Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

[amanitadragon]

Hey, Everyone. I'm a total newbie to electronics repair, but I do own a decent digital multimeter. I need some help getting a Panasonic TC-P50G25 back up and running. I've detailed my troubleshooting process below and I'm hoping to any general advice as you all may have, and get some answers to the specific questions at the end of the post. Thanks in advance! Sorry if the level of detail is excessive.

Problem: In-laws were using the TV one night. Father in-law turned it off, mother in-law wanted to keep watching and tried to turn it on, but it would not turn on. Apparently, there was initially a 4-blink code, but later (after some unplugging and plugging back in to different outlets, etc.) a 10-blink code.

Troubleshooting: TV was left unplugged for >12 hours and power button held down in order to discharge/reset. This did nothing. Still 10 blink code when powered on.

That's where I came in. After googling around a bit I popped off the back cover, dusted the boards with compressed air, and visually inspected all of the capacitors for bulging/leaking. I found no defects.

I read through various threads on this site and found the “2010 – FHD Plasma TV Troubleshooting Handbook,” which is a fairly comprehensive handbook released by Panasonic for technicians working on G20 and G25 series TVs (PDF is attached to this post).

Below are the results of working through the troubleshooting guide.

PDF Slide 8 – Quick procedure to check for short or low resistance condition of the Vsus, Vda, and P15V lines

The TV has been disconnected for several days, so I skipped the step where residual charge is removed by grounding through a 500 ohms resistor. I measured the resistances indicated in step three of slide 8 (black lead on chassis and red lead on the indicated pin on the P-board) and obtained the following:

P11/White (Pin1, Vsus) --> 429 Ohm
P11/Brown (Pin 4, P15V) --> 29.2 Ohm.
P35/White (Pin 1, Vda) --> Starts out at around 15 MOhm and drifts downward (reached 5 MOhm after a minute or two and continued to decrease)

Based on the above readings, it appears that there is both a P15V and a Vsus short, or partial short.

Slide 12 – Detailed troubleshooting procedure for shorted Vsus.

Step 1: Unplug connectors P2 and P11 on P-board and measure resistance between P2 (pin 1) and ground (Chassis).
Result: 15 MOhm and dropping. No short.
Step 2: Measure the resistance between pin1 of connector SC2 on the SC board and ground (Chassis).
Result: 432 Ohm. Short.
Step 3: Measure the resistance between connector SS11 (pin1) on the SS board and ground (Chassis).
Result: 4 MOhm. No Short.
Final Result: Replace SC Board.

Slide 13 – Detailed troubleshooting procedure for shorted P15V

Step 1: Unplug connectors P6 and P11 on the P-board and measure resistance between P6 (pin1) and ground (Chassis).
Result: 7.77 kOhm. No short.
Step 2: Reconnect P11 and measure the resistance between P6 (pin1) and ground (Chassis).
Result: 2.64 kOhm. No short.
Step 3: Disconnect SC20 on the SC board and reconnect P6. Measure the resistance between P6 (pin1) and ground (Chassis).
Result: 7.8 kOhm. No short.
Final Result: Replace SC board.

Ok, so it looks like the SC board is bad. But….just to be sure, I followed the advice of TW2005 on this thread and checked the following IGBTs:

Q402 --> G-E = 6.3 Ohms; E-C = Short; G-C = 7 Ohms
Q403 --> G-E = Short; E-C = Short; G-C = Short
Q421 --> G-E = 5 Ohms; E-C = Short; G-C = 5 Ohms
Q422 --> G-E = 7.2 Ohms; E-C = Short; G-C = 7.2 Ohms
Q661 --> G-E = 9.5 Ohms; E-C = Short; G-C = 9.5 Ohms
Q441 --> G-E = 47 kOhms; E-C = 367 kOhm; G-C = 47 kOhms

Now, I know that I need to replace the SC board, but I read in this thread that it is important to also test the SD and SU buffer boards before fitting a new, or refurbished, SC board. Once again turning to the Panasonic Troubleshooting guide (attached), I went through the following steps.

Slide 43 – Vfo, VSCN-F, & 5V_F Resistance Measurements (SU-SD boards)

Step 1: Remove the 4 VFG screws from the SU and SD boards…check!

Step 2: Disconnect SC41, SC42, and SC46 from the SC board. Also, remove the ribbon cable between the SU and SD boards (SU11/SD11).

Step 3: Using the VF-Ground as reference, measure the Vfo, VSCN-F, and 5v-F resistances on the SU and SD boards individually (here I used the Chassis as ground since the point highlighted in the image on Slide 44 of the troubleshooting guide does not appear to be a ground).

SU41 (pin2, TPSU15, 2.2M) --> 5.77MOhm
SU41 (pin4, TPSU16, 221K) --> 221KOhm
SU41 (pin8, TPSU17, 5.7M) --> No Response

SD42 (pin1, TPSD29, 2.2M) --> 6.14 MOhm
SD42 (pin2, TPSD28, 221K) --> 221K
SD42 (pin6, TPSD26, 5.7M) --> 15 MOhm (Rising, climbs over 20 MOhm)

I'm confused by a couple of things here.

First, it appears as though the troubleshooting guide has reversed the expected resistances for VFO and 5V_F. Would you all agree?

Second, when I test TPSU17 (both on the test point and on the actual pin) I get NO RESPONSE from the multimeter…nothing. In other cases (for instance when I indicated short above for various IGBTs) the voltmeter will go from reading “0.L” when not in contact with anything, to reading 000.1 Ohm when the two leads are touched together, or when reading an actual short. Why does this pin not respond at all? Also, why is the reading for the same line on the other board so high?

I repeated the above measurements after jumping pin1 and pin2 of SC50 with an alligator clip. Readings were identical to those without the jump.

Have I approached this problem correctly?

Do these overall results indicate that all three boards (SC, SD, and SU) are bad?

If so, what is the best way to fix/replace these boards?

Board , Part#
SC, TNPA5081AF (TXNSC1LPUU)
SD, TNPA5091
SU, TNPA5090

I've seen panel board repair at moduslinks for $220.20

I also see a trade in on eBay for just the SC-board for $137 plus $16 shipping. They (oleg_yj) say that if you send in the buffer boards, they will test them for free, but will charge for repair or replacement and do not list the price of the buffer boards.

[tw2005]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Give me half a day to read all this

[amanitadragon]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Haha.. Take your time and thanks! I figured it would save some back and forth.

[nomoresonys]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Give me half a day to read all this

[tw2005]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

........................................................
SU41 (pin2, TPSU15, 2.2M) --> 5.77MOhm
SU41 (pin4, TPSU16, 221K) --> 221KOhm
SU41 (pin8, TPSU17, 5.7M) --> No Response

SD42 (pin1, TPSD29, 2.2M) --> 6.14 MOhm
SD42 (pin2, TPSD28, 221K) --> 221K
SD42 (pin6, TPSD26, 5.7M) --> 15 MOhm (Rising, climbs over 20 MOhm)

I'm confused by a couple of things here.

Have I approached this problem correctly?

Do these overall results indicate that all three boards (SC, SD, and SU) are bad?

If so, what is the best way to fix/replace these boards?

Board , Part#
SC, TNPA5081AF (TXNSC1LPUU)
SD, TNPA5091
SU, TNPA5090



I also see a trade in on eBay for just the SC-board for $137 plus $16 shipping. They (oleg_yj) say that if you send in the buffer boards, they will test them for free, but will charge for repair or replacement and do not list the price of the buffer boards.

have you found my TNPA5081 repair chronicle (LOL) TNPA5081

I would say the buffers are fine. They usually are, however I had a TV with a bad set and popped a new SC.

If they were bad , at least one of those 3 check points would be dead short. usually Vfo.

Try reversing the probes, and yes they may have mixed up the results, I'll check but in my thread I did up a table of real results from my boards. thatwas before I found that G20/25 guide and they match up pretty good.

moduslink may be the cheapest and most reliable for the SC repair. You can also use rev AP & AW in sub for the AF.

If you're really keen and have heaps of time, then you could get the parts from china and get away with it for very little. there are some kits but not very cheap. If going for a kit I think i'd just get Modus to repair.

[tw2005]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Ok, so it looks like the SC board is bad. But….just to be sure, I followed the advice of TW2005 on this thread and checked the following IGBTs:

Q402 --> G-E = 6.3 Ohms; E-C = Short; G-C = 7 Ohms
Q403 --> G-E = Short; E-C = Short; G-C = Short
Q421 --> G-E = 5 Ohms; E-C = Short; G-C = 5 Ohms
Q422 --> G-E = 7.2 Ohms; E-C = Short; G-C = 7.2 Ohms
Q661 --> G-E = 9.5 Ohms; E-C = Short; G-C = 9.5 Ohms
Q441 --> G-E = 47 kOhms; E-C = 367 kOhm; G-C = 47 kOhms

ok, I've got this wrong, Q452 in lieu of Q441

basically for the IGBTs, usualy looking at RJP63F3A, DG402, DG502, 30F125, 45G128

But there's more to it then just those.

[amanitadragon]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Ok, I reversed the probes and got a reading for 5V_F on the SU board (8.1M).

I've begun to look at your 'chronicle' its a doozy...a LOT of work there. I've attached a spreadsheet with the rest of my readings from the buffer boards, next to yours from that thread. Is there any reason why I might have elevated readings for Vfo? Notice that with probes reversed I did not get OL for pin7 on the SD board??

Q452 --> G-E = Short; E-C = Short; G-C = Short

I like to learn, but don't have the heaps of time needed for component repair of this board.. I suppose I will try modus if we can be fairly certain that the Buffers are good..

Thanks alot for your help!

[tw2005]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Some data i collected from 3 sets.

SU

pin
2. vfo. 1.3ohm , 1.5ohm, 1.87m

4. vsc-f. 217k , 220k, 220k

8. 5v_f. 2.3m , 1.2ohm, 6.3m

SD
1 VFO. 1.1OHM , 1.7M , 1.83M

2 VSCN-F. 218.8K, 220K ,219K

6 5V_F. 500-600K , 4.36M, 5.1M


Bold is ok

[amanitadragon]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Do my higher readings for Vfo indicate a potential problem with the buffer boards? (see previous post)

[tw2005]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Do my higher readings for Vfo indicate a potential problem with the buffer boards? (see previous post)

No, I think somewhere in the bowels of that thread of mine johnboy1313 had a similar issue not being able to attain the results.

Could simply be the meter. what do you have?

I would push on and just get the Sc board done. What you have there will not blow the board and I expect this will work once the SC is done.

With the polarities swapped

SU41
1 OL
2 6.8 Mohm
3 OL
4 219.8 kohm
5 OL
6 OL
7 OL
8 Starts low and quickly ramps up to OL
9 OL

SD42
1 6.7 Mohm
2 217.5 kohm
3 OL
4 OL
5 Starts low and quickly ramps up to OL
6 >30 Mohm
7 OL
8 >30 Mohm
9 OL

I probed all SU41 and SD42 again with red on the ground pan with the same results that I saw yesterday.

[amanitadragon]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Meter is an Ideal Test Pro 61-340.

I ran back over every pin with Black on Ground and Red on Ground. My results are nearly identical to Johnboy1313 except for SU41 (pin8) where I get 8.07M with Red on ground and he gets 1.87M with Red on ground.

Looks like I'll go ahead and seek out an AF or AP board, or send mine in to be repaired...

Thanks for all of your help.

[amanitadragon]

Re: Panasonic TC-P50G25 Plasma 10 blinks at power on. Bad SC, SD, and SU?

Just an update. I sent the SC board to ModusLink PTS (free shipping both ways if you ask for a shipping label and live within the US). There was a sale (still is until January 25, 2015), so I got the repair and return for $80 shipped.

Popped it in and it worked!

Thanks again everyone.