Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is present

[SkishyIshy]

Hey All,

I have a Sony 65x900f that I purchased cheap because of a no-power issue.
I assumed that because there is no standby light visible, it would be an easy fix - however upon opening up of the unit I can confirm that the 3v3 standby voltage is making it's way from the power supply to the main board. I'm a little confused as to why there is no standby light.

I am firstly wondering if anyone has this model of TV, or has worked on one and can give me some insight. I have tried to find a service manual for this model, to no avail - and would really appreciate some help with any of the following:

- When the TV is plugged in, does it automatically power on, or is it waiting for the press of a button/remote?

- When the TV is in standby, is a standbylight illuminated, and if so - where is it located?

- When the power button is pressed, does it power the TV upon the press or the release of the button?

- When the power button is pressed, how does the voltage behave on the "power_on" pin of the power supply?


I can confirm that the the power_on pin of the PS has 3.3V across it upon initial plugging in of the TV. When the power button is pressed, power_on drops by about 10mV... seems pretty negligible to me, but I am unsure of what it is expecting. Is this normal?

I don't seem to be getting power on signals to the LED driver board, or to the TCON board, but the transformers/rectifiers on the power supply are all doing their jobs and are supplying the correct voltages at their outputs - they just aren't getting routed to the proper pins. (ie. 12V is present on the LD board, but LED_VCC are all at 0 V)

I assume that the problem has to do with switching the power pins for the TCON/LD board etc, but am not certain if what the main board is sending to the power supply is faulty, or if there is simply a problem with a switching element on the power supply board itself.

I am hoping to fix this at the component level, but with zero documentation/service manuals available for the x900f, I am essentially trying to reverse-engineer it. I figured I might as well reach out to see if anyone else has had experience with this model and can give me some insight.

Any help is appreciated!
Thanks

[dick_barton]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

Can you post photos of the legend along side the two connectors and also what voltages do you have on those connectors?
Connector xxx
Pin 1 Name Volts
Pin2 Name Volts
Etc

[R_J]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

You can't go by the led on the front, on some TV's (some Sony's) the led comes on to indicate the tv is ON. and the led is OFF in standby.
CN6401 has two rows of pins, make sure you are checking the correct pin for POWER_ON (it's pin9) so you can't access it from the top of the board.
Since you have STBY 3.3v I suspect the problem is on the main board.

[SkishyIshy]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

LD Board Connector
CN6601
Pin 01 "12V(LD)": 12.74V
Pin 02 - N/C
Pin 03 "GL_CTRL": 0.001V
Pin 04 "SENSE_GND": 0.001V
Pin 05 "VLED_GND": 0.001V
Pin 06 "VLED_GND": 0.001V
Pin 07 "VLED_GND": 0.001V
Pin 08 "VLED_GND": 0.001V
Pin 09 - N/C
Pin 10 "VLED_VCC": N/C
Pin 11 "VLED_VCC": 0.001V
Pin 12 "VLED_VCC": 0.001V
Pin 13 "VLED_VCC": 0.001V
Pin 14 "VLED_VCC": 0.001V

Main Board Connector
CN6401
Pin 01 "BL_ERR": 0.036V
Pin 02 "BL_ON": 0.002V
Pin 03 "POWER_ON": 3.472V
Pin 04 "GND": N/C
Pin 05 "STBY 3.3V": 3.505V
Pin 06 "GND": N/C
Pin 07 "GND": 0.001V
Pin 08 "GND": 0.001V
Pin 09 "REG 12V": N/C
Pin 10 "REG 12V": 12.75V
Pin 11 "REG 12V": 12.75V
Pin 12 "REG 12V": N/C
Pin 13 "REG 12V": 12.75V
Pin 14 "REG 12V": 12.75V
Pin 15 "REG 12V": 12.75V
Pin 16 "REG 12V": 12.75V
Pin 17 "GND": 0.001V
Pin 18 "GND": 0.001V
Pin 19 "GND":0.001V
Pin 20 "GND": 0.001V
Pin 21 "GND(TCON)": N/C
Pin 22 "GND(TCON)": 0.001V
Pin 23 "GND(TCON)": 0.001V
Pin 24 "GND": 0.000V
Pin 25 "TCON_VCC12V": N/C
Pin 26 "TCON_ON": 0.001V
Pin 27 "TCON_VCC12V": -0.001V
Pin 28 "TCON_VCC12V": -0.001V



Good to know about the absence of standby light on some Sony's because having standby voltage with no indicator was really causing me to scratch my head.

I was originally thinking a problem with the main board, but ~3.5V at power_on pin leads me to be skeptical... Should this voltage change with the press of the power switch? It does not.

I did notice that when I set my multimeter to measure AC voltage with chassis GND connected to the multimeter common, and the positive lead floating, ~2.7VAC was registering on my multimeter.

[nomoresonys]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

"Pin 02 "BL_ON": 0.002V" way too low, that signal comes from the mainboard, looks like mainboard issue.

[nomoresonys]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

Try unhook cable from powerboard to mainboard, leave it out, plug power cord into powerboard and take those readings again.

[budm]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

"Pin 26 "TCON_ON": 0.001V
Pin 27 "TCON_VCC12V": -0.001V
Pin 28 "TCON_VCC12V": -0.001V"

T-CON ON also missing, something is stopping the main board from sending the control signals.
What is the history of the TV?

[SkishyIshy]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

Try unhook cable from powerboard to mainboard, leave it out, plug power cord into powerboard and take those readings again.

When I did this the other day I'm pretty sure the only two pins that changed were:

CN6601
Pin 01 "12V(LD)": OV

and

CN6401
Pin 03 "POWER_ON": 0V

I will confirm later this evening.

[SkishyIshy]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

"Pin 26 "TCON_ON": 0.001V
Pin 27 "TCON_VCC12V": -0.001V
Pin 28 "TCON_VCC12V": -0.001V"

T-CON ON also missing, something is stopping the main board from sending the control signals.
What is the history of the TV?

Previous owner claims that he moved the TV from his old house to his new house in the OG box (horizontally.. with nothing on top of it) and it worked fine for about a week. One night he turned it off before bed and then it never turned on again.

[William1967]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

Looks like a EMMC problem, it's very common with Sony mainboards.

[SkishyIshy]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

Try unhook cable from powerboard to mainboard, leave it out, plug power cord into powerboard and take those readings again.

My bad, turns out everything except the STBY3.3V pin registers as ~0V when the cable from the PS to mainboard is disconnected.

Standby still shows as ~3.5V

[nomoresonys]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

I think I would test the powerboard and backlights, unplug cable from mainboard to powerboard on powerboard side, leave it UNPLUGGED, use about a 1k resistor and jump STBY3.3 to POWER_ON and another 1k resistor to jump BL_ON to STBY3.3, plug power cord into powerboard, see if your backlights come on and the same voltages you checked are steady.

[SkishyIshy]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

I think I would test the powerboard and backlights, unplug cable from mainboard to powerboard on powerboard side, leave it UNPLUGGED, use about a 1k resistor and jump STBY3.3 to POWER_ON and another 1k resistor to jump BL_ON to STBY3.3, plug power cord into powerboard, see if your backlights come on and the same voltages you checked are steady.

When I jump BL_ON and POWER_ON to standby nlthe backlight does NOT turn on (as far as I can tell. Still a lot of daylight in the house)...

Pins with different voltages compared to most nea previously are as follows:
LD Board Connector
CN6601
Pin 01 "12V(LD)":12.75V
Pin 02 - N/C
Pin 03 "GL_CTRL":
Pin 04 "SENSE_GND":
Pin 05 "VLED_GND":
Pin 06 "VLED_GND":
Pin 07 "VLED_GND":
Pin 08 "VLED_GND":
Pin 09 N/C
Pin 10 "VLED_VCC": N/C
Pin 11 "VLED_VCC": 25.72V
Pin 12 "VLED_VCC": 25.72V
Pin 13 "VLED_VCC": 25.72V
Pin 14 "VLED_VCC": 25.72V

Main Board Connector
CN6401
Pin 01 "BL_ERR": 0.002V
Pin 02 "BL_ON": 3.435V
Pin 03 "POWER_ON": 3.507V
Pin 04 "GND": N/C
Pin 05 "STBY 3.3V": 3.507V
Pin 06 "GND": N/C
Pin 07 "GND":
Pin 08 "GND":
Pin 09 "REG 12V": N/C
Pin 10 "REG 12V":
Pin 11 "REG 12V":
Pin 12 "REG 12V": N/C
Pin 13 "REG 12V":
Pin 14 "REG 12V":
Pin 15 "REG 12V": (these are all on at 12.75)
Pin 16 "REG 12V":
Pin 17 "GND":
Pin 18 "GND":
Pin 19 "GND":
Pin 20 "GND":
Pin 21 "GND(TCON)": N/C
Pin 22 "GND(TCON)":
Pin 23 "GND(TCON)":
Pin 24 "GND":
Pin 25 "TCON_VCC12V": N/C
Pin 26 "TCON_ON":
Pin 27 "TCON_VCC12V":
Pin 28 "TCON_VCC12V":

All ground pins are continuous

[R_J]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

The BL_ON only turns on the SUPPLY VOLTAGE to the backlight driver board, The main board drives the backlights with data not just an on or off command. The fault is likely on the main board and could be a BGA problem or a firmware problem.

[SkishyIshy]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

Ah dangit - that's definitely what I was afraid of!
Super helpful info though, thanks.

I COULD dust off the old BGA rework station for this, but I might just take the easy way out and buy a new main board...

Thanks everybody for all your help!

[thekidtmac73]

Re: Sony Bravia XBR-65x900f: No Power, No Standby-light - however 3.3v STBY is presen

I have a Sony XBR 55 x800e are the pins on a power board the same as above?

Thank you