Panasonic TX-P42G30E green light blinking, no video, no audio

[ItepK]

Hey everyone!

I've gotten this TV for free, neither have it seen a TV repair man, neither have it been opened before.

This post describes my entire troubleshooting process of this TV.

When I turn it on using the ON/OFF switch at the side of the TV, the light rapidly flashes green, then it stays on, but it does not react to any of the remote buttons, side buttons, and doesn't play audio.

I've taken the unit apart, and I've started to check some voltages:

• On the P11 connector, there is 15V DC only for a brief moment, then it goes back to 0V
• On the P2 connector, there is 200V DC, then it quickly goes away, like a capacitor discharging
• At the lower right side of the board, there is 5V DC for standby (I assume this powers the LED)

I've asked somebody about this, and they've said that in order for these voltages to show up, the P board has to get a signal to send these voltages, but I'm doubtful about this.

I've also made a video about the sound of the P board when it's turning on, I assume this "oscillating" sound comes from the relay, and I'm not sure if it's normal. (quiet video, please turn the volume up)

The first and last clicks come from the ON/OF switch, the sound at the middle is the supposed relay sound.

The first thing I've started testing was the P board. I've tested (soldered in-place, with diode tester function on the multimeter):

• the fuses
• every diode (Schottky, Zener, Normal)
• every transistor

But they all turned out fine, there were no shorts present.

I've also tried running it with the right and left boards disconnected, but the only thing changed was the voltage at P2 didn't discharge as quickly as before.

Next, I've moved on to the VSUS board on the left.



Using the same procedure, I've tested every:

• IGBT transistor (had to peel off the heatsinks)
• MOSFET
• Diode (Schottky, Zener, Normal)

But there was no obvious short-circuit.

One thing I've noticed is that:



The tracks on that board marked with red are shorted, but I'm not sure if that's normal

I've repeated the same procedure for the other boards, but I've gotten the same result.



Every capacitor on the board has no obvious signs of bulging.

My last suspect is the A board, but I have no sufficent knowledge to test it.

Since I can't figure out the problem, I'm asking you guys for help. I'll appriciate every useful answer!

Thank you for reading it!

[lotas]

Download the service manual for your model and see what error code the LED blinks and what the fault is, in which module....

[ItepK]

Download the service manual for your model and see what error code the LED blinks and what the fault is, in which module....

Doesnt't this section only apply to the red blink codes? My TV only blinks green rapidly for some time, then it stays on.

[nomoresonys]

Maybe try a simple hairdryer test, heat the electrolytic caps up with hairdryer for a couple minutes then try tv, see if there's a brief change, don't wait for it to cool down, try it while it's still hot. Start with powerboard, no change, move to other boards with electrolytic caps and do the same.

[ItepK]

Maybe try a simple hairdryer test, heat the electrolytic caps up with hairdryer for a couple minutes then try tv, see if there's a brief change, don't wait for it to cool down, try it while it's still hot. Start with powerboard, no change, move to other boards with electrolytic caps and do the same.

The hairdryer test did not work, but thank you for the suggestion!

[Diah]

if FANs blocked or damage TV will not start.

[ItepK]

if FANs blocked or damage TV will not start.

The fan is fine, I've just checked it

[nomoresonys]

Post a good picture of the whole back as to see how everything is connected.

[ItepK]

Post a good picture of the whole back as to see how everything is connected.

Here is the best picture I could take:

[nomoresonys]

Check the solder joints on the powerboard if you have not, search bad/cracked/cold solder joint images if needed, first things I suspect with that fluctuation is electrolytic capacitors or voltage regulating diodes, the hairdryer test will only work on a marginal cap if they are too far gone it doesn't work. Remember they don't have to look bad to be bad.

[ItepK]

Check the solder joints on the powerboard if you have not, search bad/cracked/cold solder joint images if needed, first things I suspect with that fluctuation is electrolytic capacitors or voltage regulating diodes, the hairdryer test will only work on a marginal cap if they are too far gone it doesn't work. Remember they don't have to look bad to be bad.

I've looked, but all the solder joints are perfect. I've even reflowed some which seemed bad.

I'll try recapping it after christmas, let's see how it goes...