tc-p50S2 10 blink SC troubleshooting

[carpetweb]

Re: tc-p50S2 10 blink SC troubleshooting

I had an sc board blow on my tcp50g25 13 months ago and replaced it with a new board...now 13 months later it blew again....I'm thinking its not worth the headache to find another board and repair it again. Will NEVER EVER buy panasonic again.

[allenrw]

Re: tc-p50S2 10 blink SC troubleshooting

Here is the latest update, I started pricing parts and because they came from different sources including used Panasonic boards the price rose quite quickly and there was no certainty that I had found all the bad components.

I sat back and watched Ebay.
Don't you know it a week ago someone posted a SC, SU, SD board set as a new pull for $117 US delivered.

It works fine so far but I think there may be a clue as to why these boards go bad, some of the heat sinks get a bit warm so I am considering a couple of low noise fans mounted externally.

Thanks for the help TW2005, you made this a lot easier but it was still very time consuming, a great learning process.

My advice for a repair like this is to take the time to check the TV carefully at the component level looking for shorted components and missing voltages to determine which boards are bad (the blink codes were a bit misleading), then if it is a couple bad components that can be had for reasonable money fix it up, but if it turns out that there are many components then it is probably better to get a warranted used board.

The trick here I think is to take the time to verify that you find all the problems so you don't end up buying parts or boards and then have to buy more boards or damage your new boards because you missed something.
Once I discovered that there was a short in the SC board I disconnected it and checked the voltages on the P and A boards pretty carefully especially those related to the SC board.
It has been an adventure!

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

Yes


None of them are shorted, but not really a guarantee they are good.



I am assuming you are talking in respect to the circuit ground. If so
the yes I did. The resistance measured up into the kilo-ohms, on both
the 5 and 15 volt lines.

k ohms sounds like it could be ok, fet drivers usually go open on the output and or short or low ohms on the Vcc which i believe is the 15V in from the few I've played with but not your model

[glen65]

Re: tc-p50S2 10 blink SC troubleshooting

Ok, well hope it works out. By all i assume all the SMD stuff as well,

Yes

the voltage regulators and possibly failed inverter ICs,

None of them are shorted, but not really a guarantee they are good.

did you measure the resistance for the P5V and P15V lines in.

I am assuming you are talking in respect to the circuit ground. If so
the yes I did. The resistance measured up into the kilo-ohms, on both
the 5 and 15 volt lines.

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

Ok, well hope it works out. By all i assume all the SMD stuff as well, the voltage regulators and possibly failed inverter ICs, did you measure the resistance for the P5V and P15V lines in.

[glen65]

Re: tc-p50S2 10 blink SC troubleshooting

UTSOURCE ,would have them and possibly Ebay.

DG502LW should sub ok for the 2PG011, AFAIK that one superceeded it.

RJP6065, i suspect RJP63F3 would do there

At a couple of bucks each from UT, I'd take a chance but I do not recommend purely replacing the IGBTs that are shorted and expecting it to then work.

odds are they will simply blow again.

I wouldn't either,
That's why I checked all other components such as transistors, diodes resistors, ect.
Also checked the FET output pins of the M81707FP ICs for shorts. The SD and SU boards
can be had pretty cheap, and might change them for good measure.

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

UTSOURCE ,would have them and possibly Ebay.

DG502LW should sub ok for the 2PG011, AFAIK that one superceeded it.

RJP6065, i suspect RJP63F3 would do there

At a couple of bucks each from UT, I'd take a chance but I do not recommend purely replacing the IGBTs that are shorted and expecting it to then work.

odds are they will simply blow again.

[glen65]

Re: tc-p50S2 10 blink SC troubleshooting

I've had no quality issues although sometimes the leads look a little suspect like it could be fake but touch wood every part I've received has worked and tested similar to what they should be.

Some arrive with pre bent leads which are sometimes in the wrong direction needing careful rebending to install them . Mainly the panasonic IGBTs. Some have a R stamped and they are always bent in the opposite direction to the non R. originally i thought it was an electrical difference but now I think it simply means the leads are pre-bent in the reverse direction as part of the factory process.

I have no evidience to back the theory but no issues.

delivery is slow unless you shell out for DHL etc which adds a good chunk of $$ but if the order was large enough may work cheaper but a good 3 weeks from china to Aust, maybe 4. No idea how transit is to the US, would not surprise me if it was quicker.

They can take a while to compile the order but always well packed and static protected.

i'm confident if you did get fakes they'd sort it out, I expect their intention is to supply good parts but I'm sure they get caught themselves.

hope this helps.

Thanks for the reply,
I asked because I am currently working with a TNPA4844AD SC board
with the following shorted components. 2PG011, RJP4585, RJP6065.
These are obsolete numbers, and I cant seem to find anything to sub these IGBTs.
The sticking point is the current spec. The 2PG011 for example, has a continuous current rating
of 40 amps, (not too much problem there), BUT at the same time it has a
pulse current rating into the 200 amp range. The highest I could find was
about 160. If I cant bring myself to buy the HK semis, I'll just have to bite
the bullet and pay the higher cost from Panasonic.

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

I've looked at UTSOURCE a few times but am concerned about quality.
You seem to have experience with them, have you ever had any trouble
in that department? Also (generally) how long does it take them to ship
an order? Thanks.

I've had no quality issues although sometimes the leads look a little suspect like it could be fake but touch wood every part I've received has worked and tested similar to what they should be.

Some arrive with pre bent leads which are sometimes in the wrong direction needing careful rebending to install them . Mainly the panasonic IGBTs. Some have a R stamped and they are always bent in the opposite direction to the non R. originally i thought it was an electrical difference but now I think it simply means the leads are pre-bent in the reverse direction as part of the factory process.

I have no evidience to back the theory but no issues.

delivery is slow unless you shell out for DHL etc which adds a good chunk of $$ but if the order was large enough may work cheaper but a good 3 weeks from china to Aust, maybe 4. No idea how transit is to the US, would not surprise me if it was quicker.

They can take a while to compile the order but always well packed and static protected.

i'm confident if you did get fakes they'd sort it out, I expect their intention is to supply good parts but I'm sure they get caught themselves.

hope this helps.

[glen65]

Re: tc-p50S2 10 blink SC troubleshooting

post 7 & 14 is all the info and suggestions I can give you.

UTSOURCE i got the bulk from there, there are subs for some of those common parts like the Toshiba logic chips ( eg TI) , voltage regs, signal transistors.

I highlighted parts you could strip from a cheap SS board.

Ebay and local suppliers. RS components here have free post for online purchases for Australia, maybe you have a similar supplier with same deal?

UTSOURCE has a minimum unit cost of $1 so some of those bits are like 20-50c parts.

They also tend to make the prices up sometimes, not unusual to get quoted more than their Ebay listing but I have also been quoted less too.

You will be waiting a while with the $4 post from china.

That's just the way it is.

I've looked at UTSOURCE a few times but am concerned about quality.
You seem to have experience with them, have you ever had any trouble
in that department? Also (generally) how long does it take them to ship
an order? Thanks.

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

post 7 & 14 is all the info and suggestions I can give you.

UTSOURCE i got the bulk from there, there are subs for some of those common parts like the Toshiba logic chips ( eg TI) , voltage regs, signal transistors.

I highlighted parts you could strip from a cheap SS board.

Ebay and local suppliers. RS components here have free post for online purchases for Australia, maybe you have a similar supplier with same deal?

UTSOURCE has a minimum unit cost of $1 so some of those bits are like 20-50c parts.

They also tend to make the prices up sometimes, not unusual to get quoted more than their Ebay listing but I have also been quoted less too.

You will be waiting a while with the $4 post from china.

That's just the way it is.

[allenrw]

Re: tc-p50S2 10 blink SC troubleshooting

So the price and availability of parts is now the problem.
I am having trouble finding all of them and the ones I have found are from different vendors so there are shipping costs added.
A used guaranteed board is about 120 dollars US and SU/SU boards are 12-20 dollars US.
The tv costs 500 dollars US new.
Bottom line is I need a cheaper source for the parts.
Any ideas?

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

The boards were out on the bench connected to the meter only and disconnected from each other.
I tried changing leads some and I don't think the results varied.

Best get fresh ones then, I could'nt think of anything worse if we get that SC going only to kill it with the buffers.

At least you can run that SC up with the bypass in the meantime without them.

[allenrw]

Re: tc-p50S2 10 blink SC troubleshooting

The boards were out on the bench connected to the meter only and disconnected from each other.
I tried changing leads some and I don't think the results varied.

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

Attached are the buffer board measurements

yeah, I'm a little baffled by those. Vscn_F is spot on.

But the others don't match but they all read the same on both boards.

from the few boards I've had a chance to test, at least something generally shows short.

When I tested mine they were removed from the TV. i don't think having them hooked to the panel would matter but a couple of questions.

1 Were they disconnected from the 3 SC connectors/
2. earth screws removed?
3. interconnecting ribbon disconnected between SD & SU boards?
4. try again and reverse the probe polarity and recheck results?

Two figures i could get consistantly were Vfo 1.8Mohms and Vsc_F at 220kohms.

I just found some more results from my brothers TV and that had bad SD,SU,SC.

On that one I have 500-600K on 5V_F on the SD board, 2.3Mohm on SU but both had shorted Vfo (1.8M normally) Vscn_F on both of those dead short.

if you can't get 1.8M or so on the Vfo and 5V_F is still only 100'sKohms then yeah I tend to agree there's enough difference to bail out and find some good ones.

With my brother's TV buffers as they were I got lazy and did not test them assuming they were going to be good like mine.

End result was blowing up a brand new SC.

[allenrw]

Re: tc-p50S2 10 blink SC troubleshooting

Attached are the buffer board measurements

[allenrw]

Re: tc-p50S2 10 blink SC troubleshooting

I'll post the buffer board info tomorrow I hope.

[tw2005]

Re: TC-P50S2 10 blink SC troubleshooting,TNPA5105 repair

Q16401 DG3D5020CSLW TRANSISTOR 1 DG502LW shorted
Q16402 DG3D5020CSLW TRANSISTOR 1 DG502LW shorted

Q16421 B1JAEP000014 TRANSISTOR 1 RJP43F4A shorted
Q16422 B1JAEP000014 TRANSISTOR 1 RJP43F4A shorted

Q16521 B1HFPFA00001 TRANSISTOR CPH5524-TL-E not sure if it was shorted but will replace anyhow ((Pins 2-3 & 1-5 , 2-3Mohms from memory(I'm not shouting))
IC16521 C0ZBZ0001708 IC M81737FP again not sure if it was shorted but will replace anyhow (Good idea, did you check the Vcc-gnd resistance, how did P15V resistance right after this was removed? If still funny,NAND GATE cct, IC16691,Q16647 last board both those were failed)
Q16661 B1JAER000010 TRANSISTOR 1 RJP63F3A shorted(every board this was failed)

IC16771 C0CBADC00072 IC 1 78L05L, TA78L05F shorted(shorted out of cct too? 1 of 3 boards this was bad)

Q16701 B1ADCN000007 TRANSISTOR 1 MMBTA92 shorted
Q16702 B1ABCF000231 TRANSISTOR 1 2PD601ART,215, 2SD0601A0L shorted(every board this was failed)

IC16773 C0JBAB000715 IC 1 Toshiba TC7SH14F shorted(every board this was failed)

C16708 F1H1H104A970 C 0.1UF, K, 50V, lost during testing, gawd these things are small and hard to hold!


IC16501 C0ZBZ0001708 IC M81737FP not sure if it was shorted but will replace anyhow

IC16661 C0BBBA000024 NJM2903V(TE1) , removing this cleared a ~500ohm path 16V_F to VAD (very surprised to see this on the list, no problems on mine but did remove and compare to a known good one, wish I had not with the soldering)

R16900 D0GB103JA057 M 10K OHM J 1/10W , tested 3.9k in circuit supposed to be 10k(so out of cct it was? It all ties in cct ,part of which heads down to shorted Q701,702,IC773 so that may be the real issue?)

Green part numbers are also on that SS board I mentioned for scavanging.

M81737FP Qty 1
NJM2903 Qty 1
CPH5524 qty 5
F1H1H104A970 0.1UF, Qty 3
D0GB103JA057, M 10K OHM J 1/10W Qty 3

My very first repaired board, my post #22 is very close to the fault profile of your board.

[tw2005]

Re: tc-p50S2 10 blink SC troubleshooting

Do me a favour and list what you did get on the buffer boards for resistance.

[allenrw]

Re: tc-p50S2 10 blink SC troubleshooting

To recap
Q16401 shorted
Q16402 shorted
Q16421 shorted
Q16422 shorted
Q16521 not sure if it was shorted but will replace anyhow
IC16521 again not sure if it was shorted but will replace anyhow
Q16661 shorted
IC16771 shorted
Q16701 shorted
IC16773 shorted
IC16501 not sure if it was shorted but will replace anyhow
Q16702 shorted
IC16661 removing this cleared a ~500ohm path 16V_F to VAD
C16708 lost during testing, gawd these things are small and hard to hold!
R16900 tested 3.9k in circuit supposed to be 10k
I test a number of capacitors that had 200 to 500 mF in circuit and were correct out of circuit. I started not pulling these caps if they weren't shorted, I didn't find a single shorted cap.
I ohms, diode or capacitance tested every device that was connected to the bad parts and found nothing else.
I used TW2005's SU and SD readings for his cards (different from mine some) and found enough differences to make me consider getting new/used ones (they are pretty cheap).
So I will most likely order all these parts and see if it goes.
I have considered applying, with current monitoring/limiting, 15 and 5 volts to SC20 and see what happens before giving it an installed full power test.
The question that still remains is what caused all this? I haven't had time to see what the common thread may be.
Anyhow the beat goes on, stayed tuned for the continuing saga.
TW2005 thanks again for your input, I probably wouldn't have gone this far without the direction you provided.