Sony 40EX400 Dead Power supply reads good

[coreyand]

Ive got a Sony 40EX400 That I get good reading from the power supply heres the list of what I get


This is from CN6402 going to the inverter board. Im counting the pins 1-14 from top to bottom.

Pin 1 - 25.7vdc This is labeled as 24v
Pin 2 - 25.7vdc This is labeled as 24v
Pin 3 - 25.7vdc This is labeled as 24v
Pin 4 - 25.7vdc This is labeled as 24v
Pin 5 - 25.7vdc This is labeled as 24v
Pin 6 - 0 This is labeled as Ground
Pin 7 - 0 This is labeled as Ground
Pin 8 - 0 This is labeled as Ground
Pin 9 - 0 This is labeled as Ground
Pin 10 - 0 This is labeled as Ground
Pin 11 - 3.292vdc This is labeled as BL_ERR
Pin 12 - 3.9 mVdv This is labeled as BL_ON
Pin 13 - Theres no wire here. Labeled as NC(ADIM)
Pin 14 - 4.0 mVdc This is labeled as Dimmer.

On the other connector going to the main board labeled CN6401 once again labeled 1-14 from top to bottom is

Pin 1 - 0 This is labeled as TCON ON
Pin 2 - 0 This is labeled as TCON VCC - 12V
Pin 3 - NC
Pin 4 - 4.1 mVdc This is labeled as Dimmer
Pin 5 - 4.0 mVdc This labeled as BL_ON
Pin 6 - 3.293 Vdc This is labeled as BL_ERR
Pin 7 - 12.71vdc This is labeled as REG12V
Pin 8 - 12.70vdc This is labeled as REG12V
Pin 9 - 0 This is labeled as REG12V GND
Pin 10 - 0 This is labeled as REG12V GND
Pin 11 - 0 This is labeled as AU12VGND
Pin 12 - 12.71vdc This is labeled as AU12V
Pin 13 - 3.74vdc This is labeled as POWER ON
Pin 14 - 2.712vdc This is labeled as ACOFFDET
Pin 15 - 3.299vdc This is labeled as STBY3.3V


I checked the voltage that is outputted from the main board to the key pad to make sure the power button was getting the P_ON and 2 out of the 4 pin connectors read 3.29vdc. This is on CN950 of the main board.

Another thing to note, normally when you plug just about any tv into power you hear 1 or 2 relays click once or twice. When I plug this one in I hear no relays click.

SOOO I have good voltage to the components, the inverter and the main board. Does this mean possibly the mainboard is bad? Or am I still looking at the power board with no clicking.

Furthermore do the boards always output this high of voltage without being switched on?

Another thing to note is when I got this tv the power cable inside had come loose from the pin connector on the power board and looks as if they were arcing out all over the place and I had to replace the fuse marked F6101 and underneath the board there places the the conductor metal in the board that were basically blown away, so I took some solder and bridged where conductive part of the board was gone.

So am I looking at getting a new main board or do you guys think there will be more underlying issues with the power supply because the relays dont click when you power it on or plug it in?

Thanks guys I really need your help on this one im stumped.

[CapLeaker]

Re: Sony 40EX400 Dead Power supply reads good

What is the TV doing or not doing? Can you turn it on/off? Is there a STBY LED on? Got back light, etc?

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

Doesnt power on, no standby light, no backlight. It acts as if its unplugged from power, does nothing.

[budm]

Re: Sony 40EX400 Dead Power supply reads good

"Pin 11 - 3.292vdc This is labeled as BL_ERR
Pin 12 - 3.9 mVdv This is labeled as BL_ON
Pin 13 - Theres no wire here. Labeled as NC(ADIM)
Pin 14 - 4.0 mVdc This is labeled as Dimmer."

The board is not getting the backlights ON command, and no backlights Dimmer control signals from the main board.
One thing I am not sure is the BL-ERR (BACKLIGHTS ERROR) is normally HIGH (>2.5VDC) or normally LOW, this may be why the backlights command is not present, need to look at the service manual to verify.
You do not see front panel blink codes?

[CapLeaker]

Re: Sony 40EX400 Dead Power supply reads good

Doesnt power on, no standby light, no backlight. It acts as if its unplugged from power, does nothing.

So how did you turn it on to get these measurements?

[budm]

Re: Sony 40EX400 Dead Power supply reads good

So how did you turn it on to get these measurements?

He has POWER ON SIGNAL:
"Pin 13 - 3.74vdc This is labeled as POWER ON"

[CapLeaker]

Re: Sony 40EX400 Dead Power supply reads good

He has POWER ON SIGNAL:
"Pin 13 - 3.74vdc This is labeled as POWER ON"

In post 3 he sez it's dead, does nothing. I saw that PSon has power too That's why I asked for the STNBY LED in post 2.

[budm]

Re: Sony 40EX400 Dead Power supply reads good

It looks to be he has the problem with the main board at this point, the PS-ON is stuck on.
I need to locate the service manual for this chassis.

[budm]

Re: Sony 40EX400 Dead Power supply reads good

There are many threads about this model that OP should read through them.
https://www.badcaps.net/forum/search...archid=4486138

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

So how did you turn it on to get these measurements?

When its plugged in the board is on, I think the relays are stuck where they are on because I hear no clicking or relays when I plug it in, or unplug it or press the power button. There is no power light on the front and no blinking to indicate anything. I assume there is no power light on the front because usually that light is illuminated when the tv power is off(I think).

Perhaps its stuck on and that is how I am able to get those readings. If it were on I imagine the backlights would be lit up also but they are not however.

I have read through alot of the threads pertaining to my model but none have as unique of a situation as this one.

Im leaning towards the problem being the main board but if there is anything else or would like for me test please let me know.

[budm]

Re: Sony 40EX400 Dead Power supply reads good

Yes, it is something on the main board.
One of the fix is the firmware update that you can try:
https://www.badcaps.net/forum/showpo...&postcount=110

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

So your saying this may not be a hardware problem? Interesting... Thanks bud Ill look into those.

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

Im going to attempt to apply the update here momentarily in hopes this fix the problem, my only question is how will I see anything since the screen doesnt currently turn on or work. Do I just assume its working based on the LED lights that are blinking, or supposed to be anyway?

[budm]

Re: Sony 40EX400 Dead Power supply reads good

From what I see on the firmware update for the KDL, you do not need to see anything on the screen:
https://www.badcaps.net/forum/showthread.php?t=24510
Yours may be in worst condition since it does not even show any lights on the front panel.
BTW, try removing cable between the main board and the T-CON board and see if you will get any blinking error codes.

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

Okay, It seems my main board is just dead. Im getting voltage out to everything but the mainboard doesnt seem to do anything. The usb I put the update has an light on it that tells you when its being accessed or read, and it does nothing no matter what combination I try to power on the tv with. I just seems like once I plug the tv in its just on, but its really not. I jumped the standby voltage to the BL_ON and got a light from the screen but only for a split second. Then it goes away.

All voltages read the same as previously, still no progress.

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

Bud, I tried disconnecting the cable from the tcon and mainboard already with no change. No lights on the front nothing. Is there an onboard fuse on the main board because if there is I bet its shot. I dont see one though. Are there even relays on this power board to click, Im not seeing anything like that on this board.

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

I believe I have an problem with the main board right around this area(See picture)

[budm]

Re: Sony 40EX400 Dead Power supply reads good

That looks bad, something got really hot there. I would say it is time for a new main board.

[coreyand]

Re: Sony 40EX400 Dead Power supply reads good

Yea me too, Im looking at this one http://www.ebay.com/itm/SONY-KDL-40E...item1c4e626f4d

[CapLeaker]

Re: Sony 40EX400 Dead Power supply reads good

Ooyyyyyy... New main board it is.