Sony KDL-37EX402 the TV in dead, no LED, motherboard problem.

[yoritomo]

Hello

The TV does not show any sign of life , I started the troubleshoot as this , no power Led, no reaction when pressing the power button.

I checked the Power coming out from the power supply, the 3.3V_standby is correct and steady, then I checked the 1.2V_standby produced by IC6001 which Is good as well.

So I decided to control the main IC , IC4000 , he does not output any oscillation on the Xtal, Then I am now bloacked there.

The schematic is downloadable at Eletrotanya website , the schema is weird because the processor is not represented with any Xtal output, but obviously it has one.

Thanks you for your hint and help.

[lotas]

Yes but I don't have any more good sources for dumps, before I had a pro subscription to Euras services, but it is finish now. I could not find it in download,

Try... (Nand +Spi)

[nomoresonys]

Maybe start with powerboard, simple first, check over and reflow any solders on bottom of board that looks suspect, sometimes they look fine but are not. Also check all diodes and resistors on top of board.

[nomoresonys]

You can put links to schemo's here, not many have time to chase them down, help others help you.

[yoritomo]

Hello

Thank you for the replies, yes sorry, there is the link to the schema below. The power supply works fine, but the processor never orders the main power to start by the POWER_ON pin.
https://elektrotanya.com/showresult?...=&kat2=all
Be careful in this schematic, it is a bit weird the main chip is diplayed in many pages in it's different sections.

I have some new informations, I have been in the wrong way due to the malfunction of the test lead of the oscilloscope, actually the processor is running, I could see the oscillation in proper frequency. The reset circuit is working.
I then decided to check the keyboard , but the power button is powered and works fine also. No power is going to control any of the 4 front LEDs.

I start to have some doubts about the NAND chip firmware. Perhaps a good bet to try flashing it.

Have a better day than here, it is a storm with heavy rain ...

[lotas]

I start to have some doubts about the NAND chip firmware. Perhaps a good bet to try flashing it.

In addition to nand, there is also a spi flash IC4104_M25P10A.

[yoritomo]

Yes but I don't have any more good sources for dumps, before I had a pro subscription to Euras services, but it is finish now. I could not find it in download,

[lotas]

Yes but I don't have any more good sources for dumps, before I had a pro subscription to Euras services, but it is finish now. I could not find it in download,

Try... (Nand +Spi)

[yoritomo]

Thank you so much for these dumps, may I ask where did you find it ?
I wanted to flash IC1404, but it is not even readable or detectable by the programmer, the chip is dead I will order a new one, I don't have it in stock or salvage unluckily.
The number of the NAND chip number does not match with the number of the file you sent.

[lotas]

Everything should match, what doesn't match with you, where, post a photo, programmer log....
Nand:IC4704=H27U1G8F2BTR
SPI Flash:IC4104=M25P10

[yoritomo]

Yes sorry, you are right, I was watching in the schematic, there the number is not the same, but on the PCB the IC number is matching.
I will come back with some news when I will receive the small chip.

Have a nice day .

[yoritomo]

Hello, I have some news, due to the continuous strikes of the post services here in Belgium, I just received the chips yesterday from Amazon. Cheap and I ordered 5 and I got 8 .... by the way I doubt all of them are really working , you know what I mean.
Anyway, the first one I tried, was flashed with success and the TV set is now working fine just replacing IC4104.

Thank you again for your help.

[lotas]

OK!