Panasonic TC-P50C2 No Power

[1beertap]

Forum Members,

I don't work on plasma TVs very much but, this TV doesn't turn on and shows no LED coming on, it's completely dead. I have checked for standby voltage of 5v, at the P board and going to the A board; it test okay. Since, there is 5v going to A board but no standby LED, I would assume that the A board is at fault. Am I correct or should I check for something else? Also, any idea where to find suffix on the A board?

[tw2005]

Re: Panasonic TC-P50C2 No Power

Expecting Rev Av, have a look at the pink highlights in the SJ pic. STB 5v and no LED is sounding A board as the 3.3v is generated on the A for the LED and other voltages. Any relay clicks when the TV is plugged in and power turned on?

These also have a common failure on the TNPA5072 SS asthey go dead short and also Sc board, I'd have to do some looking to see what version it is. I have the 42" but it has a SN , combined Sc/sd/su, but also suffers from TNPA5072 failure.

Just got to help someone else ATM, a little busy , must be fix my telly day.

http://www.shopjimmy.com/media/catal...nuus-top_1.jpg

[1beertap]

Re: Panasonic TC-P50C2 No Power

tw2005,
Thanks for the reply. No relay clicks are heard when plugging it in or when power is turned on and yes, as per your info, the A board is Rev. AV

[tw2005]

Re: Panasonic TC-P50C2 No Power

tw2005,
Thanks for the reply. No relay clicks are heard when plugging it in or when power is turned on and yes, as per your info, the A board is Rev. AV

I'm going to say A board is dead. What happened whenit died or is this a Tv purchased for repair?

Before you start tipping money into this, I'd be checking the SS and Sc for short cct at SS11 and SC2,

I have a feeling these A boards are hard to find and expensive, Moduslink do repairs.

Do you have manual and schematic to follow and confirm voltages?

I was about to look for a training guide , been swamped this morning pMs and all.

[tw2005]

Re: Panasonic TC-P50C2 No Power

manual.

just realised this is one I have not found a training guide for. I have the C1 series which is similar to a point but won't be 100% accurate,

This is from the S2 FHD series

"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 P7 (Pin 1).
The STB5V from pin1 of connector P7 is applied to a 3.3V regulator to power the Main CPU (IC8001) on the A board. This energizes and prepare the microprocessor (CPU) for program execution.
The 3.3V from the voltage regulator 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).
If the STB5V is missing, the TV is dead (No power)"

even if sc or SS were shorted it would not affect this stage, comes into play when the Tv starts, yours is not even able to initialise by the sounds of it.

[tw2005]

Re: Panasonic TC-P50C2 No Power

http://www.moduslinkptstvboards.com/TXN/A1LNUUS/

[tw2005]

Re: Panasonic TC-P50C2 No Power

I've always been interested to learn more about A board faults.

If you want , confirm you have 5v at pin 25 of IC9004, confirm no STB3.3v at pin 8, measure resistance pin 8 - gnd.

If say IC9004 was the only fault, it's a $4 chip

http://www.partsimple.com/c1zbz0003983-msc-n-13.html

[1beertap]

Re: Panasonic TC-P50C2 No Power

Before you start tipping money into this, I'd be checking the SS and Sc for short cct at SS11 and SC2,

I checked SS11 and SC2, no shorts found at either connector pins in relation to ground or each other.

If you want , confirm you have 5v at pin 25 of IC9004, confirm no STB3.3v at pin 8, measure resistance pin 8 - gnd.

I checked and confirmed that 5v is at pin 25 of IC9004. Also, I confirmed that STB3.3v not at pin 8. Lastly, I measured a resistance of 22k ohms across pin 8 and ground. Thanks

[Ltank]

Re: Panasonic TC-P50C2 No Power

You have 5vdc standby. Does the mainboard send a PS-ON command back to the P.S. to turn it on?

[tw2005]

Re: Panasonic TC-P50C2 No Power

interesting, so I wonder if just that IC needs replacing? I grabbed another A board I have with a different ASIC but same job, and had 8k. Certainly not shorted.

I have a 50GT25 board with same ASIC and blk lead on gnd and red on 8 it charges and resistance settles at about 45k, reversed and it is 24.4k.

I might see if I can jerry rig 5v on the stb from a power source and see what happens. Could take me a while

[tw2005]

Re: Panasonic TC-P50C2 No Power

interesting, so I wonder if just that IC needs replacing? I grabbed another A board I have with a different ASIC but same job, and had 8k. Certainly not shorted.

I have a 50GT25 board with same ASIC and blk lead on gnd and red on 8 it charges and resistance settles at about 45k, reversed and it is 24.4k.

I might see if I can jerry rig 5v on the stb from a power source and see what happens. Could take me a while

Ok, So I just hooked up a 5v source to stb5V and got 3.3V. Not sure if that's conclusive enough though or if there is anything else that could shut that off but since it powers the front led as well which is on in standby, i'm thinking not.

The 3.3v stb is not short and your measurement is comparable with mine so if I could get another ASIC for that for $4 it's worth a shot.

[tw2005]

Re: Panasonic TC-P50C2 No Power

do you have a way of supplying 3.3v to pin 8 or another spot equivalent in the same cct. maybe pin 8 of eeprom IC9001

I'm thinking a twin AA battery holder may get it close enough , be funny if it started doing this.

[tw2005]

Re: Panasonic TC-P50C2 No Power

Might be a bit more to it yet, there's another asic for 3.2v and 1.2v for the micom

[tw2005]

Re: Panasonic TC-P50C2 No Power

Actually, this may be a little more complex, there's also another ASIC IC4700, for 3.3V & 1.2 V for the micom. mayhave to check that one to and see if 5vstb in and 3.3 & 1.2 out.

Missing 3.3v on the other IC9004 would be an issue , may need some other help here if anyone has gone this deep into the A board.

[tw2005]

Re: Panasonic TC-P50C2 No Power

Yeah, I'm really muddled up, the asic I have is not the same and looks like that one we tried may need a signal fom another. the LED is powered via ic8001

[tw2005]

Re: Panasonic TC-P50C2 No Power

IC4700, see if 5v stb at pin 7, 3.3v out at pin 8, 1.2v at pin 6

[1beertap]

Re: Panasonic TC-P50C2 No Power

I have 3.3v at pin3 on K board going to power LED. I think IC8001 is suspect since it controls the grounding side of the LED.

IC4700 has all good voltages.

IC9004 just doesn't have 3.3v on pin 8, in which is a problem. I applied 3.3v to pin 8 and nothing happened which leads me to believe that IC8001 has a problem as well.

[tw2005]

Re: Panasonic TC-P50C2 No Power

I have 3.3v at pin3 on K board going to power LED. I think IC8001 is suspect since it controls the grounding side of the LED.

IC4700 has all good voltages.

IC9004 just doesn't have 3.3v on pin 8, in which is a problem. I applied 3.3v to pin 8 and nothing happened which leads me to believe that IC8001 has a problem as well.

Starting to seem that way, IC8001 does need the 1.2V if that's there yeah that's where I stop, may have to send it in and get repaired

[lookimback]

Re: Panasonic TC-P50C2 No Power

Any luck with this? I have same symptoms on a TC-P46C2. My A board is a rev AU though. On IC9004 I have 4.5v but no 3.3 on pin 8. Pin 8 to ground resistance 5.5k. On IC4700 4.5v on pin 7. No 1.2v no 3.3v.

[lookimback]

Re: Panasonic TC-P50C2 No Power

Well, I've identified the problem with mine. Found a burnt spot by one of the HDMI ports. I pulled it and a bunch of pads came up with it. There's so much copper on the board that my iron wouldn't cut it. I ended up using my air wand and the thing just dropped out the bottom, taking the pads with it. Oops. I think the problem was in that big bga chip with the heatsink on it anyway and I have no way to rework bga yet.