Panasonic TC-P42S30 - Won't power on or give blink codes!

[Forkbeard22]

Hello, world!

New to the forums. I'd like to try to troubleshoot my TV so that I can fix it, but I can't seem to find anyone with similar problems to mine. Usually if people have a Panasonic plasma TV that won't turn on it will seemingly always give blink codes.

Model # TC-P42S30 Panasonic Plasma 46" 1080p

Things I have tried:
- Checking for blown fuse (none)
- Holding in the power button to try to get a blink code (none)
- Plugging it into different outlets
- Plugging it into different outlets using a different power cord
- Unscrewing the back and looking for busted caps (none)

Looking for any and all suggestions or help available! Thanks in advance!

- Jim

[unxetas]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Does the red (standby) light come on at all? Does it not come out of Standby mode, or is it completely dead with no signs of life?

As soon as you plug it in, the power supply should be feeding 5V to a few other boards.. I'd check first if there are 5v coming out of the power supply..

Not sure how confident you are around electronics, but be careful around the power supply if you don't know what you're up against!

[Forkbeard22]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

I build my own computers, so I'm somewhat confident around electronics. I've never had to solder something yet is my only inexperience I think.

No power light, no standby light that I can see on the outside. Or is the light you're speaking of on the board?

[unxetas]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

I meant the red light that most TVs have while on standby, usually by the power button or something. Really just any sign of life

I would guess there's something wrong with the power supply. Looking at the service manual here

There should be a pin on the power supply labeled stb5v and you should have around 5v there.. This powers the standby LED and the board that contains the power button, CATS sensor, etc.

edit: btw, I won't be able to help much beyond very, very basic diagnostics! Just thought I'd help you check some of the more basic stuff before someone else who really knows what they're doing can jump in and help you fix this

[tw2005]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Some more info. If STDBY 5v is present, IC5000 on the A-board needs to generate 3.3V & 1.2V from the STDBY5V.

There should be some info in the guide that can be applied to this model too.


"When the TV is plugged in:
AC is applied to the standby circuit in the power supply to produce STB5V.
The STB5V is provided to the A board via connectors P6 (pin6).
The STB5V from pin6 of connector P6 is applied to the Analog ASIC (IC5000) to power the Main CPU/PEAKS LDA3 (IC8000) on the A board. The Analog ASIC (IC5000) converts the STB5V to STB3.3V and STB1.2V. These 2 voltages energize and prepare the microprocessor (CPU) for program execution.
The STB3.3V from the Analog ASIC (IC5000), besides being applied to the CPU, is also applied to the remote control receiver and the power LED on the K board through connector A1/K1 (pin 3).When the CPU receives 3.3V and 1.2V, it outputs a command that is provided to the P board. This command triggers the AC relays on the P board and only lasts approximately 15 seconds. The command applied to the P board is called different names, “F-STB-ON,TV-SUB-ON, or TUNER-SUB-ON”. The function of this command is to turn on the circuit that generates the “F15V” in the P board.
The F15V from the P board is applied to the A board through connector A6 (pins 10 and 11). This voltage is applied to several voltage regulators to generates the SUB voltages used by the A board.
If the STB5V is missing, the TV is dead (No power)"

[Forkbeard22]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Thanks for the help so far, all. Sorry for the delay, I had to buy a new multimeter. In the mean time I found some additional advice on things to test. One of them being that if there's no red LED on the TV I should check the fuses on the power supply board. I did that, and I've found 2 fuses that are giving me an open line when I test them. They're fuses F101 and F102 (fuses marked with a pink bar on the lower left of the power supply board image provided by tw2005). The other 3 fuses are testing as closed circuits, apparently functioning properly. Just double checking here, but does this make sense as the answer to my problem? Replace the two bad fuses and away we go?

[tw2005]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Thanks for the help so far, all. Sorry for the delay, I had to buy a new multimeter. In the mean time I found some additional advice on things to test. One of them being that if there's no red LED on the TV I should check the fuses on the power supply board. I did that, and I've found 2 fuses that are giving me an open line when I test them. They're fuses F101 and F102 (fuses marked with a pink bar on the lower left of the power supply board image provided by tw2005). The other 3 fuses are testing as closed circuits, apparently functioning properly. Just double checking here, but does this make sense as the answer to my problem? Replace the two bad fuses and away we go?

I thought you reported checked fuses none blown in post 1. just replacing them, could try it but usually something has shorted to blow them.

Not sure if they have the PSU schematic in the manuals of these later ones or the res will be poor.

[Forkbeard22]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Sorry, checked the house breaker box I meant. I'm good with words =X

EDIT: So is that a "Yes the fuses are the problem?"

EDIT2: Found a service manual at - EDIT: doesn't show the required fuses.

EDIT3: P-board is listed in the service manual, but fuses are not. It says "Power supply - Not Serviceable - Should be exchanged for service." This has also been my experience with PSUs for my PC. Way too dangerous to mess with if you get it wrong, much better to just replace them whole. Guessing that applies here? Or is this something I should attempt? I've got a soldering iron, just haven't used it for electronics work yet.

[tw2005]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Sorry, checked the house breaker box I meant. I'm good with words =X

EDIT: So is that a "Yes the fuses are the problem?"

EDIT2: Found a service manual at - EDIT: doesn't show the required fuses.

EDIT3: P-board is listed in the service manual, but fuses are not. It says "Power supply - Not Serviceable - Should be exchanged for service." This has also been my experience with PSUs for my PC. Way too dangerous to mess with if you get it wrong, much better to just replace them whole. Guessing that applies here? Or is this something I should attempt? I've got a soldering iron, just haven't used it for electronics work yet.

If the fuses are open cct then there is a problem.

[tw2005]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Go to page 34, block diagram, not complete cct, 250V 10A fuses. Maybe check for shorted FET or resistance test across the mains in on the PSU but on the other sisde of the blown fuse becasuse obviously if you do it at the pins, it's open as those fuses are for AC in.


Edit: diodes and bridge rectifiers, any heat sinked part within the white line "HOT" side of the PSU.

[tw2005]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

Might as well check out the SN board too for shorted SN2 or shorted 30F131 transistors just in case as they're known to blow too. It's d be a bugger if you replaced the PSu to find the SN bad also.

Do you know the TV history or is it a project repair?

[Forkbeard22]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

I've got main power switch pins with resistance, resistance from the main power switch to the standby pin stby5v_on... Testing from the P9 (AC Cord in) Live to one side of the fuses in question is closed circuit, but to the other side of the fuses is open circuit. I'm assuming this is confirmation that the fuses are blown? Not sure what else to test here. Just going down the line after P9 live, the fuse gives open line, but after the fuse it's all closed circuits to L101, L102, C104, NR103, etc.

I'm having trouble seeing on the diagram where the FETs are. There's a lot of them listed on the parts list, but the reference numbers don't lead me to anything on the block diagram.

EDIT: this is a project repair for me... and a big learning experience. It's not been repaired before in its 2.5 year lifespan.

[Forkbeard22]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

SN2 board checks out as fine. Transistors all seem to check out, and the circuit seems to flow unimpeded through the board. Also, the hot parts with heatsinks all seem to check out. All seems to come back to the fuses as the only thing I've found wrong.

EDIT: Well, maybe, maybe not. I can't seem to get a good circuit with the RL102 relay. Nothing looks burnt on the board, but I'm not sure it's just the fuses.

[Ccalxr]

Re: Panasonic TC-P42S30 - Won't power on or give blink codes!

forkbeard have you ordered new fuses yet? if you have trouble finding them let me know, i have a few scrap pany p boards i could pull fuses off of.