors so this option was actually the easiest and cheapest but if you did need some 30F125 there's some of them on there and also the tiny C541 buffer ic which also i needed and impossible to get .

AT least you could order from sears if you really had to for OEM but can be expensive.

Good, just definitely justifies replacing the FET driver.

[tw2005]

Re: Panasonic sc tnpa5081 rebuild

Well Q551 is toast, seeing 500 ohms across pin 4 to 5 emitter junction when out of circuit. Pulled Q521 actually seems ok out of circuit, the 2 to 3 pads are still seeing 277ohms...

I still don't like Q521, if that was correct I'd be seeing that in cct , not worth it. Compare the same to one of the others.