Sony kdl-52xbr9 13 blinks standby light, no backlight

[topfli8979]

Have a sony kdl-52xbr9 with no backlight, will power on then relay clicks and get 13 blinks from standby light. At 12v vcc pins from power supply im getting 3.6 volts way under the 12v needed. So i need to be looking on the secondary half of the power supply for the fault? Can the main board hold the voltage back if its faulty? If I unplug all boards from power supply should i get 12v at pin?

[tom66]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

If the main board is shorted then the power supply voltages can be low. Also depending on the design of the power supply, a short on one rail can cause others to sag or go missing entirely.

To activate the PSU you should jumper PS_ON to 5V. I like to use a resistor about 100~470 ohms to protect the power board from over-current.

[budm]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Service manual:

According to the manual, 13-blink is BALANCER D4N, D5 board.
Can we see the whole backside of the TV?

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

I also saw 13 blinks can be faulty panel, hoping not. Figured I should get 12 volts to inverters first.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Can I jumper from power supply on to 12v? I don't see a 5v pin.

[budm]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Did you download the service manual?

[tom66]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

You can use STBY 3.3V to POWER ON, don't forget to use resistor.

[tibimakai]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

This not a bad CCFL tube? At least on some other Sonys I had this problem.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

I did downlad manual, thanks for link budm. Jumpering from 3.3v to power on, power supplu made no difference. How does the panel communicate with the main board if its faulty. Voltage should rise to 12v then back off I would think, if fault detected.

[tom66]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

No communication from panel, it will detect shorted T-con, no comm from T-con board, or inverter/BLU fault.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Ok, thanks tom. I get slight rise from 3.2 v to 4.8v with tcon disconnected. Im going to take a look at tcon.

[tom66]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

I'd look at power board. If t-con was shorted that would have gone to 12V.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Ok, on power supply secondary side found a fet short 3-leg N9b fch30a04. Shorted across both rear legs, 1and3

[tom66]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

That is a diode, it goes across a pair of transformer taps so the outer pins will appear shorted, this is normal.
Do you have an oscilloscope available? Maybe try checking if the output is unstable - could be bad output capacitors.

[budm]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

That is dual rectifier diodes wit common cathode, the two outer pin will show low resistance of they are connected to the secondary winding of the transformer, that is normal. Its the resistance between the middle pin (Cathode) and the two outer anodes that you need to worry about.
If you look at the service manual you will see how it is connected.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Sorry for delay, been out of town. I was able to put a new resistor in place 3.3v to power on on the pcb. I have 12v going to tcon,and other boards now. But still no backlight, same 13 blinks. Another forum mentioned bad ccfl bulb,but wouldnt the screen try to prime before it shutsdown? Im getting no flash of backlight.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Is it possible force the backlights on by jumping the pin? Disconnecting does nothing.

[tibimakai]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

You should post some pictures with the power supply connectors.
You can most likely jumper something like BL_ON with a resistor from STBY_ON.

[topfli8979]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Ok guys, been a while since I looked at this tv, got about 8 high end smart tv's in that required my attention first. Anyhow I am able to jumper bl-on, on the power supply to 5v pin and I can get the backlights to come on. I still getting 13-14 blinks at standby light, number of blinks change every few attempts.

[nicholas1110]

Re: Sony kdl-52xbr9 13 blinks standby light, no backlight

Hello,

Have you tried to disconnect the ribbon cables from the tcon to the panel? This model was well known for the panel failing (sony even had a extended warranty for this model). If the tv turns on properly with all ribbons removed then try each ribbon until you get the error code. This will tell you which section on the panel is shorted. Hope this helps out.