TNPA5105 rebuild

[tw2005]

Re: TNPA5105 rebuild

Yup--Thats what it was, Different make 78L05 reg...

I checked a new unused 78L05 chip, O/P to Gnd, = 5.1K I'm guessing this must be the internal pot divider for the feedback....

Now--Finished up re-populating the heatsinks, gave the board a good going-over for any other issues and all set to go.....

Or so I thought.

Due to a massive brain-fart and Monumental Cock-Up on the SUS board rememberance Front, Ive found that the set I intended to use this board in has a Completely Different SC-- In fact, Its Not Even an SC, but an SN! A TNPA5066 to be exact.

Dunno what had convinced me that this set used 5105....

So--Ive got a rebuilt Untested 5105 and a dead 5066..... Doh!

I'm thinking I could test this 5105 in the 42G20 that I buggered up the 5081 in, as I did an opposite swap using a 5081 in place of a 5105. A job for Sat Afternoon when the place is quiet.......

would work as a mule but will the Sc20 ribbon make it? 5105 board is probably a good inch narrower which means the ribbon will need to go that bit further

[Alastair E]

Re: TNPA5105 rebuild

Ah--Good you mentioned that!

I have a cunning plan--Grab that cheapo Argos special FHD 42" outta the garage and use the correct ribbon from that. The garage set was robbed for parts before I got it,(SN/SC PSU, SS etc Main is still there) but pretty sure the ribbon is still there too Only kept it as the panel looked good and with hope the spares may turn up...

[Alastair E]

Re: TNPA5105 rebuild

I rebuilt the Original SC 5105 from this 50S21B, and tried it out.

I used the bulb in series with Vs and checked buffers from VFO to output pins.
--Ended up with Q661 short again and Q621 short. Bulb remained dark, after just a slight glow initially (guessed charging the SC caps--Or maybe the IGBT's dying....)

There was no '0' VAD and VSCN was 140V, both with ref to chassis

I'm suspecting Ive a buggered buffer--Need to check more closely. This set is one of those 'Cheapos' with no heatsinks on the buffer-chips. I think the bulb saved a lot of silicon in this case, Only two (apparently) IGBT's dead.
Q702, Q701 read OK....

For future reference, The supply out of IC771--Without the Reg on the board reads 100K one way and climbs to 1M the other--when all the small stuff like IC773, D702, Q702 and Transoptor etc, are good...

[ReeceyBurger123]

Re: TNPA5105 rebuild

So you think possibly a bad buffer can cause this ? If so going to check mine when I get the SC on order.

[Alastair E]

Re: TNPA5105 rebuild

Yup-- Apparently a dead buffer will kill the SC...
--Its not so much the usual shorts to the o/p pins but the small signal and the supplies to the buffers themselves--Probably lowers/kills the 5v and 16V rails which leads to the IGBT's being turned on all wrong...

There's a test procedure on the 5081 thread, and done by TW2005--I think--that describes what to check and expected good readings....

[ReeceyBurger123]

Re: TNPA5105 rebuild

Ok cheers, I have a buffer which will work from that S10B set so if my buffer is shot I will change them over. Will test it before ordering SC.

[tw2005]

Re: TNPA5105 rebuild

I rebuilt the Original SC 5105 from this 50S21B, and tried it out.

I used the bulb in series with Vs and checked buffers from VFO to output pins.
--Ended up with Q661 short again and Q621 short. Bulb remained dark, after just a slight glow initially (guessed charging the SC caps--Or maybe the IGBT's dying....)

There was no '0' VAD and VSCN was 140V, both with ref to chassis

I'm suspecting Ive a buggered buffer--Need to check more closely. This set is one of those 'Cheapos' with no heatsinks on the buffer-chips. I think the bulb saved a lot of silicon in this case, Only two (apparently) IGBT's dead.
Q702, Q701 read OK....

For future reference, The supply out of IC771--Without the Reg on the board reads 100K one way and climbs to 1M the other--when all the small stuff like IC773, D702, Q702 and Transoptor etc, are good...

Did you ever get the 5105 going?

Just did mine finally, I missed a few things like a couple of smd resistors which were blown or out of tolerance around the drive cct Q551.

running it in the V20 which is a struggle with the sc20 ribbon too short

[Alastair E]

Re: TNPA5105 rebuild

Nah--Never got back to it. Ive still got it, but had a 42" 5105 from a smashed set that I swapped all the ERC parts over from.

--That made that 50" set all work fine, tested it for some days, then it went into shop--Didn't last long there (50" never do), and haven't seen it since..

Ive got a few SC boards of various types--in various states of blowed-upness, which I'll hang onto for the future...

[tw2005]

Re: TNPA5105 rebuild

Did you ever get the 5105 going?

Just did mine finally, I missed a few things like a couple of smd resistors which were blown or out of tolerance around the drive cct Q551.

running it in the V20 which is a struggle with the sc20 ribbon too short

So here's a list of what i replaced on this board.

Q661,Q660,Q401,Q402,D642,Q421,Q422,IC521,R551,Q551,Q451,D482,R451

It's interesting on this IC773,Q701,Q702,Q818 are ok. But more damage around ic521.

I've also used RJP56F4A in this for the DG502

there is very little difference between this and the 5081

also a 5105 board will directly bolt into my V20 however the cabling is too short, but a 5081 would also then bolt into the S2 or U2 series and cabling would be too long which is not really an issue.

[mann935]

Re: TNPA5105 rebuild

Well there is plenty of stuff already on TNPA5105 rebuilding . I wish to share here my problem of removing and reinserting SMD parts , and I got around this using the flat heater pads that ladies use to straighten their hair . Placing those heater pads under circuit board helps removal and adding SMD parts .

[HJKLP]

Re: TNPA5105 rebuild

Repaired Panasonic TX-PR42U20 GPF13DE BLOCK TNPA5105.
Struck put
* Q661 (RJP63F3A), RJP63K2
Q401, Q402 (DG502LW), RJH30E2
Q422 (RJP43F4A). RJH30E2
And replaced the resistor R422, the resistance increased by 1 ohm.

Repair was limited to replacing only these elements.
During the initial inspection, it was found that the malfunction arose from behind the ring crack of the output of one of the transistors.

[andyb1712]

Re: TNPA5105 rebuild

I recently acquired a TX-P50U20B stuck in standby with 10 flash code.

The previous owner had it checked at a repair centre for his house insurance and it was diagnosed as Y-SUS SC board failure. Due to the repair timescale he decided to buy a new tv.

I disconnected the SC from SD/SU and shorted SC50. The flash code changed to 7 and the set remained in standby, so I ordered a 15 part repair kit from eBay and proceeded to replace the blown parts.

On power up there was a loud crack after the main relay clicked and the set returned to standby with 10 flash code. Appears I missed something on my first attempt and destroyed my new components, plus some others too.

The 50" AB variant of this board is quite scarce but there are plenty of AD variants from the 42" model. I've made some comparisons using service manuals and online photos and from what I can see the AB variant has 2 additional capacitors and some big inductors in different locations. Perhaps some other parts too?

Has anyone successfully converted an AD variant for use in a 50" model as this looks a cheaper option than throwing more new parts onto my blown AB one?

I've done the cold checks on the SU/SD boards and they look good but next time I'll definitely power up with them disconnected first. Does this need to be done with the four bolts removed as well as the 3 inter connects as this is not mentioned in the service manual?

[andyb1712]

Re: TNPA5105 rebuild

For anyone following this thread...

I acquired a TNPA5105 AD (42") and fitted C415, C631, L401, L402, L412 and L413 from my AB (50") variant, removing L401, L403, L411 and L412 from the new board in the process.

The board works fine in the 50" set as a result and at £30 was cheaper than throwing more new components at the original one with the risk of it going bang again.

[budwich]

Re: TNPA5105 rebuild

its a good find / alternative. I have been wondering about the "versioning" on my tcp50s30 as the "AM" that it came with (damaged / shorted) is relatively expensive verses versions "AF" and "AJ" which look similar if not the same. So maybe your "experiment" can work for other similar "challenges".

[andyb1712]

Re: TNPA5105 rebuild

Looking at the TNPA5105 there are markings on the board which indicate the capacitors and inductors that should be fitted for each size screen, 42, 46 or 50.

Not sure if this the same on other models as I've not worked on that many.

It's certainly cheaper to buy a working board from a smaller screen model and convert it for the 50 than keep throwing money at trying to repair the original board.

I've given up after 2 failed attempts to fix my original as I've now spent far more than the board is worth on parts. There's also the question mark over fake or recycled parts from China that are sold as new.

My second attempt was after a very thorough read of the TNPA5105 and 5081 repair threads and repeated checking of all parts before applying power. It still went pop again...

At least I have the 'converted' board and the TV is working with that.

[andyb1712]

Re: TNPA5105 rebuild

Third and final attempt at a component level repair of my original TNPA5105 and I finally got it working... for all of about 5 minutes. Then there was a loud bang and a bug chunk of IGBT shot out the back of the set and it shut to standby.

I was very thorough with this rebuild and for the 5 minutes it was running, the picture was fine so I can only assume fake components (again) that aren't up to the job. I'll stick to board replacement from now on with these as it's quicker and cheaper!