Panasonic TX-L32C4B 3 LED flash

[diif]

Hello, I'm back on this one again, but with more of an idea of what i am doing.
This TV has the standby LED flashing 3 times.
I have measured the voltages on P2 and get 3.3v at pin 4 and 5.5v at pin 12 but nothing else.
Should i have more voltages on P2 ?
Thank you.

[Andrew F. Ali]

Re: Panasonic TX-L32C4B 3 LED flash

Please list the labels on each pin of P2. e.g pin 2-PS-ON. pin 6-BL-ON, etc

[diif]

Re: Panasonic TX-L32C4B 3 LED flash

There is no label and no such markings on either end.

I have taken some readings and am wondering if i have a faulty ic.There are two of them and they seem to be operating differently.

Q7503
S 17.03v
G 17.00v
D 1.28v

Q7504
S 5.66v
G 359mv
D 5.66v

I've read that 3 flashes is over voltage and am wondering if one of these is the cause.

[fzabkar]

Re: Panasonic TX-L32C4B 3 LED flash

I'm still downloading it, but this looks like the service manual:

https://cdn.badcaps-static.com/pdfs/...b43267f815.pdf

[fzabkar]

Re: Panasonic TX-L32C4B 3 LED flash

have taken some readings and am wondering if i have a faulty ic.There are two of them and they seem to be operating differently.

Q7503
S 17.03v
G 17.00v
D 1.28v

Q7504
S 5.66v
G 359mv
D 5.66v

Q7503 is off, Q7504 is on. This is correct, according to the VGS voltages.

[diif]

Re: Panasonic TX-L32C4B 3 LED flash

Thanks for the manual and confirmation the ICs are working.
I shall work through the manual after i have translated it.

[diif]

Re: Panasonic TX-L32C4B 3 LED flash

The 3 flash is "SOS tuner power source"
I measure the STB as 5.66v slightly lower than the 5.8v the manual says.

I have just been plugging it in and measuring the voltages before the self test kicked in.
I put my meter on the 16v pin and the set powered on !! is that a coincidence ?

I am only measuring 16.7v however not the 18v i am expecting.

[budm]

Re: Panasonic TX-L32C4B 3 LED flash

If you look the diagram you see pin 6 is labeled as 16V but as you can see TP2014 is P15V not 16V.
The 18V for sound is not tightly regulated because the power amplifers do not require tightly regulate power supply to function.

[budm]

Re: Panasonic TX-L32C4B 3 LED flash

"The 3 flash is "SOS tuner power source"
The switched tuner6V (5VS) is fed by switched MOSFET Q7504 which is driven by the circuit as I have noted in the PDF.
Switched Q7503 for the switched 16V (15V) is turned on by the TV_SUB_ON signal.
So are you missing the switched TUNER6V when you get the 3-Flash?
If you are then I would check those resistor in the AC detector section, especially those 2.2M resistors.

[diif]

Re: Panasonic TX-L32C4B 3 LED flash

Thanks a lot budm, that's very helpful.
I applied some freeze spray around the optocouplers and the board above and below p2 as Q7503 and Q7504 are behind that bit and the tv now turns on.
I shall leave it on to see if it stays on, turn it off tonight and check those resistors in the morning when its properly cooled down.
Thanks again. I shall report back.

[diif]

Re: Panasonic TX-L32C4B 3 LED flash

The resistance should be the same whichever way i have the probes ?

I measured the 2.2M resistors (R7306, R7308 and R7310) and get 2.18M one way but am measuring 1.9M if i switch the probes around. Any idea what's going on ?

[budm]

Re: Panasonic TX-L32C4B 3 LED flash

So far the resistors are not the problem at this point based on your readings, I am looking to see if those 2.2M go up in resistance which will cause the Transistor not to turn on, so what you are seeing is fine.

[diif]

Re: Panasonic TX-L32C4B 3 LED flash

I've had another more concentrated look at this tonight and understand your notes.
I am measuring 5.57v at pin 1 when i get the 3 flash and 3.29v at pin 9 INV_SOS.
Spraying with freeze spray doesn't seem to be aiding in the the turning on now.

[budm]

Re: Panasonic TX-L32C4B 3 LED flash

So your Tuner Voltage is OK and present at pin 1 of the connector, but the error is saying that The 3 flash is "SOS tuner power source" so I do not know why you are getting 3-flash when the Voltage is present.
"3.29V at pin 9 INV_SOS." I am not sure what the Voltage should be at this pin when TV is normal. I need to look at the service manual in details.