Kdl-32bx400 green led on, restarting every 30sec

[lazevedo]

Hello

I have a faulty Sony Kdl-32bx400.

When i connect it to the plug the green led imediatly turns on.

After that, sometimes the backlights turns on i got sound and the sonny logo appears, sometimes nothing happens(no sound, no picture and no backlight).

It remains in this state for aprox. 30 seconds and the restarts.

After the restart green led stays on and nothing happens for 30 seconds and then it restars again.

The TV doesn't answer to any command from the remote.

Already check readings from connectors. I have voltage in Standby(3,2V), Power(3,2V), 12V is at 12,5V, BL_ON is 0V, and BL_error is about 3V.

Already disconnect BL_error on the inverter and ground BL_error on the main board with 110ohm resistors. BL_ON normaly stays at 0V even with this modification.

Already disconnect dimmer pin on inverter board.

Nothing changed with all this modifications.

I kindly ask you for your help because i am out of ideas

PS: Since the beggining this TV as a small defect, a vertical yellow line appears when the screen is on with the background color black.

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Attached pictures from the TV.

Thanks.

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

With tv unplugged from outlet, unplug cable from mainboard to powerboard, plug tv back in outlet, turn tv on and see if backlight comes on and stays on.

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Hello nomoresonys

Thanks for your reply.

I follow your instructions and no backlights after plug in.
StdBy : 3,2V
PowerOn :-1,7V

The other pins are all 0V.
Also the 24V going to the inverter is 0V.

Regards

[Andrew F. Ali]

Re: Kdl-32bx400 green led on, restarting every 30sec

Appears to me that you have a Main Bd problem and to be more exact corrupted software.

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Hello

Thanks for your comment.
What can i do in order to proper diagnose the problem?
If this is the problem can it be solved with new Nand memory?

Regards

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

Check F001 fuse on inverter board.

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

If this kdl has pullup resistors, when unplugging mainboard from powerboard, backlights should have come on if powerboard and backlight circuit are ok.

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

Maybe get one of the pros to help you jump start the powerboard by itself to see if your voltages come back to normal.

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Hello

Thanks for your help.
F001 is ok.
I've been checking the powerboard diagram attached on page 21 and it seems that the signals are not pulled up(I'm not an expert).
I think BL_ON is generated in the main board and the inverter board feedbacks BL_ERROR. Is it like this?

Regards

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

Yes bl-on signal comes from mainboard, when testing the powerboard by itself, cable from powerboard to mainboard should be unplgged, then maybe use 1 k resitor from standby pin to power on pin and another resistor from standby pin to bl-on pin, see if backlights and voltages come up to normal, MAKE SURE cable from powerboard to mainboard is unplugged for this test.

[Andrew F. Ali]

Re: Kdl-32bx400 green led on, restarting every 30sec

What is the StdBy voltage as measured on the connector going to the Main Bd and the TV just plugged in the wall 120Vac?

[budm]

Re: Kdl-32bx400 green led on, restarting every 30sec

You do not notice the LED blonking pattern at all?
Backlights error will gibe 6-blink error code.

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Hello

Thanks for your comments.

I remeasured stdby voltage When pluged to 220v and is 3,3v regardless of the connector going from power to main is connected ir not.

Regarding blinking error codes i don't see any blinking, and the tv doesn't go to stand by mode after restarting. It just shutdown and return to on state(green led on) every 30 seconds.

This afternoon i Will do the connection sugested by nomoresonys as i'm already late for my day job... i Will feedback the results.

Thanks for your help

Regards

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Hello

I gave 3,3V to PowerOn and BL_On and Baclights turned on normal and sustain the normal state for some minutes. So the inverter board is ok and power to Inverter is OK(I think!).

Should i make the same debugging to the T-CON Board, i mean, check if when powerboard receives TCON on it delivers the 12Vcc to TCON? If yes, is the 3,3V the voltage to be deliver to TCON_ON?

Regarding the main board is there anything i can check or do?

Once again, thanks for your valuable help.

Regards

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

After that test, it's looking like the mainboard is the problem.

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

Take the cover off tcon, check fuse and see if you have about 12 volts on each side of the fuse, red probe to each side black probe to a ground.

[lazevedo]

Re: Kdl-32bx400 green led on, restarting every 30sec

Hello nomoresonys

Thanks for your reply.

That was my intention but for that i have to deliver the 12V from the mainboard wich only is available on TC_ON is high. Other problem is that on my model the voltage and ON signal pass through the main board and i do not know how can if i can do it.

Is the logical level of TC_ON 3,3V?

Can i cut the TC_ON wire from main to power jump it with 1k resistor from stdby and woud have power on TCON?

By the way, do you have any experience on copy flash memory?

Regards

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

Not exactly sure on this model, test fuse on tcon to make sure it isn't blown, there might be a test point on tcon close to where the lvds cable plugs in, should be around 12 volts.

[nomoresonys]

Re: Kdl-32bx400 green led on, restarting every 30sec

You should be able to unplug lvds on mainboard side, and see if the 12 volt pin has proper voltage, trick might be finding which one it is without schematic.