Panasonic TC-P42S30 Red Standby comes on - nothing else

[jstiene]

Hello.

I received a Panasonic TC-P42S30 from a friend. The problem is as follows:
If I try to turn the TV on with the power button, nothing happens. I opened up the keypad and it seems the power button "contact" is damaged. So I then used a Panasonic remote to turn the TV on. When I turn it on, the RED led lights up, but nothing else happens. no sound or video. I hear a very faint click coming from the power supply. Also, I cannot then turn off the tv with the remote. In other words, I can turn it on but not off. No blinking error codes.

Is it possible the power button was damaged causing this problem or is it unrelated? As anyone else encountered this problem on this model tv?

Any help would be appreciated!
Happy Thanksgiving to all!
Joe

[sordids999]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

https://www.badcaps.net/forum/showthread.php?t=39740

[tw2005]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

turn it off, take the back off, disconnect SN2 and SN20 and see it it starts but then 7 blinks. Let it sit for a while before you reconnect sn2, 200v residual could be present for a while and may spike the board which may be damaged anyway

[tom66]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Tw, just a note, on my U30 when I unplugged SN2 it would just sit there with green light, and no picture. No error code.

SN2 plugged in (shorted) resulted in green light then no light. This is UK model though, so may be different.

[tw2005]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Tw, just a note, on my U30 when I unplugged SN2 it would just sit there with green light, and no picture. No error code.

SN2 plugged in (shorted) resulted in green light then no light. This is UK model though, so may be different.

With SN2 removed, was that when working or when it was faulty and you were fault finding?

I'll have to have a look at a guide i think is for your / our markets) interesting.
I suspect US is different but by rights with both those removed it should generate a code if the Sc is at fault.

Currently sounds like lock out due to short

thanks for the info.

Shutdown but No Blink code – Power LED stays on (Check for Shorted Vsus* / Vda** / P15).

[tom66]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

That was when faulty. If Vsus "pinked out" due to the series bulb, a 6 blink code might occur. Or 7 blinks if during dark scene with short sus periods.

[jstiene]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Hello. And thanks for the quick help. So I unplugged SN2 and SN20 and turned power on. I then received an 8 blink code. Double checked to make sure it was not 7 blinks. Then waited over an hour and plugged back in with same results. TV RED standby light goes on when I turn on with remote, but no other response...sound..video..nothing...

any suggestions where to check next?

Thanks!

[tw2005]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Hello. And thanks for the quick help. So I unplugged SN2 and SN20 and turned power on. I then received an 8 blink code. Double checked to make sure it was not 7 blinks. Then waited over an hour and plugged back in with same results. TV RED standby light goes on when I turn on with remote, but no other response...sound..video..nothing...

any suggestions where to check next?

Thanks!

yep,it was going to be either 7 or 8 it did not matter , point being you now have a blink code. You have a failed/shorted SN board

Replace or have ModuslinkPTS repair

Very,very common and plenty of threads about it and also watch out for poor earth or loose screws with these boards.

[tom66]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

I'd say repair on these is very easy if you can do basic surface mount work. 5 SMD transistors, plus one small MSOP10 + SOT25... the last two are the hardest but they don't always fail so you might be lucky. The SMD transistors are piss-easy.

[jstiene]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Thanks for the feedback. So quick question on surface mount soldering..I would say I have good soldering skills going back 25 years but I am not good at surface mount removal. Is there is a specific soldering iron or method to doing these? I have a few boards that I can learn on. Everytime I damage the traces..any suggestions to be more effective?

also, which are the 5 SMD transistors that need to be replaced?

Lastly, is there a way to disconnect power/signal to the board to verify that the main board, sound etc is still functioning properly or does this model require all boards active to power up?

[tom66]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Well, the main requirement is to have a soldering iron with regulated temperature - that means it won't overheat the board. A lot of cheap soldering irons don't regulate the tip temperature so it's easy to apply too much heat. This is different to an iron with a variable temperature. It needs to actually switch on and off the soldering iron. If your iron has this feature, typically it'll have an LED which will flash on and off as the iron is heated. The main reason pads get lifted is heat. In fact that's really the only good reason. There's glue bonding the copper layers to the fibreglass core. If you debond the glue, good bye pad.

Taking the transistors off does require some heat. I prefer to chop the small legs at the bottom as they're easily accessible. I then apply heat to the tab, it takes a minute or so per transistor, but eventually the solder will become molten and you'll be able to simply lift the transistor off. The pad should be cleaned/wicked before installing the new transistor.

Installation is easier: Apply a small amount of solder to the pad where the transistor will go, and heat the pad up with the iron so it becomes molten. Slide the transistor on from one end, until it covers the whole pad. If you do this quickly, the transistor will get an even solder coating underneath which is important for heatsinking and reliability. Watch out for bubbles or solder squidging out of the sides. Then, solder the two legs.

The exact parts: You should test the transistors for shorts. On my board, it was:
4 x 30F131 (Q401,402,421,422)
1 x DG302 (Q441)
2 x Rohm Gate Driver (IC501,502)
2 x Dual Transistor (Q501,531)

However every board is different, sometimes DG302 does not fail, or two DG302s fail, for example. If the DG302 is good, the gate drivers are almost certainly OK and don't need to be replaced. I would not recommend a novice try replacing those.

[jstiene]

Re: Panasonic TC-P42S30 Red Standby comes on - nothing else

Thanks for the advice. I am going to pick up a regulated soldering iron as you mentioned and give it a try. Looks like the kit is $20 so not too expensive if I fail during my learning curve. Any recommendations on a specific iron or just make sure its regulated..?