Panasonic Plasma TX-P50C10E single blink

[toty79]

Hi to all the friends of the forum and well found, first of all congratulations for the forum and wonderful, I read for many years but this and my first thread I hope you can help me and thanks in advance.

Meanwhile, I try to attach the GPH12DE chassis diagram, as the title of this TV on power-up attempts to start with fast green LED flashing and then switch to red led with a single flash at infinity, I read various discussions about it..but no definite solution , from what I have read I have done various tests, knowing that it could be the card to lack, fast test of the voltages on the P "LSJB1279" I find only the STB5V to pin 5 of the connector P7, to the ignition on F_STBY_ON of which pin 6 (P7 ) appear momentarily the 3.3v to then fall to 0V and turn off the Psu, disassembled P card checked all electrolytic diodes etc. nothing in short, I did the bench test of the psu as described in various posts, resistance from 1k between pin 5 and 6 on P7 and 1k resistance between pins 9 and 11 on P25, connected lamps in series on the Vsus output, and direct bridge on P34 pins 1 and 3, well the psu turns on and all the voltages are regular as shown on the nameplate, then board P excluded from fault, I know that at 99% the fault is on the A and vor rei groped the repair as the card is almost impossible to find, TNPH0782-3A, as you already know SOS1 unknown error from panasonic, I'm quite equipped with hot air flow, multimeter and digital oscilloscope, any advice on what to check on the A board and well accepted, from my tests I realized that the 3.3v return from A on P called Panel_main_on are completely absent at 0v and never rise, or read that someone has managed to isolate the defect losing some functions already would be a good step, I ask for help to you more externally to try to repair the mainbord, thanks to all those who join the discussion, you are an extraordinary forum
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[Unspun01]

Re: Panasonic Plasma TX-P50C10E single blink

Hi toty79:

1x blink on Panasonic plasma often means communication error on I2C bus. I2C bus is for communication between any chips that communicate together on the same bus. Look for missing supply voltage or faulty chip connected to I2C bus. (I2C is called IIC in this manual)

I had a 1x blink error on TNPH0831 board and fixed by replacing 8-pin SOIC EEPROM IC9304 from another A-board with other physical damage.

You have a different board so you have different part numbers and functions.

From the manual I see IC1101 EEPROM on top side and IC9001 and IC8601 EEPROM on bottom side. These are good candidates for 1x blink error.

Of course, it could be any other chip communicating on I2C bus, but on my TV it was EEPROM.

For your information, you can force a 1x blink on a working TV by temporarily bridging pins 5 (SDA) & 6 (SCL) of one of those ICs with a meter probe when turning on the TV and the TV will give an error because it cannot communicate.

If you figure out which EEPROM is the issue, you can replace it with another one that is programmed the same.

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Hi Unspun01 thanks for responding quickly

How can I check the IIC bus if it is powered .. which IC and which pin?

Yes and as you say, there are N3 eeprom an upper side IC1101 and two lower side IC9001 and IC8601, from which 3 do you start with jumper pins 5 and 6?
Should I keep it short for bad weather or leave it even after turning it on?
what behavior of the led should I expect? I'll do some tests in the evening
thank you so much

[Unspun01]

Re: Panasonic Plasma TX-P50C10E single blink

I do not know how to properly test the I2C bus but it would require special equipment to understand what data is being passed to and from different ICs.

Here are a few basic tests.

If you assume the ICs are good, and assume they are only missing Vcc, check datasheets for each EEPROM or I2C device to see if you have supply voltage. If Vcc is missing, then even if EEPROM is good, it will not turn on.

With digital multimeter, if you have good Vcc (3.3V), then I often find that pins 5 (SDA) and 6 (SCL) seem to measure about 3.3V also. This is not a true test, but if one of those ICs is shorted or grounded, or not consistent then you might have found the problem. You may also have to read the contents of the EEPROM and see if they are good/bad.

...from which 3 do you start with jumper pins 5 and 6?

You do not have to short pins 5 or 6. I was only stating that on a working Panasonic A-board, if pins 5 and 6 are shorted when you apply power to turn the TV on, then you will get a 1x blink error. That was how I figured the problem was in I2C bus and led me to test and replace the faulty EEPROM.

At the start I did not know which EEPROM was the problem in my TV. I only knew that EEPROM could be one of several things that could cause 1x blink. It was some trial and error. I replaced 2 EEPROMs with no change and when I replaced the 3rd (bad) one the TV worked...

My repair was successful, but required a programmed EEPROM from the same position of similar board. If you have access to another EEPROM from similar board you may have luck. Otherwise you may have to program one yourself.

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Hello forum..update

I tried the short on the three eeprom circuits one at a time and the result does not always change a flash

then I set out to measure the voltages on IC1101 stable voltage and 3.3v upper side ok
instead lower side on IC9001 and IC8601 the voltage rises to 3.3 momentarily to then fall, I state that these measurements were made only with card P and card A connected to each other and all the others detached, I think it is a mistake because it falls the voltage on IC9001 and IC8601 any ideas? it's normal?
I couldn't figure out where to measure vcc on I2C help and thanks
there is no short circuit on IC9001 and IC8601

[Unspun01]

Re: Panasonic Plasma TX-P50C10E single blink

I tried the short on the three eeprom circuits one at a time and the result does not always change a flash

Please re-read my reply. I never told you to try shorting the EEPROM pins 5-6.

I only said that when I short EEPROM pins 5-6 on a WORKING board, I can create a 1x blink error. That test is how I determined my 1x blink fault was related to I2C BUS and ultimately that I had a bad EEPROM.

Of course it would have no effect in your case with your non-working board.

I couldn't figure out where to measure vcc on I2C help and thanks

I2C is a SERIAL DATA BUS. I2C is for communication and transmission of SERIAL data input and output. It is NOT a power bus. It is not Vcc. But each IC connected to I2C bus is powered by Vcc. Therefore you need to find datasheets for I2C connected chips and see if each IC has good Vcc.

Also, each I2C data and clock bus line (SDA and SCL) is pulled up to Vcc with a resistor. That's why I told you to check voltage at pins 5 and 6. If they measure close to 3.3V then there is no short on SDA or SCL lines, but still could mean a bad EEPROM.

Read more about I2C here:
https://i2c.info/

You will need to find a way to replace each EEPROM one-at-a-time to determine which one is the problem.

You can replace pre-programmed EEPROM ICs from a donor A-board, or maybe someone with same TNPH0782 A-board can upload EEPROM.BIN for IC1101, IC9001, IC8601 and you can re-program EEPROM yourself.

You uploaded the SERVICE manual. You have the information where to check Vcc. Each of IC1101, IC9001, IC8601 have Vcc at PIN 8. But you also need to check ALL ICs that communicate on I2C like the processors, ram, etc.

Honestly, check all of the high-lighted power rails in the service manual you have. They are probably ok, but check them anyway. If you get stable 3.3 voltage, or 3.3V appears then disappears, your power rails are probably ok but CPU detects error and shuts power off.

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Hi forum hello Unspun01

sorry but being in Italy I use a translator who sometimes doesn't translate very well
however I tried the short on eeprom just to understand if the flash code changed it was just curious
I read your link .. for something new I never repaired this section of the circuit so I will still learn a lot but still before testing the vcc of each ic I wanted to try to reprint eeprom, unfortunately I don't have any other A boards from panasonic , so I have already prepared new virgin memories on which to write the content of the old eeproms, I forgot how Unspun01 says on eeprom pins 5 and 6 it turns 3.3v voltage when it works properly, I ordered CH341A programmer which we hope will be good ... I keep you updated and thank you

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

sorry guys but I discovered I at least hope .. a short circuit on 3 smd capacitors next to the A25 input connector coming from psu ... I attach photos of the three capacitors ... according to you and normal? the whole area around and below does not have short circuit, but only the three leads that I am attaching in the picture ... is it possible that they are the problem?

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

sorry guys but I discovered I at least hope .. a short circuit on 3 smd capacitors next to the A25 input connector coming from psu ... I attach photos of the three capacitors ... according to you and normal? the whole area around and below does not have short circuit, but only the three leads that I am attaching in the picture ... is it possible that they are the problem?

the layout of the A25 connector and on page 63 of the service manual

[R_J]

Re: Panasonic Plasma TX-P50C10E single blink

Those are filters, How are you checking them, they will check shorted end to end, check each end to ground, that should be open.

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

R_J Thank you for answering

in fact I had strong doubts, they seemed to me fuses being screen-printed FL ... anyway and as you say, I measure short between the two poles of the filter, but then there is no short towards the ground so everything is ok, waiting for the programmer to arrive and reprogram eeprom. .if there are other tips they are well accepted ... thanks

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Hi all friends of the forum

Finally the CH341A programmer just installed and tested works perfectly, now my questions are how to operate?
1) should I read every eprom save the file and rewrite it on the eprom itself?
2) do I have to read every eprom save the file and rewrite it on new memories?
3) if one of the files is corrupt?
does anyone have these files already saved?
The specific memories are 24C08-24C16 and 24C64 on sheet A TNPH0782-3A, thanks to all my friends and I hope you can help me get started

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Unspun01

I read your post about the exchange eprom ic9304 on the card A TNPH0831 successfully, you wrote that caused the error sos1 was on the bottom of the card, on my card A in the lower part there are two IC9001 and IC8601 memories for which case series was the faulty eprom?
24C08?
24c16?
24C64? thank you all

[Hombre]

Re: Panasonic Plasma TX-P50C10E single blink

I think i have some similar tv, if i am not mistaken it is tx-p42x10, but same generation, hd. The problem is i am not at home right now, coming back in 10-15 days, so please remind me in 2 weeks, and i will try to save eeprom from that one, maybe it will work.

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Thanks Hombre, the tx-p42x10 if I am not mistaken it mounts a shed A tnph0783, besides being of the same generation and also very similar as a card, thanks I wait for your return to read the files, thanks

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Hello friends
I wanted to ask Hombre if he came back to read the eproom files, thanks

[toty79]

Re: Panasonic Plasma TX-P50C10E single blink

Hi Guys and spent some time but I'm still looking for files ... can anyone help me ..?
also a similar model could work?