Panasonic G20 Failure :/

[Falco21]

New member here. Been on forums for a long time.

I currently have a 50" Panasonic G20 Plasma. TC-P50G20

It is about 2 years old and has worked flawlessly. The other night I was watching TV and when I shut it off, I heard a pop noise. Tried to turn it back on and now all it does is attempt to turn on, then turn itself off. The red LED light blinks 10 times. I replaced the Power Board and the Video Board, still with the same issue. The only board I have not touched is the Y Board. Does anyone know what could be causing this?

[tom66]

Re: Panasonic G20 Failure :/

Service manual: (wait 30 seconds until "Get Manual" appears below image preview.)

Diagnosis procedure for 10 blinks (page 17) indicates the following boards possibly at fault:

A-Board (you've probably replaced this, it's the board with the inputs)
SC-Board (Y board)
SS-Board (Z/X board)
P-Board (replaced)

Faults are: Sub 5V SOS, Sub 3.3V SOS, Sub 9V SOS, Tuner Power SOS.

Do you have a multimeter?

The pop noise to me suggests SC or SS boards.

[Falco21]

Re: Panasonic G20 Failure :/

Service manual: (wait 30 seconds until "Get Manual" appears below image preview.)

Diagnosis procedure for 10 blinks (page 17) indicates the following boards possibly at fault:

A-Board (you've probably replaced this, it's the board with the inputs)
SC-Board (Y board)
SS-Board (Z/X board)
P-Board (replaced)

Faults are: Sub 5V SOS, Sub 3.3V SOS, Sub 9V SOS, Tuner Power SOS.

Do you have a multimeter?

The pop noise to me suggests SC or SS boards.

I just ordered the SC Board this morning.

And yes, I do have a multi-meter. What do you need me to check?

Thank you for your help!!

[tom66]

Re: Panasonic G20 Failure :/

The SC, which is also labeled as the Y Board, and the SS-Board are the same correct? I just purchased the SS board and it also says it is the Y Board.

No, they are different boards. The SC board is the SCan board, and it controls the buffers to produce the picture on the screen. With a malfunctioning SC board you will get -no picture- if there is no short.

The SS board does not scan the screen. It is the Second Sustain (that's how I like to remember it, it probably stands for something entirely different.) With a malfunctioning SS board you will get a picture but it will be very poor (dim, slow, blurry, sometimes purple-tinted.)

However the most common failure on both is a short circuit, so the only way to identify the failed board is by unplugging them individually.

On all Panasonic plasmas that I know, from the back of the TV, the SC is on your left and the SS on your right.

And yes, I do have a multi-meter. What do you need me to check?

Can you take some clear photos of inside of your TV? I'll highlight test points and checks to do.

Any TV saved from landfill is a victory in my opinion. There is far too much waste in this world.

[Falco21]

Re: Panasonic G20 Failure :/

Here is one of the entire back:



Main Power Board (That I replaced):



A-Board (That I replaced):



SC Board:

[tom66]

Re: Panasonic G20 Failure :/

Okay, conventional layout there. In your picture, left is SC, right is SS.

Try unplugging the SS board (both the main power connector and the little control connector, but not the panel ribbons) and turning the TV on. Does the blink code change? Or does the light go green?

If not, unplug the TV again, wait 30 seconds, then plug in the SS board, then unplug the SC board (again, all the power and control connectors - but don't unplug the buffer boards going to the panel or any of the panel ribbons.) Power it up again and see if the code changes, or if the light goes green.

[Falco21]

Re: Panasonic G20 Failure :/

Unplugged the SS Board and the light now blinks 4 times.

Plugged the SS Board back in and tried the SC Board. When unplugging the SC Board, it blinks 7 times

[tom66]

Re: Panasonic G20 Failure :/

Unplugged the SS Board and the light now blinks 4 times.

Plugged the SS Board back in and tried the SC Board. When unplugging the SC Board, it blinks 7 times

With all control connectors disconnected...? Unexpected on my part...

Okay get out the meter now. Unplug mains power. Wait 30 seconds. Unplug the SS and SC power (don't worry about control.) Set meter to 200 ohms. Probe between the brown and white power connector wires. Your meter reading should remain unchanged from what it originally showed at 200 ohms for both boards if the boards are okay.

[Falco21]

Re: Panasonic G20 Failure :/

With all control connectors disconnected...? Unexpected on my part...

Okay get out the meter now. Unplug mains power. Wait 30 seconds. Unplug the SS and SC power (don't worry about control.) Set meter to 200 ohms. Probe between the brown and white power connector wires. Your meter reading should remain unchanged from what it originally showed at 200 ohms for both boards if the boards are okay.

I don't understand what you mean by "probe between the brown and white power connector wires".

Also, if it means anything, when I tried to connect the power wire to the SC Board, it sparked.

[tom66]

Re: Panasonic G20 Failure :/

I don't understand what you mean by "probe between the brown and white power connector wires".

Sorry... I'll be more clear. Make sure red probe is in Volts/Ohm jack and black in the COM jack. On the exposed pins on the SC/SS board, touch the red probe to either side, and the black probe to the other side.

Also, if it means anything, when I tried to connect the power wire to the SC Board, it sparked.

This is normal... the capacitors are empty on one board and you charged them up rapidly by connecting them to the P board. Plasma TVs use high voltages (typical "Vsus" is 205V for Panasonic) but 30 seconds are usually sufficient to dissipate these to a safe level. Also, from what I remember, there is a useful safety feature on Panasonic PDPs; a little LED will remain lit on the SC or SS board if there is still a significant stored charge.

[Falco21]

Re: Panasonic G20 Failure :/

I sometimes can get a reading, and sometimes it shows nothing. The SC Board showed a few times a reading of 104 then 105. The SS Board showed a few times 198 or so.

[tom66]

Re: Panasonic G20 Failure :/

I sometimes can get a reading, and sometimes it shows nothing. The SC Board showed a few times a reading of 104 then 105. The SS Board showed a few times 198 or so.

Is the reading very brief? That's okay as long as it doesn't stay.

[Falco21]

Re: Panasonic G20 Failure :/

Yes it is very brief. Flashes on and off. I tried holding on there, but the reading only shows a few times, not all the time.

[Falco21]

Re: Panasonic G20 Failure :/

New SC Board is on the way.

Seems like the problem

[tom66]

Re: Panasonic G20 Failure :/

New SC Board is on the way.

Seems like the problem

If not, it could be SS, SU or SD! I am disappointed that this Panasonic does not tell you which board is at fault. When I repaired a TC-42PZ70BA (old model, but very very well engineered) it would stop flashing the LED if the SC board was unplugged; I used this to quickly isolate that board as being at fault.

[Falco21]

Re: Panasonic G20 Failure :/

Well this sucks! LOL

Trial and error like I've been doing I guess :/

[waitery]

Re: Panasonic G20 Failure :/

Well this sucks! LOL

Trial and error like I've been doing I guess :/

Falco, did you get the new SC board and did it take care of the issue? Can you let us know? Thanks!!

[mr.sky]

Re: Panasonic G20 Failure :/

Okay, conventional layout there. In your picture, left is SC, right is SS.

Try unplugging the SS board (both the main power connector and the little control connector, but not the panel ribbons) and turning the TV on. Does the blink code change? Or does the light go green?

If not, unplug the TV again, wait 30 seconds, then plug in the SS board, then unplug the SC board (again, all the power and control connectors - but don't unplug the buffer boards going to the panel or any of the panel ribbons.) Power it up again and see if the code changes, or if the light goes green.

Tom, to your knowledge, do all the Panasonic Plamas have a Green Light
on the SS Board. I too, have the 10blinks, When i turn power on, my SC
board has a Green led that lights up, but not the SS board. Also my
A-Board has a Red light that comes up. Wonder if I have a Bad SS board.

[tom66]

Re: Panasonic G20 Failure :/

Tom, to your knowledge, do all the Panasonic Plamas have a Green Light
on the SS Board. I too, have the 10blinks, When i turn power on, my SC
board has a Green led that lights up, but not the SS board. Also my
A-Board has a Red light that comes up. Wonder if I have a Bad SS board.

I haven't worked on a recent G20 chassis, but on the TH-42PZ80BA both boards have LEDs lit up on them to indicate the presence of high voltage. (Very nice feature from Panasonic so you can't shock yourself.) Look for a place for an LED; is it lit?

[mr.sky]

Re: Panasonic G20 Failure :/

I haven't worked on a recent G20 chassis, but on the TH-42PZ80BA both boards have LEDs lit up on them to indicate the presence of high voltage. (Very nice feature from Panasonic so you can't shock yourself.) Look for a place for an LED; is it lit?

On Schematic, it shows Led location on SC board, but it does not
indicate on SS board. On my post concerning TC-42xp14, I have
included link to schematic. I even turned of the lights, and power up
tv, and still do not see any kind of led light coming on SS