Panasonic TC-P55GT30 NO POWER/NO LED

[lectrplatr]

Need some coaching on this.

The TV goes dead, out of the blue. Small pop, quick screen flash, a little smoke.

I removed the back, found an arch burn on the P board, bought a replacement, installed.........nothing. Fuses on P and sub check ok. Pretty sure I have live boards, but can't say at what level.

I've tried using a troubleshooting guide to point out a board, but not quite sure?
No relay clicks on the sub board. Could this be my problem, since, the arch was on the P?

Any ideas, directions?

[sordids999]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Posting pictures of the back of your tv showing the boards with clear pictures may help you more with fixing your problem

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

You need to figure out if the new PS has 5V going to the mainboard. Mainboard turns on the rest of the powersupply.

Measure for 5V on the big white connector on the right side of the powerboard. Its the connector that goes to the MB.

1) You either missed a connector on the mainboard , try reseating thm.
2) Bad replacement board.
3) Bad mainboard.

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

These are the boards in the TV.

If the tv is still dead after replacing the main powersupply then your mainboard is dead.

[lectrplatr]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

This is the board that I replaced I've been able to check that the boards are not grounded.
There is power to the sub power board, but nothing through to the P board main connector.

Could this be a problem with the relays on the sub board, or maybe no power from the A board. I'm learning as I go.

Thanks!

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

What is that with that jumper wire and how do you measure the voltages?

Black prope to ground/chassis and red prope on the big white connector on the right side of the powerboard.

How much voltage do you measure on the P34 connector? Its the connector on the bottom side of the board.
You dont measure any 5V on the white connector? I will check my own 55VT30 when i get home.

[lectrplatr]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Moreno83,

I checked, as you said. There is no voltage on the P55 connector. There is no voltage through the P34 loop connector.

Thanks for explaining, I'm really quite the novice. I've been trying to research how this all works. Is there an "on" signal that has to come from the other boards somewhere, before the relays can power on the sub board and then send to the main?

Thanks and have a great day there!

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Do you have any voltages going into the powerboard on the left side? So from the sub pboard to the powerboard when you plug in the mains.

I will open up my 55VT30 tonight , will be at 18:30 europe time and measure the normal standby voltages when the mains are plugged in. The boards are the same.

[lectrplatr]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Sorry about that. I must have measured the wrong side of the connector. I was measuring at the arrow point, but that must be the neutral side. Like I say I'm new at this.

I am able to measure only about 2.4 volts on both the P sub and P main through the P55-P56 connector. There is 118 volts on the main line inlet. The voltage on the P51-P52 connector is pretty low at about 0.25 volts.

Is this a bad P sub board? I haven't tried the P57-P58 connector. Not really sure on that one.

Thanks for taking the time

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Hmm , i think you are measuring the wrong way or both boards are dead.

Can you take a picture of how you are measuring the voltages? Meter must be set to Volts DC and the black prope must be on the chassis/ground. Red prope is going to the connectors etc.

220V ( 120v usa? ) is going into the P sub and then into the P board. You should normally have 5V on pin 6 of the white connector if the power boards are ok. 5V STB is going to the mainboard who then tells the power supply to turn on ( 5VSTB_ON ) which then turns on the F15V rail.

Don't forget that every power supply in every tv has a PRIMARY and SECONDARY side. ( HOT and COLD ). Primary = AC on the meter and Secondary is DC on the meter.
So in europe the 220V goes into the power supply and you will see a black line in the middle of the power supply cutting the PS in half. There are "optocouplers" close to that black line and transformers. The voltage in the SECONDARY side will be around 3.3 , 5V and 15V and the primary side will be HIGH voltages so watch out.

Can you please measure the voltages on both boards and take some pictures?

Can you measure the voltages on the optocouplers? One side will be AC voltage and other side will be DC. ( High voltage to low voltage ).

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Here is the service manual , search for "STB"

[lectrplatr]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Sorry for the delay, been "making merry."

I'm not sure on measuring the optocouplers. I see several black lines dividing the boards, and think I can roughly see the AC to DC conversion.

I measured both DC and AC on the main power inlet (sub) and main inlet to the power inlet(P)

It confuses me why if I measure the (P) inlet as DC, I get a (-) negative value, but AC checks around 2 volts. It also, seemed that the (P) voltage decreased from time to time? The main line voltage remains the same.

Still no relays click, no LED or blinking of any kind.

?

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Ok remove ALL cables from the P sub board that are going to the PS and only keep the power cable attached. I did the same but i sold the tv...i only got the P sub board haha.

Measure the outer pins on P55 in AC VOLTAGE ( Pin 1 and 3 ) --> Must be 120V for USA.
Measure the outer pins on P51 in DC VOLTAGE --> Probably starts at +/-50/60v and counts down because its not connected to the PS.

Ps , use a screw on the board as ground. Let me know what you measure.

[lectrplatr]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Whoopie!

I just replaced the sub power supply board. Relays clicked, no "fireworks." Turned it on and displays input name and then "no input" signal message.

Is there anything I need to adjust or pay special attention to before I close up and input an hdmi?

Both power supply board were replaced.

Thanks for helping

[tvtimmy]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

Check that all the screws holding in the boards are tight, better yet, replace them with the new ones with lock washers. If not, next thing to go will be SC and SU boards.
I fixed my SC but I cant do a SU repair. I will have to send it out to be fixed.

[Moreno83]

Re: Panasonic TC-P55GT30 NO POWER/NO LED

SU/SD boards are very expensive for this model...

Glad you fixed it! As TvTimmy says , use NEW screws on the SC board and tighten them , they are loose now.