TC-P42U2 panasonic 42" plasma, 10 blinks

[ga70gto]

Well guys, glad I found this forum, I think. Maybe i'd be better off if I'd resisted the challenge to try and fix this tv after what I've read here and other places on the net but here goes. i'm a car technician so I know "basic" electronics, of course we don't usually replace any components at the dealership level but you have to be able to read a wiring diagram but that still makes me a newbie.. Whoever draws tv wiring diagrams has to be in cahoots with the people that make eyeglasses. To cut to the chase this set has the 10 blink code so I'm hoping that maybe I'll be able to fix it since boards seem to be scarce but this tv is only 4 years old, 2010 model. I've been able to download both the repair manual and the 2010 technical guide and that's been a big help.

By following the guide (hope some of you have a copy) and disconnecting connector SC2 I was able to change the code from 10 blinks to 7 blinks. I disconnected the SM board from the SC board and reconnected the SC2 connector, the tv went back to 10 blinks. So, like many others I must have a bad SC board, right?

I performed the basic resistance checks per the guide with a result of 197k ohms for the first step (floating ground to TPSC1). (with SM connected)

Then I received 2.68k ohms (floating ground to pin 3 of IC724). (with SM connected)

The guide seems to assume that if these checks pass then you should proceed to checks on the SM board but since I have 10 blinks with the SM board totally disconnected my problem must be on the SC board (?).

My questions are: where should I go from here? and for those of you that have fixed these kinds of issues were the problems caused by defective parts? too much heat? (this tv has no fans, earlier models did) unknown? By searching the net I've notice that replacement boards are few and far between and even the "repair kits" are scarce.

I appreciate your patience and the sharing of your knowledge.

Pete

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

TNPA5105AD no doubt and yeah, rarer than rare! Occasionally one surfaces but never hangs around long and usually the 50". Board repair is best option

http://www.moduslinkptstvboards.com/txnsc1lhuu/

You could try a kit but it will involve SMD stuff that's tiny and also multipinned ICs.

So do you have the skills and equipment?

What was resistance across SC2 connector?

P5v and P15V resistance on the Sc, enters via SC20, check the schematic. The 15V feeds the FET driver and they generally fail and load up the 15V rail.

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

Actually a few for sale but mainly 50" and no bargains. Everyone knows how rare.

http://www.ebay.com/itm/Panasonic-TN...item35dd913931

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

I think someone has manages a self repair, I know my 5081 board is very close to this, so too 5066 (SN, HD model) in a way.

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

resistance across connector SC2, 1480 ohms

Resistance pin 6,7 (15v) to ground (chassis), 665 ohms

resistance pin 35 (5v) to ground (chassis) 1390 ohms.

thanks for responding "TW" I've read several of your posts with the troubles you've seen on these boards (TNPA5105 AD or similar).

Of course the board looks pristine, no smoke, burned traces, cold solder joints etc. Did any of yours actually show damage?

Thanks for the link to the board repair site that may be the way I go just hate it when something that looks perfectly fine doesn't work or work right. I'm thinking it would be a smart idea to send the SM board also to be checked and prevent damaging a repaired SC board.

Still, what would you suggest checking next? the transistors that are screwed to the heatsinks?

thanks for responding,

Pete

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

I have to wonder if all the bad things I hear about plasma are caused by the screen itself or the boards that support it since there's evidence of so many of them going bad.

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

resistance across connector SC2, 1480 ohms

Resistance pin 6,7 (15v) to ground (chassis), 665 ohms

resistance pin 35 (5v) to ground (chassis) 1390 ohms.

thanks for responding "TW" I've read several of your posts with the troubles you've seen on these boards (TNPA5105 AD or similar).

Of course the board looks pristine, no smoke, burned traces, cold solder joints etc. Did any of yours actually show damage?

Thanks for the link to the board repair site that may be the way I go just hate it when something that looks perfectly fine doesn't work or work right. I'm thinking it would be a smart idea to send the SM board also to be checked and prevent damaging a repaired SC board.

Still, what would you suggest checking next? the transistors that are screwed to the heatsinks?

thanks for responding,

Pete

Weird results, what type of meter and what range can it measure?
I'm fairly confident it's SC. You can try disconnectig Sc2, SS11, P35 and 3 white ribbons at the A board and powerup, it should turn on normally(no screen, no blinks) Don't reconnect anything straight away, let the voltage bleed off. At least 5 mins. Don't run it more than 30 secs

10 blinks is detected on the A board so if it passes then that clears both A and P boards leaving the others.

With those results i don't know the exact values but also depends on how accurate the meter is. SC 2 is definitely low, usually can be a few undre kilohms to megohms, The 15v line on my boards usually 1.25 -1.4k I would treat that as bad, the 5V could be ok, I get 5.6k but 1.39k could be normal not likely to trigger at that.

Of course I'm referencing to my 5081 boards and some others I've touched.

If I was to target transistors, try Q661, that's usually shorted and I think on this RJP43F4a or RJP56F4A would be targets.

You could test the SM yourself, just check for short between the earth pads where it bolts and the output pins of the buffers(the ribbon connectors for the Panel) just slide the tip slowly and observe or use a beep/ continuity.

0.7 in diode is normal, usually they will go dead short on individual pins.

[Alastair E]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

I have to wonder if all the bad things I hear about plasma are caused by the screen itself or the boards that support it since there's evidence of so many of them going bad.

Nah-- I would say that LCD/LED is more Unrepairable--due to the number of LCD Panel faults that occur....

Both Plasma and LCD are built to a price,--ie Costcutting leads to unreliability, add to the mix 'Planned Obsolescence' and the fact that it appears lots of technicians dont like/wont work on plasmas, or how to repair them to component-level gives the Plasma a bad name.

Lets face it--An LCD with stuffed caps in its PSU can be repaired by any man or his dog with an iron and a kit off fleagay, but a failed SC/Y-SUS takes a bit more time, knowledge and patience to repair.

I would much rather repair a Plasma than some boring Samsung LCD with dodgy caps in its PSU!

For the O/P-- I would check all the large IGBT's or MOSFETS on that SC and look for shorts or resistance leaks from S-D or E-C on each device. Often these parts are paired up,--wired in parallel so the short will appear on two such connected devices....

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

The meter I had used was a sears craftsman meter I use here at home to do "basic" car repairs. This evening I brought home my fluke meter from work, reassembled the board to make the same checks, some differences, not many. Where I list "normal" this is per the Panasonic guide.

floating ground to TPSC1, 195.9k ohms (190k or higher is normal)

floating ground to pin 3 of IC724 (IC16724), 2.656k ohms (2.6k is normal)

Per the guide, after the removal of the 4 floating ground screws and connectors SC41, SC42 and SC46 I took the following readings.

pin 1 of connector SC50 to TPSC1 only 1.84M ohms, Panasonic guide indicates it should be over 30M ohms. (if this was a car/truck I'd be asking myself, Ok, what's in between these two items that could be shorted?)

pin 1 of connector SC50 to pin 3 of IC724 (IC16724), 2.697k ohms (2.6k is normal)

SC2 pin 1 to pin 2, 3.021k ohms

SC20 pin 6,7 to chassis ground 685 ohms

SC20 pin 35 to chassis ground 5.57k ohms

I noticed some of these readings act very strange, when you first connect the leads the meter starts counting down, then it will start to count up again until it levels out. I've never seen anything like that on a car.

As always thanks again for your interest,

Pete

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

The meter I had used was a sears craftsman meter I use here at home to do "basic" car repairs. This evening I brought home my fluke meter from work, reassembled the board to make the same checks, some differences, not many. Where I list "normal" this is per the Panasonic guide.

floating ground to TPSC1, 195.9k ohms (190k or higher is normal)

floating ground to pin 3 of IC724 (IC16724), 2.656k ohms (2.6k is normal)

Per the guide, after the removal of the 4 floating ground screws and connectors SC41, SC42 and SC46 I took the following readings.

pin 1 of connector SC50 to TPSC1 only 1.84M ohms, Panasonic guide indicates it should be over 30M ohms. (if this was a car/truck I'd be asking myself, Ok, what's in between these two items that could be shorted?)

pin 1 of connector SC50 to pin 3 of IC724 (IC16724), 2.697k ohms (2.6k is normal)

SC2 pin 1 to pin 2, 3.021k ohms

SC20 pin 6,7 to chassis ground 685 ohms

SC20 pin 35 to chassis ground 5.57k ohms

I noticed some of these readings act very strange, when you first connect the leads the meter starts counting down, then it will start to count up again until it levels out. I've never seen anything like that on a car.

As always thanks again for your interest,

Pete

SC2 pin 1 to pin 2, 3.021k ohms BAD

SC20 pin 6,7 to chassis ground 685 ohms I'M CALLING THIS BAD

SC20 pin 35 to chassis ground 5.57k ohms THIS LOOKS MORE LIKE IT 5.6K

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

TW, concerning the checks of the SM board I had one strange reading. Using the diode/continuity setting of my meter I had no results on SM41 or SM46 however on pin 5 of SM42 the meter indicated .888 with no "beep". Switching over to the resistance setting on my meter indicated approximately 5M ohms. I only checked the 5 connections on the SC side of the SM board with the screws removed and these connectors disconnected.

Black lead where the screw would have been, probing with red lead.

So, is this one reading indicating a problem? strange that none of the other connections gave any results other than "OL".

Pete

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

TW, concerning the checks of the SM board I had one strange reading. Using the diode/continuity setting of my meter I had no results on SM41 or SM46 however on pin 5 of SM42 the meter indicated .888 with no "beep". Switching over to the resistance setting on my meter indicated approximately 5M ohms. I only checked the 5 connections on the SC side of the SM board with the screws removed and these connectors disconnected.

Black lead where the screw would have been, probing with red lead.

So, is this one reading indicating a problem? strange that none of the other connections gave any results other than "OL".

Pete

high resistance or OL would not be an issue, short or low ohms is. has this meter got a buzzer indicating shorts

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

No "buzzer" to indicate shorts, just the standard beep to indicate continuity. It's a Fluke 27 I've had for years and it's always been reliable.

Pete

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

slides 90-91


Procedure:
Remove the 4 VFG screws from the SM board. (See picture to the left.)
Remove SC41, SC42, and SC46 from the SC board. (See picture to the left.)
Resistance between VFG and VFO (TPSC1)
Using a digital meter, measure the resistance between VFG (Plated screw post) and VFO (pin 1 of connector SM42). (See picture in the next page.)
It may take a few seconds for the reading to become stable.
The normal resistance should be over 4 M-Ohms or higher (In lower range meters the resistance may read open).
Resistance between VFG and 5V_F
Measure the resistance between VFG (Plated screw post) and 5V_F (Pin 5 of connector SM42) (See picture on page 92)
The normal resistance should be 190K or higher.

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

No "buzzer" to indicate shorts, just the standard beep to indicate continuity. It's a Fluke 27 I've had for years and it's always been reliable.

Pete

That should do nicely, is it an old grey one? looks very similar to my 20 year old 73

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

What a coincidence I had just found those pages in the manual. Well, looks like if I decide to send out the SC board I should send the SM board with it, one is high and one is low.

VFG and VFO (pin 1), 1.572M ohms, manual indicates 4M or higher.

VFG and 5V_F (pin 5) 4.62M ohms, manual indicates 190k or "higher" (but this high?) is normal.

Pete

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

That should do nicely, is it an old grey one? looks very similar to my 20 year old 73

it's actually kind of an Army "green",

Pete

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

it's actually kind of an Army "green",

Pete

Mine's Army grey

[tw2005]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

What a coincidence I had just found those pages in the manual. Well, looks like if I decide to send out the SC board I should send the SM board with it, one is high and one is low.

VFG and VFO (pin 1), 1.572M ohms, manual indicates 4M or higher.

VFG and 5V_F (pin 5) 4.62M ohms, manual indicates 190k or "higher" (but this high?) is normal.

Pete

Guide is wrong. Reverse the probes on the VFo check and check value

5V_F should be what you have but,

Vscn_F pin2 should be the 190k

Not the first time I've seen stuff ups, they use incorrect terms and phot is of Sd/SU at the beginning. Someone probably tried the old cut and paste and it's slipped through, I'm thinking

[ga70gto]

Re: TC-P42U2 panasonic 42" plasma, 10 blinks

Leads reversed, 4.67M ohms

VFG to Pin2, 219.9K ohms

So, according to these measurements my SM board may just be okay.

Moduslink wants $110 to refurbish it, $50 to test it if nothings wrong, which I was considering just for the peace of mind.

So, unfortunately before you had responded with the "correct" diagnostic procedures I bought one off of Ebay for $28 including shipping. Seller had a 99.3% approval rating, so maybe I'll have a spare.

I never mentioned that the guy I got the tv from had "2" of them, I gave $50 for the tv not knowing if it could be fixed so at that time I wasn't willing to risk buying 2 dead TV's.

thanks for the continued support,

Pete