Sony xbr-75x900f 6 red blink

[EazyBone]

Picked up a $4000 2018 TV and it's blinking 6x red. A search says something with backlights or led drivers board. This is my first time with such a complex TV. It's got 2 power boards, led drivers, tcon, main it's crazy lol.

So I check voltages to main, all fine. 12.47v. I hit power and the BL_ON goes to 3.5V shortly and will kick off and red light flashes. Power board looks to be okay, but there is 2 power boards lol. 12V is at least hitting the second power board.

I'm gonna test everything but how do I even test the LEDs on this thing without taking it all apart? Usually it's a wire going to lights, this has 12 ribbons. Can led tester show me if these work? Any help would be appreciated.

[nomoresonys]

Re: Sony xbr-75x900f 6 red blink

Check the bl_error pin, cn6401 pin 1.

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

Check the bl_error pin, cn6401 pin 1.

Am I looking for any voltage?

Turn on TV. Voltage 3.3. Power board relay clicks drops to zero get flashing red light. The LED driver board has an LED that turns on

[Storyteller12]

Re: Sony xbr-75x900f 6 red blink

6 blinks on Sony TVs is bad backlights. Have to take it apart and replace them

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

6 blinks on Sony TVs is bad backlights. Have to take it apart and replace them

This needs a diagram just to take it apart. Good Lord.

[lotas]

Re: Sony xbr-75x900f 6 red blink

SONY XBR-75X9*F GN4TR CHASSIS "6" - error.

[Storyteller12]

Re: Sony xbr-75x900f 6 red blink

This needs a diagram just to take it apart. Good Lord.

Yeah, Sonys are never fun to tear apart. Not hard, just time consuming and tedious.

Good luck. Let us know how it goes

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

Yeah, Sonys are never fun to tear apart. Not hard, just time consuming and tedious.

Good luck. Let us know how it goes

I've torn apart quite a few. I'm considering replacing a single LED or all of them.. all is $110 though. Although the 75s are very worrisome when taking the screen off. I did it 3x and no break yet but man it don't feel stable.

I read in another post some guy tried a single LED on these sonys and it wouldn't accept it.. so probably gonna go new route. But will report fix when it happens

[nomoresonys]

Re: Sony xbr-75x900f 6 red blink

There's a test that sometimes works, involves grounding the bl_sos wire, of course I forgot exactly how it's done, check Nick's tv on youtube, he has at least one video of the test "temp fix"

[nomoresonys]

Re: Sony xbr-75x900f 6 red blink

One there, probably more too: https://www.youtube.com/watch?v=T3VRvQUB_DQ

[Storyteller12]

Re: Sony xbr-75x900f 6 red blink

You can replace single led. All the xbr series I’ve worked on are 12v though. Not 3v or 6v like most. Not a common voltage and sometimes harder to find. But it can be done.

[Davi.p]

Re: Sony xbr-75x900f 6 red blink

I suspect in this type of set leds hardly can fail, the smaller power board is the led power board, i see it takes pfc tension from main psb and transforms it with the big transformer to i guess a smaller tension, check first in the early seconds of tv on the output voltage of that board, check it also on the blue board after the fuse, on that there is i guess also a micro controller, the software on it can be failed also, getting apart so a big tv for testing leds is high risky, all tests on boards are mandatory before.. get the service manual!

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

You can replace single led. All the xbr series I've worked on are 12v though. Not 3v or 6v like most. Not a common voltage and sometimes harder to find. But it can be done.

Would this be the set you are talking about? I can only find one type for 12v. Is there different ones? Would rather replace one then all.

Just found this amazing item on AliExpress. Check it out! $9.56 | 50PCS For SONY LED LCD Backlight TV Application LED Backlight 2.5W 12V 3535 Cool white TV Application
https://a.aliexpress.com/_mPFT8IE

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

I suspect in this type of set leds hardly can fail, the smaller power board is the led power board, i see it takes pfc tension from main psb and transforms it with the big transformer to i guess a smaller tension, check first in the early seconds of tv on the output voltage of that board, check it also on the blue board after the fuse, on that there is i guess also a micro controller, the software on it can be failed also, getting apart so a big tv for testing leds is high risky, all tests on boards are mandatory before.. get the service manual!

I can do that, but at what test points? Sorry this additional board is confusing to me. I'm self learning all of this (with this group and internet). Am I looking for voltages coming from main PSU to the LED PSU? There is 2 sets of wires going to it. Or the voltages coming from LED PSU to the LED driver board? Sorry for all the questions.. but I'll try and mess with all voltages I see.

OR I'm gonna Google a service manual, but maybe you know a site to get them fro

[Davi.p]

Re: Sony xbr-75x900f 6 red blink

the output voltage of the led psu.. photograph also close the ARM cpu on the blue board..

[nomoresonys]

Re: Sony xbr-75x900f 6 red blink

Well did you watch Nick's video linked in post #10.

[Storyteller12]

Re: Sony xbr-75x900f 6 red blink

Would this be the set you are talking about? I can only find one type for 12v. Is there different ones? Would rather replace one then all.

Just found this amazing item on AliExpress. Check it out! $9.56 | 50PCS For SONY LED LCD Backlight TV Application LED Backlight 2.5W 12V 3535 Cool white TV Application
https://a.aliexpress.com/_mPFT8IE

Those should work. But I would take it apart and remove the bad led just to verify there the same.

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

Well did you watch Nick's video linked in post #10.

Yes actually and when I grounded it from LED driver PSU to main PSU I got it then to blink 4x. When I did main PSU to LED PSU It stayed 6 blink.

I cannot also get a voltage on the LED driver at the fuse at all. I do get a yellow light on the driver that lights up temporarily and a red one that flashes 3x stops then 3x occasionally

[EazyBone]

Re: Sony xbr-75x900f 6 red blink

Here's blue board pics

[Davi.p]

Re: Sony xbr-75x900f 6 red blink

Repeat... check the led psu output in the early seconds after power up...
the STM32 cpu can be programmed with a big free software from ST website and a cheap i2c adapter or a ch341a (don't remember), but it's quite hard and is also hard find firmware.. the power on the blue board must be checked in early seconds!!