TNPA5066 Rebuild, Pan. 42C2B

[Alastair E]

Due to a bit of a cock-up, Ive found I need to rebuild a TNPA5066.

This is one of the combo buffer/SC boards known as the 'SN' type. The set also uses an ERC circuit fully contained on the SN board, so any problems with the SS board can cause the SN board to destruct.

In this 42C2B the SS board had 4 shorted IGBT's, 30E4 that I replaced with DG301 as I had these to hand, should be adequate for the job (330V, 250A I/p) and also the two transistor driver pairs, although these drivers checked OK.

Following the diagnostic procedure pioneered by TW2005 for the TNPA5081 and similar 5105 boards we checked out this 5066

This SN board had the following short--

Q661
Q621
Q421
D481
Q702

Seeing that the numbering of the associated parts is much the same through the Panasonic SC/SN range made this a lot easier.

I replaced Q701, Q702, IC771, IC773, Q818 which are associated with the driving of Q661 any issues with this lot will cause Q661 to fail at turn-on and ruin lots more too.

In addition to these, I replaced the Transistor Driver pairs Q521, Q551, Q762, which are associated with the dead IGBT's. although they didnt test as short.

Checked over the board, All looked good so board refitted without panel-tabs connected and I used my special home-made SC to P board VSUS main power connecting-lead with integral 150W lamp from SC2 to the PSU as a current-limiter, object being if all is well set will work, but have a bit of a dim cruddy picture, but If there's still problems, may prevent excessive destruction at turn-on.

Set was fired up. Lamp slightly glowed at turn-on but then remained dark, the green MID/ERC LED near IC521 came on then got slightly brighter, relay click off and 7 blink....

Checks on all heatsink parts indicated all was still OK--Apart from a leak of 390 odd ohm across E-C of Q451. Transistor pulled and wasn't leaky. The Diode, D451 wired across E-C Q451 shows the leak...

At least it didn't self destruct on turn-on so something to be glad about!

Pretty sure I would have spotted this leaky diode before--so not sure whats happened here. Maybe it was terminally damaged initially, but showed OK and died on start-up after repairs....
Will replace that diode tomorrow and further check this SN and the SS before continuing...

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

So--Hmm, That went well....

Not!

Replaced the diode, D451 with exact same from another TNPA5066 thats also faulty. This diode tested flawless.

Tried the board in set after going over it yet again, checked Buffers yet again...
Everything connected up inc panel-tabs etc.

7 Blink, Dark bulb, OK fine.

Decided to disconnect the VSUS supply to SS board....

Tried again. There was a almost silent 'tick' and my safety-bulb came to full brightness, relay on PSU cut out just as I also pulled the plug...

Now Ive got the ever popular destruction of Q661 now being short Again, Glad I bought a pile of RJP63F4A.....

Q401 Q402 and D401 also showing short--Prolly only one of these parts--they are paralleled.

Similarly, Q421 and D421.

Q818 shows 60 ohm D-S, Q701, Q702 Seem OK as well as IC773 but there's a 700 ohm reading on IC771 (VAD+5 reg) output. This was previous to This failure 2.2K....

Looking at the arrangement with the SS being merely square-wave switching, and all the ERC gear on the SN in these sets I may have killed this board by removing the VSUS to the SS, without also removing the ERC return lines from SS then trying to fire it up to see what blinks I got....
--Idea being there was no source of supply to the SS, therefore the SUS side of the SN was supplying back via the ERC to the SS--Dunno, Buggered it anyway!

Oh dear. Got pissed at it, and shoved it aside in favour of a Sams, 50B450 Need to get something through the W/S today--At least That went OK...

Back to this 5066 tomorrow with clearer head....

[ReeceyBurger123]

Re: TNPA5066 Rebuild, Pan. 42C2B

Dont give up buddy sure you can do it

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

So--Hmm, That went well....

Not!

Replaced the diode, D451 with exact same from another TNPA5066 thats also faulty. This diode tested flawless.

Tried the board in set after going over it yet again, checked Buffers yet again...
Everything connected up inc panel-tabs etc.

7 Blink, Dark bulb, OK fine.

Decided to disconnect the VSUS supply to SS board....

Tried again. There was a almost silent 'tick' and my safety-bulb came to full brightness, relay on PSU cut out just as I also pulled the plug...

Now Ive got the ever popular destruction of Q661 now being short Again, Glad I bought a pile of RJP63F4A.....

Q401 Q402 and D401 also showing short--Prolly only one of these parts--they are paralleled.

Similarly, Q421 and D421.

Q818 shows 60 ohm D-S, Q701, Q702 Seem OK as well as IC773 but there's a 700 ohm reading on IC771 (VAD+5 reg) output. This was previous to This failure 2.2K....

Looking at the arrangement with the SS being merely square-wave switching, and all the ERC gear on the SN in these sets I may have killed this board by removing the VSUS to the SS, without also removing the ERC return lines from SS then trying to fire it up to see what blinks I got....
--Idea being there was no source of supply to the SS, therefore the SUS side of the SN was supplying back via the ERC to the SS--Dunno, Buggered it anyway!

Oh dear. Got pissed at it, and shoved it aside in favour of a Sams, 50B450 Need to get something through the W/S today--At least That went OK...

Back to this 5066 tomorrow with clearer head....

Yeah, I failed first go and as I was reading first thought were messing with the SS since they are connected to each other in these.

The 42x20a(same deal) I remember initially bad SS, fixed that , then other issues and somewhere along the journey I shot the SN in the arse mucking around removing leads and running it, was at the ERC side and a DG501 with smd diode shorted.

And then when it was good, my SS let go after 4 days and took out the Sn again!

there is a point where the challenge and fun evaporates, that was it.

So for me I still have those for repair but I've let it go and moved on as I have a complete SN/SS set for it (originals) and it has been fine ever since. (letting the sleeping dog lay)

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Cant believe the amount of Time these Pan SUS boards have taken up for me over the last week or two...
What with research (Mostly reading, and re-reading through your excellent 5081 etc threads) as well as the hands-on messing with them!

My problem is I need to keep things moving along, get sets through the door so Problem Child like this one get regularly put on hold....

We see what sort of mess I can make tomorrow....

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

Cant believe the amount of Time these Pan SUS boards have taken up for me over the last week or two...
What with research (Mostly reading, and re-reading through your excellent 5081 etc threads) as well as the hands-on messing with them!

My problem is I need to keep things moving along, get sets through the door so Problem Child like this one get regularly put on hold....

We see what sort of mess I can make tomorrow....

cheers, thanks. I like to think it has unlocked a few doors although going back through it there is also some wrong information in there initially. So far I've managed to pull off fixing 4782, 5066, 5081, 5351 & 5335 boards and the 5072 SS.

The more you do the more you learn and nail them first go. I got to that stage with the 5081 quick as the failures were very consistent, you just learn to just replace whole sections, in the end the few bucks you may save is well spent not having to start all over.

The 2 5335 boards I have will be my next challenge as 1 has already let go doing a minimalist 3 part repair, damn China and it's New Year holidays. missed the shipment deadline by a day so all my parts are sitting for a month then it takes a good 2-3 weeks to get here, driving me

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

SUCCESS!--At Bloody Last!

Here is how it went--

Pulled Q661, which as short.

Pulled Q701 and Q702 which were not.

Pulled Q818, 60 ohm leak, D-S.

Pulled IC773 no apparent short

Pulled IC771 no apparent short.

Pulled D701 --Odd readings, 490 on diode-test, 20K leak on ohms.
Replaced with same type from other board occupying D702 position that read 700 odd diode and O/C on ohms.

All the above replaced with new again, except D701 that was s/h but good.

Pulled Q421 which was short and also short to gate.

Pulled Q521 which was not.

Pulled IC521 (drives Q421 via Q521) Unable to test.
--All these replaced with new.

Pulled Q401 and Q402. One was short and leaky to gate, the other was OK.

Pulled Q501 which was not.

Pulled IC501 (Drives Q401 and Q402 via Q501) Unable to test.
--All these replaced with new.

Board checked, no apparent problems. 2.4K reading on IC771 output, Installed again with The Bulb and fired up.
--LED in ERC came on for 5 seconds, then The Bulb flashed momentarily, again off with relay-click.
Tried again--No life except relay-click and 4-blink.

Checked all heatsink parts of 5066--Still Good.

Checked VSUS plug of SS board--Short.

Pulled SS board, all four DG302 S/C.

Grabbed a TNPA5072 from a 37" C2B with dodgy mainboard and int 8 blink,--but the tab-plugs don't line up with 42" panel-tabs, board looks identical otherwise.

Bugger this,-- swapped over tab connectors...

Tried Yet Again....
Usual double click from PSU, Green LED on 5066 came on----And Stayed On. The Bulb still dark and stayed dark.

Stood looking at it for some seconds, then noticed flashing from corner....
--A part of the panel is exposed where the tip-off is, It was Analogue Snow on the screen leaking through from the backside of the glass.....

Plugged in antenna, lifted set up and lent it against an incredibly scratched 42B450, grabbed a Pan remote and pressed 'TV' button....

Ireland Vs Wales Rugby match came on--Perfect picture--We were loosing....

For a larf, I turned Brightness and Contrast up full--To see what effect this would have on The Bulb.

I'm thinking the failure to work on first attempt was D701 leak....

--Have to find exactly What D701 is and get some....

--The picture was completely normal, no expected mal-discharge because lower than normal VSUS due to The Bulb,--just an overly bright picture--and The Bulb still remained completely dark, Not even the slightest glow....

Left it run for half-hour,--Then I went home.....

I expect had I not used The Bulb in the VSUS supply to the 5066, The SS board would have blown it all up again, thankfully it was only the SS that suffered.

Now Ive got that Other one to do, Yup--Another TNPA5066, but need some --More-- M81737FP, I'm sure The Bulb will feature in that one's testing repairs too........

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Right--

Looking at D701/2 and not being easily able to get the originals, Ive come up with this--

75V 200mA, 4ns diode in same package size. Its a MMDL914T1G 'ONN Semi' part.

The diode D701 (under normal operation) would 'see' only around 5.7V, as the diode, D702 Clamps the Base of Q702 to the 5V rail...

A 75V rated diode while 10V down on the original type 'MA2J11100L' should make little/no difference in this application.
I chose a Silicon Fast Diode rather than Shottkey type as this will match the 0.7 ish Volt forward-volts drop of the original, that I assume is also Silicon...

Forgot to mention that the heatsinked Diode, D481 I replaced with a IXYS part,--DSEP29-06B, Soft Recovery Diode, 600V 30A, 30ns, 2-Pin TO-220AC, and a heatsink-washer, as I had no RFUS20 type and I aint gonna wait for UTsource to get their act together.....

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Well--After blowing it all up again due to dodgy VSUS cable, Ive rebuilt this board Again.

Now I have 7-blink, nothing blows, just 7-blink.

VAD is -190 odd, but VSCAN is only 45. (Could be -45 had meter reversed as used clamp on test-point, cant recall...)

I'm suspecting there's a buffer issue now too dragging down VFO--VSCAN-F and then VSCAN....
(REALLY wish they Wouldn't change the terms over the space of the board--Just because there's a Diode on the line)

I put The Bulb (15W, 240V) in series with Q661--Just in case, but it stays dark.

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Progress....Sorta.

I have that second board, so fully rebuilt all the usual suspects.
Fitting this again with a 15W bulb on Q661 collector--I have same 7 blink and No VSCN.

Fitting Q661 as intended correctly I have still got No VSCN but set remains on with mal-discharge spotty picture...

--So Using a Bulb (360 odd ohm, 15W 240V) in series with Q661 stops set running and gives 7-Blink.

--Will try with a bigger bulb when Ive got this VSCN issue sorted, purely to find if one can be used and allow set to run to prevent blow-up type failures during fault-finding a persistent blower-upper...

Replaced VSCN gen chip IC786 which does have supply from VSUS via a diode, still no VSCN, lifted D859 isolating the buffer from VSCN supply, still no VSCN.
VSCN Generator obviously not running, but Dunno why....

There's two optos involved with it, One is probably the F/B loop--the other I'm guessing a control, thats also all wrapped up with the optos in the VAD gen circuit--which is working and making -180 odd VAD

Checked many parts around/in the VSCN gen circuit, cant find fault with any of 'em.

VSCN is currently Minus 45V hence the Orrible mal-discharge picture, I'm guessing it should be Plus 150 odd--This is the same with Both these TNPA5066 boards...

--Anyone have any clue as to Whats going on with this...?

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Hmm........

Just spent a couple of hours reading back posts on TNPA5066...

A few list after blow up/repair and just a fault--some 7-blink, a Minus 45V VSCN, but No One has Ever come back to say What Cured It!

Odd that I don't have a 7-blink, as the VSCN is also monitored...

I have found the voltage for VSCN should be Plus 140ish...

So--A Known Issue with these--and no info on a cure....

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

I'm somewhat confused with post#10.

All the way through it, No Vscn, No Vscn, No Vscn then out of the blue

VSCN is currently Minus 45V with nothing reported as to contributing to this value so I'm assuming you had -45V all along??

They give less info on values in the manuals but if you went back a year they state Vscn = Vad +145v.

As a rough guide that leaves Vad you report as -180 odd volts + 145V , maybe -40V as the result.

Your -45V could be in the ballpark.

So, i will pop the back off my X20 and have a probe for you

When you say

"This is the same with Both these TNPA5066 boards..." are you referring to the maldischarge or the -45v or both ?

Any pictures of the problem?

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

Vsus 193v
Vscn -43.8V (gnd as ref)
TPSN1 25.4v
Vda 55.3v
VAD -190v

TPSS1 102V
Ve 125.3V

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Ah--OK--So I'm an idiot!

For some reason I had the idea VSCN was supposed to be plus 140V...

Mine (Ref to deck) is -45, (hence me saying no VSCN, as it was neg) --So looks as though -45ish ref your set is correct--Thanks for checking for me....

Mal-discharge pic--I'm guessing in light of this new info--SS could be suspect...

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

Ah--OK--So I'm an idiot!

For some reason I had the idea VSCN was supposed to be plus 140V...

Mine (Ref to deck) is -45, (hence me saying no VSCN, as it was neg) --So looks as though -45ish ref your set is correct--Thanks for checking for me....

Mal-discharge pic--I'm guessing in light of this new info--SS could be suspect...

I think if VAD was the ref it would read that? But I think the clue is if it's not tripping the SOS7 then the voltages are within the thresholds.

Could be SS , just have a sticky at my old TH-P42X20A thread because all the maldischarge issues i had was and a missing resistor. has the SS been touched?

If you get it into service mode and run through test patterns, do any look normal like the small white box and black surround?

How's the camera?

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Ive modded a 37" SS by moving the tab connectors--Otherwise untouched. It was in set when I blew the SN due to that cursed VSUS lead...

It doesnt have any apparent shorts present...

Cameras--Well, Set is in work--no internet--I work in shipping-container in recycling-yard...
Will try the test-patterns and see...

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

Just a few to look at, bad SS or actually 1/2 the signal not being processed at the SS.

[tw2005]

Re: TNPA5066 Rebuild, Pan. 42C2B

Ive modded a 37" SS by moving the tab connectors--Otherwise untouched. It was in set when I blew the SN due to that cursed VSUS lead...

It doesnt have any apparent shorts present...

Cameras--Well, Set is in work--no internet--I work in shipping-container in recycling-yard...
Will try the test-patterns and see...

An image of that shipping container would be gold. I bet it has an antenna mounted to it. Any chance it's climate controlled

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

Aye--Looks much the same--Maybe bit darker, but same artifacts...

I do have another SS--But its history is also questionable--Came from the set with the second dead SN, it also shows no shorts apparent....

I do feel such a plumb looking for that VSCN--when it was OK all along!

[Alastair E]

Re: TNPA5066 Rebuild, Pan. 42C2B

An image of that shipping container would be gold. I bet it has an antenna mounted to it. Any chance it's climate controlled

Superb air-con, you regulate by opening the doors!

Yup Antenna mounted on the roof corner. My 'Tin-Box' as I call it is in a row with some others...

I'll take some pics today