Sony 75X9400E TV.. 5 Red blinks

[dumbdd]

I was using this TV for 5 years before it stopped working. I like this TV and would love to fix it myself.*

When I press the power button, the white led comes on (sony calls the module smart core) and then it switches over to 5 red blinks. No screen, no backlight, no relay click, nothing. I have disassembled the tv and found the service manual for 75x940e online. The manual suggests a faulty power board, TCON or the panel.**

The standby pin is at 3.3V. Fuses on the mainboard and TCON are fine. Caps on TCON also seem to be fine. When I turn on the tv the white led comes on and REG_12V pin on power board measures 12.8V, VDDB_3.3V pad on TCON measures 0.577V. When it switches over to 5 blinking reds, the voltage on REG_12V and VDDB drops to 0.**

I also disconnected the power board and shorted standby pin to POWER_ON and TCON_ON. Both measure 12.8V. Power board seems to be fine.

I disconnected the ribbons going out of TCON to the buffers and then turned on the tv. I still get 5 blinks.

What should I do next to narrow down the problem, any advice is welcome. Thanks!

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

Some updates, tcon is supposed to get it's power directly from the power board through a dedicated connector (obvious in the pics) . TCON_ON is not being shorted to STBY_3.3V by the main board during boot up. I disconnected the power cable to the main board and jumpered STBY_3.3V to TCON_ON. TCON started getting 12.8V and VDD_3.3V on the tcon was stable at 3.3V. Leads me to believe that the problem might be with the mainboard.
I'm at a complete loss here guys, what should I do next?

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

I don’t have a suggestion for you, but my Sony A1E has an almost identical failure.
5-blinks indicating a T-Con communication failure and TCON_ON not being asserted.
My plan next was to try look at UART and I2C communication between the main processor (BKA) and the upscaler (DKA).

Also trying to locate a replacement BKA board for a reasonable price given that I don’t 100% know that’s the source of the fault.

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

I tried to scope out the I2C and UART between the Main Board (BKA) and the Upscaler (DKA) and couldn’t work out what’s wrong with my system. Without a known good system or more logs to pin point a specific failure area I’m at a loss to figure next steps also.

I’m hoping I can find a working Main Board for a reasonable cost, since I don’t know for sure that’s even the issue.

Did you get any further in your debug?

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

Hey. Replaced the T-con, didn't make any difference.. Still getting 5 blinks just like you. In my case the soc and upscaler are on the same board (BMKP). I have pretty much arrived at the your conclusion, the bmkp is not turning on the power to the T-con.

I plugged a usb into one of the ports on the tv and then looked at the files on a pc, the tv had created a couple of standard Android related folders.. seems like soc is working fine. Could still be emmc corruption or some other faulty chip on the mainboard.

My tv is 75x9400e which is a European model. I couldn't find a credible source for a replacement mainboard for this specific trim. Found a cheap used 55x930e replacement board on ebay, the seller says the board is working fine and the problem is the physical damage to his panel (sent me pics to confirm). Visually the boards are identical, I'm guessing I'll end up getting the green amber blink with the new board but at least there will be some progress. Will probably need to do a usb firmware update or emmc swap from the old board.

I will have more updates when I get the healthy mainboard. I'm in Dubai, it takes a week or so for the shipments from US to get here. I'll keep this thread updated.

For your tv, is it the BKA or the DKA that asserts the tcon_on pins on the psu?

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

You were able to see the Android file system of your TV when it boots to 5-blinks?
You plugged into the USB shown here into your laptop?
https://i.rtings.com/assets/products...back-large.jpg

What does amber green amber blink represent?
Why do you think you’ll hit this next?

Yes on my TV the DKA assets the TCON_ON pin into the PSU.
But I’ve already replaced the DKA, so I’m now suspecting the main board (DKA) isn’t giving the right commands to the DKA. But that’s pure speculation.

I’d love to hear your results when you get your replacement BMKP.

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

I was trying to update the tv to the latest firmware to rule out any previous botched update I guess. So I copied the latest pkg file for my tv into the root of the thumb drive and plugged it into the top most port (USB 1) on the tv.
https://i.rtings.com/assets/products...side-large.jpg


Then I turned on the power and there was some activity on the thumb drive led (also means REG_12V was up at this point). Turned on the tv and REG_12V dropped to zero, led activity on the thumb drive stopped and tv started doing it's 5 blink thing. Then I plugged the thumb drive into my laptop and there were some extra empty folders that the tv had created apparently (folder names Android and LOST.DIR). Makes me think the soc, BKA in your case, is probably working.

Amber green blink means a mainboard/tcon/panel mismatch. The boards need to be paired again.
https://www.youtube.com/watch?v=3kYPjIHt8Lc&t=308s

It is interesting that the upscaler is controlling the tcon_on pin, I was suspecting the mainboard to be responsible for controlling power delivery to various sections of the tv.

Do you have any photos of the mediatek processor and the upscaler without the heatsinks? If the processors are similar in both the tvs, I wanted to check the resistance on a couple of caps around these processors.

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

Thanks for the pointer about re-pairing, I wasn't aware that was needed.
Here's a picture of my Mainboard (BKA).
It's maybe not surprising that our boards look pretty similar.

Let me know which resistances you want measured.

I went through quickly making sure no caps was shorted and that all the power supplies were the voltages called out in the service manual.

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

I think I might have found the issue in my case. C4602 and C4802 caps are giving me 5 ohm resistance. Probably means the upscaler chip is dead? Can you please check these cap resistances for me, I went through your board schematics and our boards are pretty much the same, even down to cap labels.

Did you try the usb firmware update to get an idea if your BKA is working?

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

I have two upscaler boards (DKA).

The first DKA came out of my TV and draws a lot of current somewhere downstream of the 3.3V supply.

I bought a replacement DKA that came out of a TV w/ a cracked display.

On this replacement DKA board both the caps you highlighted measure 4.5 ohms to ground.

Yes, on my TV when powering up the mainboard (BKA) it does generate some files to the USB stick.

./LOST.DIR
./Android
./Android/data
./Android/data/.nomedia
./Android/data/com.google.android.music
./Android/data/com.google.android.music/files
./Android/data/com.google.android.music/files/._playmusicid
./Android/data/com.google.android.gms
./Android/data/com.google.android.gms/files

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

I think 4.5-5 ohms is a bit too low on those pins but then we both got the same value so I don't know. Not much we can do here until my replacement board gets here I guess.

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

I got the replacement mainboard from 55x930e yesterday. With the replacement board installed, the tv tries to start (white led turns on and off multiple times for a minute or so) but ends up giving 8 red blinks. BMKP is the same for 55 and 75 inch models but the power boards are quite different. Some pins on the power header in 55" schematics are not connected or connected differently if we compare them to 75" schematics. I'm guessing I need to transfer the emmc from my old board to the donor board, that's pretty much the only thing left to do. Any other ideas?

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

My tv is fixed! Replaced the emmc on the original board and it started working (had to do the pairing).

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

Congratulations!

Just so I'm clear:
Your TV was a 75x9400e (75" Euro model).
You bought a replacement mother board for a 55x930e (55" US model).
After the board swap you saw 8-blinks which is 4K BE (upscaler?) error.

You un-soldered the eMMC from your original motherboard and moved it onto the replacement motherboard and now it's working again?

That's pretty impressive!
Mind if I ask how you did the eMMC swap?
Just hot air re-work station or was it more involved?

[dumbdd]

Re: Sony 75X9400E TV.. 5 Red blinks

Yes my TV was EU 75x9400e. Replacement board belonged to a US 55x930e but it turned out this board was faulty (it was used from ebay) but had a functioning emmc. The replacement board gave me 8 red blinks, in general it means the mainboard is faulty. I almost gave up on the repair because t was getting frustrating and the tv was taking space in my bedroom. Nick has a lot of vids on youtube for different sony models and I have noticed most of times it's the emmc that craps out. So I decided to try one last thing, took both the boards to a mobile repair shop and told the guy to swap the emmcs on the boards (cost me like 25$ here in dubai, took 20 min). I have a rework station but I don't trust my bga soldering skills. Hot air gun to remove the chips, cleaned the pads on the board and the chips with a solder wick, reballed the chips using a stencil and then hot air to mount the chips on the boards.

New board with old emmc gave me 5 blinks again. I am guessing the new board is probably faulty (it threw 8 blinks with it's own emmc).

Old board with 55x930e emmc gave me green/amber blinks which means it just needs to be paired with the tcon. I did a hard reset on the tv (hold power and vol down and plug in the tv). The light turned green, showing the tv was resetting. Then it restarted and started flashing green/amber again, there were relay clicks for the first time, I was happy. I could hear android tv initial setup music at this stage, but no picture. Downloaded the latest firmware for US 75x940e (it is the same file for 55x930e), put it on the usb root and force upgraded the firmware. This step took a lot of trial and error. I tried renaming the file to upgrade_loader.pkg, I tried fat32/ntfs, different flash drives, different usb ports. In the end the combination that worked for me was a 32gb samsung flash drive with ntfs, original firmware filename (sony_dtv0FA60A0AA0AA_00004300_16072151000364.pkg) in usb port labeled USB 2. I had restarted the tv with the usb plugged in, I could hear the android music, amber/green blinks, no picture, I left it like this for a couple of minutes and then the light switched to blinking white (which means firmware is upgrading), it took 15/20 min for the upgrade, tv restarted a couple of times and then eventually the screen turned on and the android setup screen showed up. Don't give up at this stage, it's a lot of trial and error.

TV is working fine. It thought it was a 55x930e but I switched it to 75x940e through the service menu after setting up the tv, I think it's only cosmetic.. didn't seem to make any functional difference. I don't know how to flash the emmc to the EU region, once again it's just cosmetic there's no difference as such. Oh and anything that needs widevine or drm (netflix, amazon prime) doesn't work because I think the emmc is not paried to the soc? It doesn't matter to me, the tv OS was always slow and clunky and I was using nvidia shield anyways and that works just fine.

Regarding your tv, see if you can find a replacement emmc or a BKA. Also don't discount the fact a lot of these replacement parts are also faulty in one way or the other. After fixing the tv, just for curiosity I swapped the tv's tcon with the one I bought from tvpartstoday. With this tcon the right half of the tv is darker and has artifacts. So both the tcon and the mainboard that I had bought from 2 separate sources were faulty.

Anyways, I'm around if you need any help with your tv.

[jchon]

Re: Sony 75X9400E TV.. 5 Red blinks

That's really helpful knowledge.

I didn't think that eMMC corruption alone would generate 5-blinks, but your process says otherwise. Let me see if I can track down a pre-flashed eMMC for my model while I keep looking for a reasonably priced motherboard replacement.