Sony Bravia XBR-55X850B - three blinks

[jimanez11]

Hey guys.

So I have a Sony XBR-55X850B that was recently given to me that fell victim to a lightening storm. At first when the TV is plugged in, it immediately attempts to power up, but instead the front LED only blinks three times. Based off of some google searches, I think the three blinks represents either a bad power supply board or a bad main board. I tried testing the Reg12V output from the power supply to the main-board, but didnt get any readings on my multimeter. Went ahead and replaced the power supply board with one from Amazon that was pulled from a TV with a busted screen. Once hooked up, still the same result. Power the unit on and three red LED blinks and nothing else and no power reading from the REG12 port on the output to the main board. Can anyone verify whether the three blinks on this model TV points to a bad PSU/Mainboard, and, if so, what the next steps are?

Thanks!

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

First step is to show us good clear pictures of the whole back side of the TV so we can see the board.
Then we need DCV reading of the connector of the power supply board that goes to the main board, we need the pin names and pin number of each pin.
Take the reading when the TV is plugged in but not turned ON, then the reading after the power switch is activated. We need to know what Voltages and what command signals are there or not there.

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

Thanks for the quick response! It is appreciated.

The pictures of the back of the TV, along with the PSU and the Mainboard are attached.

The pin numbers and names are included in a close-up of the port on the PSU, but also outlined below with a note of their voltages when the TV is plugged in.

# Name Voltage (DC)
1- NC - No Pin
2- DIGITAL_STBY - Varies between 100mv – 205mv – not constant
3- BL_ERR - 0v
4- NC - No Pin
5- BL_ON - 0v
6- GND - 0v
7- GND - 0v
8- GND - 0v
9- GND - 0v
10- GND - 0v
11- GND - 0v
12- REG12V - ~2mv
13- REG12V - ~2mv
14- REG12V - ~2mv
15- REG12V - ~2mv
16- REG12V - ~2mv
17- REG12V - ~2mv
18- T-CON_VCC12V - 0v
19- T-CON_VCC12V - 0v
20- T-CON_VCC12V - No Pin
21- T-CON_VCC12V - 0v
22- TCON_GND - 0v
23- TCON_GND - 0v
24- STBY_GND - No Pin
25- STBY_3.3V - 3.467v
26- T-CON_ON - 0v
27- AC_OFF_DET - 3.465v
28- POWER_ON - 0v

I am not able to turn the TV on and when the power switch is pressed, none of the voltages change. There is an audible click when the TV is plugged in, then about 7 or 8 seconds later, another click then the three flashes from the front LED.
Based on the 3.3v standby being there, does this point to an issue on the mainboard?

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

OK, I cannot find the service manual for this model to verify the blinking code, but from looking at the list of the DCV readings, the main board is not sending the POWER_ON to turn on the power supply.
No T-CON on command to turn on the T-CON 12V power supply, no BL_ON to turn on the backlights circuit.
These Voltage readings were taken after the power switch is activated, right?

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

The readings were taken when the TV was plugged in. Nothing happens when I hit the power switch on the back of the TV, but if I am quick with the multimeter probes, I get a few mv's from both BL_ON (roughly 4mv) and then roughly 2mv on TCON-ON. Both of these values quickly go to zero after the second audible click followed by the three flashing lights on the front LED. When looking at the screen and hitting the power button / plugging it in, the TV doesn't even flash like the backlights are being turned on though.

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

You need to leave the probe on the Power_on pin to see if it jumps up to >2.5VDC when you hear the power relay click and then drops down, it sounds like the POWER_ON signal was present then goes away.
It is may be sensing the fault some where so the POWER_ON is cut off.

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

It looks like this problem has been around for a long time even with a new set, sounds like a lemon set.
https://community.sony.com/t5/4K-Ult...es/td-p/471861

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

Left the probe on the POWER_ON pin when plugging it in and when pressing the "Power" button on the back of the TV with no result, voltage stayed at 0v. So does this mean that the TV is getting the error before it even enters the start-up process? The mainboard isn't giving the "OK" back to the power-supply to send over the 12v from the other pins that allow the rest of the MainBoard to power on?

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

It looks like this problem has been around for a long time even with a new set, sounds like a lemon set.
https://community.sony.com/t5/4K-Ult...es/td-p/471861

I read those posts as well and they all ended up getting their sets replaced under warranty. The only difference I could tell was that this one happened to die during a lightening storm. You think it may be a coincidence that the timing seemed to match? or maybe the power surge just exacerbated the problem?

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

That means the main board is locked out and not even allowing the main board to send the turn on commands to the power supply board. I do not know what is causing the problem at this point, may have to start disconnecting board one at a time to see if it will allow the TV to be turned on.
I did the search and found that a lot of people have this 3-blink error even on a new set, see post 7.

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

Cool. Was hoping for an easy fix, but the TV was free on CraigsList so hey, why not. At the moment, do you think there is any benefit to even try replacing the mainboard? In the mean-time, I will try to go through and disconnect the other boards one at a time to see if that fixes anything.

Thanks for the help with this so far, and if you come up with any other ideas about potential next steps, please let me know.

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

https://www.badcaps.net/forum/attach...5&d=1465843674
Try disconnect that small green board with 3 white connectors at the bottom left corner of the main board to see what happen.

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

So all boards have been disconnected and cables have been reseated and, as a result, I am now getting 3.44v to the POWER_ON pin on the main PSU output right when the TV is plugged in to the wall but nothing happens when I hit the power button on the back of the TV. This went on for about 5 or 6 restarts (unplugs then plugging back in) and then after that, no more 3.44v. I probably should have done this the first time, but I will disconnect each cable from the mainboard and test disconnected and then reseated. Hopefully something good will come of this, but the initial 3.44v on POWER_ON is a step in the right direction.

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

I wonder if you should try new firmware that just came out last month.
https://esupport.sony.com/US/p/model...d#/downloadTab

[Diah]

Re: Sony Bravia XBR-55X850B - three blinks

you have power_ON signal from the main boards,,, other wise if you dont have it you will not seen the LED blinking.

diagnose from budm correct, there are block to the voltage od 12 DC, which it caused 1 power boards dont supply it, or the sound driver, which request to plug it out.. or also the RF B Boards, you can also disconnected from main boards, and power on..

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

Everything has been reseated and all boards have been disconnected and reconnected, with no 3.44v anymore. There is an interesting update though, when I plug in the TV and then immediately press the power button, the set will now turn on. The only thing that is shows is two arrows forming a circle and rotating. This goes on for about 10 seconds, then the set will shut off. Any idea what this could be, or what could have caused such a stark change in how the power button reacts?

Also, I have tried this both with the audio driver board plugged in to the main board and also removed from the main board, with the same result.

[budm]

Re: Sony Bravia XBR-55X850B - three blinks

https://community.sony.co.uk/t5/tele...e/td-p/1966203

I would try new firmware or wait to see what will happen since it can take very long time for the firmware to be updated.

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

Thanks BUDM, I have tried to let it run its course as if it were an update, but the set just shuts off after about 15 - 20 seconds of getting to this point and then it wont restart, have to unplug and then plug back in and hit the power button to get it back up again. Also, it turns on right in to this spinning circle, no SONY logo or anything. I am trying to find boot-up / update videos on youtube to compare the arrows I see on the screen. Will keep you updated!

Thank you both for your help so far!

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

Installed the most recent firmware update to a USB device and have it plugged in to the TV. The set has been updating for the past 1.5 hours. Will update either when complete or at some point tomorrow morning when I have given up on the update.

[jimanez11]

Re: Sony Bravia XBR-55X850B - three blinks

So the update appears to be a no-go. Woke up this morning after giving the TV about 11 hours to complete the update and the circle was still spinning on the set. Is there any way to do a hard reset on the TV and potentially roll back a previously corrupt update install? I have tried the "Factory Reset" command of holding the up button on the remote while holding the power button down on the back of the set, but nothing happened. Also, the front LED is now a blueish / purple color.