Panasonic 37” LCD LED

[Mmatt]

Picked up a Panasonic TC-L37D2 off the curb. When turned on it powers up and the backlights flash then it goes into shutdown mode with 10 blinks. If I unplug the white connector on the power board that goes into the back of the panel (picture provided) backlights light up bright for a few seconds then get dimmer, but the set stays on.

If I leave the white connector unplugged and also unplug the small connector going to t-con board (picture provided) the backlights come on and stay bright.

In both scenarios I get a picture with what appears to be some of the colors missing. Scenario 1 gives dimmer picture and scenario 2 gives brighter picture but both have missing colors.

Any thoughts would be helpful. I am not versed enough to repair a board but can change a board if I know what the problem is. I can use a multimeter with some limitations.







With the larger white connector plugged into the top of the power board, it always goes into shutdown mode with 10 blinks.

[neilc6]

Re: Panasonic 37” LCD LED

I googled and found your service manual. They usually contain troubleshooting steps for the blink code.

[Mmatt]

Re: Panasonic 37” LCD LED

I found a service manual and did some testing with a multi tester. I found the white connector CN01 that I unplugged to keep the backlight on is not receiving correct voltage. Pins 1 and 12 are getting 172V. The remaining pins 3, 4, 5, 8, 9 and 10 should get 79v but are showing only 1.4v. When plugged in it causes a shutdown. Does this mean the inverter that powers the LEDs is bad?

The manual also says 10 blinks points to ZWEI2 sos on t con board.

[R_J]

Re: Panasonic 37” LCD LED

Pins 1 & 12 are the LED supply voltage, 172v is likely correct, the other pins are the led string return lines, I would check the return line voltage on each of the 6 strings (with the led's connected) as the tv is turned on (and before the protection cuts in) I suspect one of the lines will check different indicating an open led string.

[budm]

Re: Panasonic 37” LCD LED

Pins 1 & 12 are the LED supply voltage, 172v is likely correct, the other pins are the led string return lines, I would check the return line voltage on each of the 6 strings (with the led's connected) as the tv is turned on (and before the protection cuts in) I suspect one of the lines will check different indicating an open led string.

+1
Check the return lines with ref to circuit ground.

[Mmatt]

Re: Panasonic 37” LCD LED

I checked all the pins on CN01 and CN02 when tv powered up and before shut down. Pins 1 & 13 on CN01 and pins 1 & 12 on CN02 were 174v. All others were 158v. I didn’t see one that gave a different reading. The manual says they should read 79v.

[budm]

Re: Panasonic 37” LCD LED

I checked all the pins on CN01 and CN02 when tv powered up and before shut down. Pins 1 & 13 on CN01 and pins 1 & 12 on CN02 were 174v. All others were 158v. I didn't see one that gave a different reading. The manual says they should read 79v.

Are you testing the return lines using circuit Ground (chassis) as ref ground for the meter's Black probe as suggested?

[Mmatt]

Re: Panasonic 37” LCD LED

If you are asking if I'm grounding the black probe to the television chassis, yes I am.

[Mmatt]

Re: Panasonic 37” LCD LED

The tech manual says pin 5 on A03 sends 3.2v to tv sub on. I am getting only 2.7v on pin 5 to tv sub on. Could that cause the tv to shut down when LEDs try to come on?

[Mmatt]

Re: Panasonic 37” LCD LED

After rechecking, the tv sub on at pin 5 is 2.3v

[dick_barton]

Re: Panasonic 37” LCD LED

If your Relay_5VS is present at connector A03, Pin 3, then TV_Sub_On is OK

[Mmatt]

Re: Panasonic 37” LCD LED

Dick Barton, thanks for the reply. I will check pin 3 when I get home from work and post back around 4:30-5:00

[Mmatt]

Re: Panasonic 37” LCD LED

Sorry I didn’t post back earlier. Got sidetracked with car trouble. Pin 3 on A03 has 5.97v

[Mmatt]

Re: Panasonic 37” LCD LED

Here's an update now. This morning I noticed I left the tv on with the 10 blinks going all night. Now I have standby power only. No relay clicking on the power board and turning it on as before. It goes straight to shut down and blinks 10 times. I get 5.9v on pin 3 and 2.3v pin 5 on connector A03 on main board. I have 5.9v on pin 11 of connector CN03 of power board that looks like it should turn on DTV 12v but I'm getting 0v to pin 4 on CN03.

Before all this the power board was clicking and backlights flashed on then went into shut down. Has the power board failed?

[nomoresonys]

Re: Panasonic 37” LCD LED

Maybe look over your solder joints with a sharp eye, give m a wiggle test, see if any are bad/cold, can google bad joint images if needed.