TC-P50VT20 10 Blink Code

[Katzat]

Gentlemen, I hope someone can help me. My Panasonic TC-P50VT20 developed the 10 blink code. My kids told me that the TV failed to turn on a couple times on the first try, but came on after a second try a couple times (this is hearsay that I cannot confirm at this time). When I looked at the set after it was no longer turning on, the LED was issuing the 10 Blink code.

I have the Technical Guide and the Service Manual. I'm an electrical engineer, but my understanding of electronics is limited to theory and I haven't really messed much with electronics at the component level since engineering school 30 years ago. I'm slow at best with this stuff.

From the two manuals, I have determined that the 10 blink code means:

Technical Guide:
Abnormalities of the F+15V.
 Reasons:
 The P board is not generating the F+15V
 SUB Voltages are affected by the K board or by
metal object present in the SD card slot..
Shorted Vsus (By the SS board or SC board).
Shorted Vda (By the panel, or any of the C board)
Wrong diagnostic by the A board.

Service Manual:
Sub 5V SOS
Sub 3.3V SOS
Sub 9V SOS
Tuner Power SOS
MIHO SOS
LED SOS

I've run through the power up sequence outlined in the Technical Guide. When Plugged in, the F+15v goes to 14.8v for roughly 10-15 seconds and then clicks off (normal unless the 14.8 volts is really supposed to be 15+vdc).

Once the plug-in routine us complete, when turned on, the F+15v clicks on for roughly 3 seconds then the relay clicks off again and the set issues the 10 blink code.

I have run the sub voltages on the A board through a series of tests during the 3 second power on period and have found the following:
Sub 5v = 5.0 vdc. Seems good to me
Sub 3.3v = 3.34 vdc. Seems good to me
Sub 9v = 8.94 vdc. Seems good to me

The Tuner Power appears to come off of one of the Sub 5v, so I assume this is OK (may have to test that at the tuner?)

The MIHO appears to come from the Sub 3.3v, so I haven't tested that yet. I may have to investigate this circuit a little deeper.

The LED 8v I have not tested simply because the LED seems to be the one thing that's working.

I'm going to continue to test through the rest of the Sub voltages as I have finally gotten pretty good at finding these test points. I'll update these results.

After that, I'll test the P+15v that is supposed to come from the P board after the "Main Panel On 3.2v" signal comes from the D board. I haven't determined if the "Main Panel On 3.2v" is being issued or if this part of the sequence is already interrupted prior to that signal being issued.

I have confirmed that Vsus and Vda do not come up during the power on sequence.

Any help you experienced guys can offer would be much appreciated. If I can skip some steps and get straight to the problem, it will be a life saver. I'd prefer to fix this expensive TV.

Thanks so much,
Dan

[tw2005]

Re: TC-P50VT20 10 Blink Code

Are you looking at the Technical Guide
2010 Panasonic 3D Plasma TV (13th Generation)?

You could check the SC board out and see if any of the heatsinked transistors are shorted.

Q661 RJP63F3A would be one but check these too 45G128,30f125,DG502, DG402 for short cct.

If nothing is bad on the SC, then in that guide it talks about isolating the A-board and the TV self turns on with white screen, could try that. If it powered up with the sustain boards running then that could suggest the A-board is at fault.

Check SD card slot for damaged pins or metallic foreign object shorting that out, have read of kids sticking coins in there.

In that guide it gives a number of Behavior After Connectors Removal tables to confirm what the TV should do with things disconnected, that may help.

[Katzat]

Re: TC-P50VT20 10 Blink Code

Yes, that's the manual I have.

I'll look into those things and report back.

Thanks so much.

[Katzat]

Re: TC-P50VT20 10 Blink Code

Are you looking at the Technical Guide
2010 Panasonic 3D Plasma TV (13th Generation)?

You could check the SC board out and see if any of the heatsinked transistors are shorted.

Q661 RJP63F3A would be one but check these too 45G128,30f125,DG502, DG402 for short cct.

If nothing is bad on the SC, then in that guide it talks about isolating the A-board and the TV self turns on with white screen, could try that. If it powered up with the sustain boards running then that could suggest the A-board is at fault.

Check SD card slot for damaged pins or metallic foreign object shorting that out, have read of kids sticking coins in there.

In that guide it gives a number of Behavior After Connectors Removal tables to confirm what the TV should do with things disconnected, that may help.

TW, I found the Q661 transistor on the board and in the service manual labeled on the printed circuit board drawing, but I couldn't find it in the schematic. What I could find on the schematics was Q16661. It appears that all of the components on this board are prefaced with the "16".

Am I reading this correctly?

I was looking at the schematic to determine if I had to take the transistor out of the circuit to test it. It appears that I do. Is this correct, or is there anyway to test these without removing them from the board?

[tw2005]

Re: TC-P50VT20 10 Blink Code

Yes you're reading it right and no you don't need to remove it.just see if anything is shorted which is simple as measuring across the legs and see if dead short or very low ohms

[Katzat]

Re: TC-P50VT20 10 Blink Code

Yes you're reading it right and no you don't need to remove it.just see if anything is shorted which is simple as measuring across the legs and see if dead short or very low ohms

OK. I ran some more tests.

Q661 has 32 Ohms between the Emitter and the Collector, 32 Ohms between the Emitter and the Base, and is shorted from the Base to the Collector. I was using the multimeter in auto ranging resistance mode, not diode mode.

I then ran the Method to Turn On the Panel Drive Circuit Only (A Board Isolated) on page 63 of the Technical Guide (A Board disconnected from the D Board) and the TV did not turn on by itself when plugged in. The relays clicked on plug in, but quickly clicked off in about a second, not the 15 seconds that they stay in with the D board connected.

I then ran the next test on that page (Completely Isolated A Board) and nothing happened when the TV was plugged in. Nothing at all. The manual says the LEDs on the SS and SC boards should turn on, but I don't see any LEDs on those boards. Nevertheless, there was no clicking of any relays, etc.

I ran the last test on that page to get the White Screen, and nothing happened at all. I guess this is expected as nothing happened on any of the previous two tests.

From this, am I to assume the problem is in the D Board 3.2v PANEL MAIN ON signal? Should my attention go to this board? This is confusing as it appears the A Board is necessary to command power to the D Board CPU which issues the 3.2v PANEL MAIN ON signal back to the P Board.

What am I missing here? What's next?

[tw2005]

Re: TC-P50VT20 10 Blink Code

OK. I ran some more tests.

Q661 has 32 Ohms between the Emitter and the Collector, 32 Ohms between the Emitter and the Base, and is shorted from the Base to the Collector. I was using the multimeter in auto ranging resistance mode, not diode mode.

I then ran the Method to Turn On the Panel Drive Circuit Only (A Board Isolated) on page 63 of the Technical Guide (A Board disconnected from the D Board) and the TV did not turn on by itself when plugged in. The relays clicked on plug in, but quickly clicked off in about a second, not the 15 seconds that they stay in with the D board connected.

I then ran the next test on that page (Completely Isolated A Board) and nothing happened when the TV was plugged in. Nothing at all. The manual says the LEDs on the SS and SC boards should turn on, but I don't see any LEDs on those boards. Nevertheless, there was no clicking of any relays, etc.

I ran the last test on that page to get the White Screen, and nothing happened at all. I guess this is expected as nothing happened on any of the previous two tests.

From this, am I to assume the problem is in the D Board 3.2v PANEL MAIN ON signal? Should my attention go to this board? This is confusing as it appears the A Board is necessary to command power to the D Board CPU which issues the 3.2v PANEL MAIN ON signal back to the P Board.

What am I missing here? What's next?

I would have stopped once i found q661 shorted.

[tw2005]

Re: TC-P50VT20 10 Blink Code

So on the SC, if Q661 is shorted, of those other transistors I mentioned any of those shorted? There should be.

Across the pins at SC2 what's the resistance there?

If you're happy Q661 is short then it's SC board failure, next step is to resistance test the SD/SU boards. The G20,G25 training guide has some info you could use.

If they're ok, and assuming SC confirmed bad then send it off for a rebuild PTS electronics inc.

[Katzat]

Re: TC-P50VT20 10 Blink Code

I would have stopped once i found q661 shorted.

Ha. I was wondering about that.

[tw2005]

Re: TC-P50VT20 10 Blink Code

Ha. I was wondering about that.

yeah and it mentioned a link or jumper had to be in place on the P-board for that test to work isolating the A-board which it may have already, I don't know , never worked or tried this myself as I've never had the pleasure of doing the 3D model.

But I know it works because others have tried it but if the SC is shorted then it's not going to work.

You just have to be sure yourself it's bad. Bad SC generally in the G20,25 models triggers 10 or 4 blink. Just depends how much it shorts. dead short across SC2 will cause the 4 blink since it's shorting 200V on the P board.

And I've read of people starting with 10 blink and have it change to 4 after trying to turn it on several times.

I'd expect the VT series SC would fail similar to the other models even though the cct is somewhat different.

10 blink is one of those codes virtually any board could cause to trigger.

[Katzat]

Re: TC-P50VT20 10 Blink Code

So on the SC, if Q661 is shorted, of those other transistors I mentioned any of those shorted? There should be.

Across the pins at SC2 what's the resistance there?

If you're happy Q661 is short then it's SC board failure, next step is to resistance test the SD/SU boards. The G20,G25 training guide has some info you could use.

If they're ok, and assuming SC confirmed bad then send it off for a rebuild PTS electronics inc.

Sir, I really appreciate this. I'll dig back into this tonight. I'll have to find those other transistors to test them. When I cursorily searched the manual for them I couldn't find any.

Will the SC Board repair be more than I can handle by myself?

Also, can this failure on the SC Board cause the other A Board isolation test failures I mentioned?

[tw2005]

Re: TC-P50VT20 10 Blink Code

Sir, I really appreciate this. I'll dig back into this tonight. I'll have to find those other transistors to test them. When I cursorily searched the manual for them I couldn't find any.

Will the SC Board repair be more than I can handle by myself?

Also, can this failure on the SC Board cause the other A Board isolation test failures I mentioned?

You won't in the manual but your eyes will when you look at the markings on them on the board.

majority of those part numbers in the manual are useless as they're a Panasonic reference to a part supplied by another company.The only time the part number is real is when it's a Panasonic component which some are but not many.

You're looking at components from RENESAS, TOSHIBA, ROHM, MITSUBISHI, ON-SEMI, SANYO , NEC just to name a few brands.

Maybe not beyond your ability but safest bet is to send it somewhere. There's bound to be some small SMD components that will need replacing though.

Never done the AK or AY revison boards. May get lucky with a kit.

You could through the TNPA5081 thread to get some idea but that is for the 2D model versions. A lot of the same parts but some are in different locations because schematically there are differences.

[tw2005]

Re: TC-P50VT20 10 Blink Code

The A-board isolation is handy if you want to prove everything else works and it's the A-board but for that to work everything else need to be good.

When the SC fails there's virtually always shorted transistors.

[bc989]

Re: TC-P50VT20 10 Blink Code

....

10 blink is one of those codes virtually any board could cause to trigger.

Can't agree more to that. 10 blink on my PX80 led me all over the place until the culprit was found on the C3 board - a bad capacitor on 75V.

[Katzat]

Re: TC-P50VT20 10 Blink Code

So on the SC, if Q661 is shorted, of those other transistors I mentioned any of those shorted? There should be.

Across the pins at SC2 what's the resistance there?

If you're happy Q661 is short then it's SC board failure, next step is to resistance test the SD/SU boards. The G20,G25 training guide has some info you could use.

If they're ok, and assuming SC confirmed bad then send it off for a rebuild PTS electronics inc.

OK, I checked all the transistors you listed that I could find. These are listed with their schematic component names so I can find them in if I need to see what resistance should be expected around them:

Q452 (45G128): C-G =1.3 Ohms, C-E=.3 Ohms, G-E=1.2 Ohms
Q441 (45G128): C-G =2.4 MOhms in the Positive Direction and 4.6 kOhms in the negative direction, C-E=2.3 MOhms in the positive direction and 1.6 MOhms in the negative, G-E=46 kOhms in both directions.
Q661 (30F125): C-G =45 kOhms, C-E=60 kOhms in the positive direction and 4.5 kOhms in the negative, G-E=47 kOhms.
Q662 (30F125): C-G =45 kOhms, C-E=60 kOhms in the positive direction and 4.5 kOhms in the negative, G-E=47 kOhms.
Q402 (DG502): C-G =.1 Ohms, C-E=.1 Ohms, G-E=.3 Ohms.
Q403 (DG502): C-G =6.7 Ohms, C-E=.1 Ohms, G-E=6.7 Ohms.
Q421 (DG402): C-G =5.5 Ohms, C-E=.1 Ohms, G-E=8,1 Ohms.
Q422 (DG402): C-G =8.1 Ohms, C-E=.1 Ohms, G-E=5.5 Ohms.

It appears that some of these are shorted in some of the directions.

While I was inspecting the board for these tiny part numbers, I noticed some corrosion or something on many of the solder joints and exposed solder test points that looked like the stuff that builds up on batteries when they're left in a device for too long. It's only noticeable with the light and magnifying glass, but it seems to be everywhere.

What is this and what causes it?

Hopefully this photo attaches and the white stuff is visible.

[tw2005]

Re: TC-P50VT20 10 Blink Code

Could be flux or the conformal coating.good news is you're finding commonly failed parts shorted so I think you can safely say the sc is the 10 blinker.

Test the buffers resistance as per that guide and get the tnpa5081 rebuilt

[Katzat]

Re: TC-P50VT20 10 Blink Code

Could be flux or the conformal coating.good news is you're finding commonly failed parts shorted so I think you can safely say the sc is the 10 blinker.

Test the buffers resistance as per that guide and get the tnpa5081 rebuilt

Thanks TW. I'll wrap this up and get it sent out.

[Katzat]

Re: TC-P50VT20 10 Blink Code

Could be flux or the conformal coating.good news is you're finding commonly failed parts shorted so I think you can safely say the sc is the 10 blinker.

Test the buffers resistance as per that guide and get the tnpa5081 rebuilt

TW, I hate to bother you again, but I was reading through the Troubleshooting handbook you gave me trying to find the word Buffer (to test the buffer resistance) and I couldn't find it. Is there another word for buffer or a specific page for that procedure.

Also, as I was pouring through that manual, I found it was WAY more useful than the similar manual I have for my specific TV. It actually has a 10 Blink Code troubleshooting procedure. So, just for fun, I decided to run through it just to prove what I think I already know (that the SC Board is bad).

But when I run the procedure on page 53, I get to the point where I disconnect SC20 and power the unit on, and I still get the 10 blink code. according to the procedure, it would appear that my problem is in the A Board based on that. If the SC Board is the culprit, the procedure says the LED should blink 6 times with SC20 Disconnected.

Is this an error in the procedure or is the VT20 different than the G series TVs?

[Katzat]

Re: TC-P50VT20 10 Blink Code

I figured out that the SU and SD boards are the buffer boards. The test points on my board were different than those shown in the Troubleshooting handbook, but I was able to do the tests from the pinouts and got roughly the readings specified.

The 5V_F reading on the SD board was roughly 10 MOhm Rather than the 5.7, but it was definitely not shorted.

As soon as I hear from you regarding the troubleshooting anomaly above, I'll wrap this up and send this for rebuild.

[vinceroger69]

Re: TC-P50VT20 10 Blink Code

this is tom66 video on how to test buffer boards
https://www.youtube.com/watch?v=51SZsfH60EY