Panasonic th-p50v20a fhd plasma-4 blinks

[tw2005]

I thought I'd throw this out there for comments.

I'm working on this PANASONIC TH-P50V20A FHD PLASMA-4 BLINKS. Goes to 4 blinks straight away.Checked the Vsus and nothing there, not even a rise.

So I removed the SC board and the set fired up, voltages Ok, shutsdown, 7 blinks which seems pretty normal.

Checked over the SC nothing visually obvious then checked out the transistors and found about 7 items dead short on different heatsinks.

Did not find any shorts on the SU/SD.

Are the SC boards a common problem with these later PANASONIC Plasma sets?

[CHRISS]

I thought I'd throw this out there for comments.

I'm working on this PANASONIC TH-P50V20A FHD PLASMA-4 BLINKS. Goes to 4 blinks straight away.Checked the Vsus and nothing there, not even a rise.

So I removed the SC board and the set fired up, voltages Ok, shutsdown, 7 blinks which seems pretty normal.

Checked over the SC nothing visually obvious then checked out the transistors and found about 7 items dead short on different heatsinks.

Did not find any shorts on the SU/SD.

Are the SC boards a common problem with these later PANASONIC Plasma sets?

Hi tw2005
Yes SC common i have had it plenty of times the 7 flash mean no SU SD drive sig cos SC disconnected
PCB no, TNPA5081- 1 SC part no TXNSC11QEK50

.

[tw2005]

Hi tw2005
Yes SC common i have had it plenty of times the 7 flash mean no SU SD drive sig cos SC disconnected
PCB no, TNPA5081- 1 SC part no TXNSC11QEK50

.

Thanks Chriss. I realise you're an Authorised repairer but do you know much about all the different revisions of boards Panasonics produces.

To clarify what I'm curious about is you find various models which have the same plasma panel version but may have different SC board rev and part numbers.



As you've highlighted the board is TNPA5081 rev AF , Part TXNSC11QEK50. they also use the same PCB TNPA5081 in 42" as well but with some component differences.

Are there compatability issues using a different boards because from what I can see all the 50" SC boards look the same at a glance.

Thanks

[CHRISS]

Hi tw2005

the part no i gave you was out of the service manual and i just check on Panasonic E PAN and this is what i got
Description SC PCB TH-P50V20A
Bar Code (EAN) TXNSC11QEK50
so the 42 is not the same as the 50 but the printed pcb TNPA5081 will be similar

ps if you need a copy of the manual i can upload it for you

[tw2005]

Hi tw2005

the part no i gave you was out of the service manual and i just check on Panasonic E PAN and this is what i got
Description SC PCB TH-P50V20A
Bar Code (EAN) TXNSC11QEK50
so the 42 is not the same as the 50 but the printed pcb TNPA5081 will be similar

ps if you need a copy of the manual i can upload it for you

Cheers, that would be handy to add to my collection. If you have the time.

Yeah I realise the 42 can't be used but curious about the different revisions of the 50" model.

I've got a couple of SC boards coming but different revision so will have a go and post what happens.

I just hope I get more life out of it than the first board. Panasonic one of those brands you get use to being very reliable.

Thanks

[CHRISS]

Cheers, that would be handy to add to my collection. If you have the time.

Yeah I realise the 42 can't be used but curious about the different revisions of the 50" model.

I've got a couple of SC boards coming but different revision so will have a go and post what happens.

I just hope I get more life out of it than the first board. Panasonic one of those brands you get use to being very reliable.

Thanks

service manual TH-P50V20A
The was not an alternative part no for the SC pcb so hope the different revision don’t blow the upper and lower cos they are matched together
Will be good to see how you go cos I have never tried it b4

[tw2005]

service manual TH-P50V20A
The was not an alternative part no for the SC pcb so hope the different revision don’t blow the upper and lower cos they are matched together
Will be good to see how you go cos I have never tried it b4

Well there's something I never considered. I'm feeling lucky but don't worry I'll be posting the results when I do it. It's easier to experiment when you own the TV your playing with.

[iwacelect]

Check pin 9 of connector p7, if over 3V before shutdown then psu, if not then its the a pcb

4 blinks is psu in my manual

[CHRISS]

Check pin 9 of connector p7, if over 3V before shutdown then psu, if not then its the a pcb

4 blinks is psu in my manual

Hi iwacelect
4 flash yes it say psu in manual but if sc transistors shorted will give wrong code as psu fault, so when tw2005 disconnected the sc pcb and the flash change to 7 then power supply should be ok ,

[iwacelect]

My point is the psu could be buggered as well as SC, seen SC bugger psu's before

Have you tried an SC yet TW?

[tw2005]

My point is the psu could be buggered as well as SC, seen SC bugger psu's before

Have you tried an SC yet TW?

No, waiting for one to arrive.

Vsus looked good with the SC removed.

[iwacelect]

No, waiting for one to arrive.

Vsus looked good with the SC removed.

4 flash is an over voltage detect, so may have something to do with SC, but being short wouldn't have expected an "over voltage"

[tw2005]

Regulation issues with any of the voltages from the power supply.
��
If PFC goes over 470V (±50V) or below 165V (±20V)
��
If Vsusgoes over 240V (±10V)
��
If Vdagoes above 67V (±4V) or below 28V (±4V)
��
If there’s an over current condition at the P15V line

I'll check everything thoroughly before I install it just in caes

[tw2005]

Well boards arrived and it looks like a pig in a poke. TV still not working and now SOS6.

I guess a lost gamble. Hard to believe 2 SC board failures but replacement has no shorted fets at least.

Followed the recommended fault tree, 15V & 5V supplied at SC board. Isolated SC20 that feeds to the "A" board and C10 on the "C1" board and faults goes to SOS8.

According to the Tree, end result Replace SC board.

I'm thinking maybe component level canibalisation and getting one board good.

Any suggestions?

Still have another board coming from different vendor.

These are different revisions to my original but I still think they'll work.

Original was AF, just Tried an AP and I think the next could be AW.

Stay tuned for more giggles at my attempt to fix this.

[tw2005]

Well, up to my usual dodgey tricks. Just disabled SOS6 return to the "A" board and she's up and running. Service manual seems to have little or no voltage info.

i'll measure VAD which to chassis was nearly 200V. I may have a quick look at my P42X14A fault finding and see how it compares.

These SC boards must have some crazy bit failing to be able to still work and not burn up.

false detect?

OH, and I've earthed the SOS6 return which was sending about 4.4V. Will this destroy anything?

[tw2005]

Panel Time 2530Hrs.

VAD to chassis gnd -199V.
VAD to VFgnd -70V

TPVSCN to chassis -53V
TPVSCN to VAD 147V

VSUS 203.8V
TPVe 134.9V


This is so different to what I'm used to. No panel sticker for the voltages either?

Need help.

[tw2005]

Ok, It's all sorted now and I reckon this is a good one to save somewhere because I hate replacing boards just because of a $0.20 part.

Just to re-cap.
SOS4 on front panel, PSU SOS
VSUS =0V,
Removed SC board, VSUS 204V, Shutdown , Now SOS7,
Checked original SC board, multiple FETs,IGBT & Diodes dead short killing VSUS.

Ordered replacement SC, supposedly New from smashed TV.
Installed, still not working, now SOS6. Followed SC board tests and isolation confirming SC board faulty.

Disabled SOS6 return to "A" board, TV fired up, checked voltages, appear ok, picture appears ok.
Green LED D583 (D16583) not illuminating. fault tree says replace SC if LED not lit.

Traced SOS6 error detect at IC581(IC16581), measured 107V on anode side of LED, 0V on cathode which is what the comparator uses to check. LED is open cct.

60-151V is spec so 107V is good.

Jumpered D583 on original board across dead D583 on replacement board, LED illuminated, SOS6 return enabled and TV now functioning correctly , no more SOS6!


Revision of replacement TNPA5081 is AP, original was AF. Working just fine.

[tw2005]

British board arrived. TNPA5081 Rev: AW TXNSC11VEK50 WORKS perfectly fine too. Out of TX-P50G20B

Check out my cool orange 3mm LED sub for the open cct chip LED. (all i could salvage )

[tw2005]

Just a little addition to this. i never convinced myself whether the SD/SU boards were 100% so did not risk them and did a full SC/SD/SU swap.
Anyway, talked my brother to get the same TV broken with identical failure symptoms, same SC failure but I fixed it enroute to the NT and did not have the resources to do a full check and chanced just the SC swap.
Went from 4 to 7 blink. SU/SD bypass allowed the TV to turn on but stupidly I could not believe the buffers were bad so did a reseat of everything and Poof. One very dead, quite new SC board. Survived one power up, not the next.

Used my last SC and only buffer set and once again all good. This one had 3300hrs

So now I'm thinking it's actually the buffers in these TVs not the SC which are duds. All 3 dead SC boards ended up which these dead short D482,Q452,Q403,Q402,Q421,Q660,Q661.

If it's possible to get these parts I'd be interested in their cost if someone can get them for me. I'd like to have a go and see if I can repair these 2 boards for spares if not too expensive.

D482 RFN25 B0FACP000003
Q452 45G128 B1JAEP000012
Q403 DG502LW DG3D5020CSLW
Q402 DG502LW DG3D5020CSLW
Q421 DG402RP DG3D4020CSRP
Q660 R5007 B1CERR000042
Q661 RJP63F4A B1JAER000010

[hansron]

Hi Chriss.

Reading an earlier post, you checked the SU & SD for shorts.
Before ordering the SC board, I need to do this.
4 blinks found SC shorted (TNP A5081)
Having trouble finding the earth ref on each boards.
Circuit would be useful or can you give some instruction?

Many thanks