SONY KDL-43W755C | 5 blinks stand-by LED

[dominik0801]

Hello guys.

Today I got this TV for free, the friend included a "new" (used) TCON with it, since he told me, that doesn't work either.
With the stock TCON, this TV turns on, stays on, but the screen only has 5 RED vertical lines on it, and that's it.
Backlight stays on and is fine.

With the "new" TCON, the TV turns on, shows SONY logo, some spinning circles, then the TV goes blank, and the stand-by LED is blinking 5 times, won't react to anything.
I have read some forums, where it's been told that the part number is not always enough to be the same, because TCONs might still have different components on them - but they are all the same, triple-checked everything under a microscope.
I have switched all NAND/SPI chips over, in case they have an identification number in them, but that didn't help either.
No missing components.

While the TV is ON (before it turns off with 5 blinks), the picture on the screen is perfect. Not a single bad pixel, line, or whatever.
Unplugging different sides of the screen won't make a difference either.

Do you have any ideas?

[lotas]

Transfer eeprom 24c32 from the original t-con to the new one.

[dominik0801]

Transfer eeprom 24c32 from the original t-con to the new one.

Thank you for your answer, I already done that too, but it stayed the same.

[lotas]

Check these contacts on the LVDS cable to see if they are bent during manipulation and for their cleanliness under a magnifying glass.
Did you re-solder the eeprom well?

[dominik0801]

Check these contacts on the LVDS cable to see if they are bent during manipulation and for their cleanliness under a magnifying glass.
Did you re-solder the eeprom well?

The EEPROM chips were all soldered correctly/good, but of course I resoldered them just in case, its perfect still.
The LVDS cable doesn't have bad pin, and I cleaned it.
Unfortunately nothing changed.

If there is no TCON connected: TV stays on. If the old TCON is connected: TV stays on (even tho it has no NAND/SPI chips on it right now).
With the new TCON, the TV turns off after Sony logo, and 5 blinks.

TCON voltages are all present. Both TCONs show the same thermal characteristics under thermal cam.

I'm out of ideas right now. I attach images of the boards, maybe you can find some differences between them, although I could not.
The top board is the new, and the bottom is the old one.

2 SPI/NAND and a capacitor were missing from the new one, they were placed on from the old one, so it's like a perfect clone of the old one.



Tomorrow I will try some things, if anything pops in my mind.

Thank you.

[nomoresonys]

Probably bad eMMC.

[lotas]

Probably bad eMMC.

EMMC here has nothing to do with error "5", error "5" is a t-con or panel.

[nomoresonys]

I can't count how many times blink codes have been completely wrong, CAN YOU.

[dominik0801]

I have made a short video, where you can see, what the TV is doing, and that the screen looks absolutely perfect, when it's active.

Sometimes, VERY RARELY the TV stays on for longer (like, even 10 seconds) with perfect display, then it goes to 5 blinks again.

Tbh, I am totally new to Sony. Should the TV stay on, if I were to disconnect one or the other side of the LCD from the TCON board?
If yes, then I could rule out the LCD, as the TV turns off even if the LCD is totally disconnected.

[nomoresonys]

Bar codes in pictures are not quite readable, do the 10 letters and numbers match after the first two letters on the white bar codes?

[nomoresonys]

Another possibility is maybe there's a fault on one of the chips you transferred.

[nomoresonys]

Not saying this is not a tcon issue, I just never assume anything just by a blink code alone.

[dominik0801]

Bar codes in pictures are not quite readable, do the 10 letters and numbers match after the first two letters on the white bar codes?

The barcodes are:

New one: TT-5543T02C04-53F-M249754-D4117-02
Bad one: TT-5543T02C04-648-M255040-D5395-02

As I said, the "new" TCON is also an used one, but the person who gave me the TV told me, that the TCON was bought from a local service guy, who asked him about the barcode and TV screen size prior the purchase.
It had no EEPROM/SPI chips, and had a capacitor broken off, so I transfered everything from the bad one, but every other part looks in-tact.

I guess there is no way to turn the protection off - maybe just to see if anything happens?

[nomoresonys]

Maybe check all the capacitors on the new tcon, not sure what they should be but at least make sure none are shorted, if you find any short isolate board and recheck, if you find nothing try the same check on the mainboard caps. Keep in mind that a shorted cap could be an indication of a bad ic and maybe not just a bad cap.

[dominik0801]

Maybe check all the capacitors on the new tcon, not sure what they should be but at least make sure none are shorted, if you find any short isolate board and recheck, if you find nothing try the same check on the mainboard caps. Keep in mind that a shorted cap could be an indication of a bad ic and maybe not just a bad cap.

Cross-measured both TCONs, every diode, capacitor, voltage line, test points, etc..
Everything is identical.
Even current consumption is same to the last decimal (checked with bench psu).
Xtal out is fine too.

So it could be anything I guess.

[nomoresonys]

And did you do those checks I suggested on the mainboard.

[dominik0801]

And did you do those checks I suggested on the mainboard.

Yes, measured capacitors, diodes, and main lines. All good. Thermal cam didn't show any suspicious parts either.
Of course I couldn't cross-measure with another board, as this is the only one on hand.

So we are at the same possibilities, mainboard, cable, tcon, or screen..

Since you said, that the original TCON panelid EEPROM could be also bad.. if that's the case, is there anything we can do, or is it a lost cause?

[nomoresonys]

Wondering if you might need to pair them back up with a firmware update/pair, maybe Diah can help, he's good with that kind of thing, this one is a head scratcher for me, interesting problem, hope someone can figure it out. Me not being a super tech, I would just try another tcon with those matching 10 digits. The replacement tcon makes me suspicious because it was missing parts. I think you also need it to be from the correct screen size but not exactly sure on that.

[dominik0801]

Wondering if you might need to pair them back up with a firmware update/pair, maybe Diah can help, he's good with that kind of thing, this one is a head scratcher for me, interesting problem, hope someone can figure it out. Me not being a super tech, I would just try another tcon with those matching 10 digits. The replacement tcon makes me suspicious because it was missing parts. I think you also need it to be from the correct screen size but not exactly sure on that.

I just read on another page about sony 5 blink: "...after replacing the main board or tcon, youll have to perform a factory software update...", however this is the only page I read this, and is not confirmed.
It might be needed to pair up the mainboard-tcon, but since the EEPROM was transferred over, I don't see the reason here.
Now I began an update, however, without the TCON connected, because when I connect it, it couldn't even start the updating process, went straight to 5 blinks.

The update went through, but didn't change anything either, unfortunately.

Maybe I will try to get another TCON and cable, just to see.. I'm also not that big of a TV guy either, I am fixing laptop and videocards mostly, but I always love to mess around with free stuff.
The replacement tcon is for this screen size, the TT-55"43"xxx part states, that both are for this 43 inch screen.

(Talking of which - I often repair VGAs and even laptops by changing the GPU/CPUs to whatever compatible I have laying around.. like, yesterday I put a 2070 GPU core on a 2060s PCB, since that was the only one I had laying around, flashed the right BIOS, and it works..
Also, I test laptop LCDs with whatever compatible (lvds/edp) based laptop I have laying around.. I can test whatever sized lcd, as long as the connector is compatible.

How come we still don't have universal LVDS cables for TVs? For instance, let's say, the mainboard in this TV is good, but the screen is not.
Then I have another TV outside, where the screen and tcon is perfect, but the mainboard is not (the customer popcorned the QFU chip before he gave the tv to me). I don't see the point to make the TCON LVDS pinout different, when the screen is the same size, resolution is also the same, voltage, etc.. or is there something like this?)

[nomoresonys]

I just read on another page about sony 5 blink: "...after replacing the main board or tcon, youll have to perform a factory software update...", however this is the only page I read this, and is not confirmed.
It might be needed to pair up the mainboard-tcon, but since the EEPROM was transferred over, I don't see the reason here.
Now I began an update, however, without the TCON connected, because when I connect it, it couldn't even start the updating process, went straight to 5 blinks.

The update went through, but didn't change anything either, unfortunately.

Maybe I will try to get another TCON and cable, just to see.. I'm also not that big of a TV guy either, I am fixing laptop and videocards mostly, but I always love to mess around with free stuff.
The replacement tcon is for this screen size, the TT-55"43"xxx part states, that both are for this 43 inch screen.

(Talking of which - I often repair VGAs and even laptops by changing the GPU/CPUs to whatever compatible I have laying around.. like, yesterday I put a 2070 GPU core on a 2060s PCB, since that was the only one I had laying around, flashed the right BIOS, and it works..
Also, I test laptop LCDs with whatever compatible (lvds/edp) based laptop I have laying around.. I can test whatever sized lcd, as long as the connector is compatible.

How come we still don't have universal LVDS cables for TVs? For instance, let's say, the mainboard in this TV is good, but the screen is not.
Then I have another TV outside, where the screen and tcon is perfect, but the mainboard is not (the customer popcorned the QFU chip before he gave the tv to me). I don't see the point to make the TCON LVDS pinout different, when the screen is the same size, resolution is also the same, voltage, etc.. or is there something like this?)

There's prolly more profit working with pcs than tvs in most places for sure. There are some awesome tools out there, saw a small universal screen being used in a repair video the other day, wouldn't mind having one of those.