Sony KDL-52XBR9 LCD TV 6 red flashes

[tech2014]

I have an LCD tv that does the following:

I turn on the power, the backlight/screen comes on for a couple seconds, then shuts off, turns on again for a couple seconds, shuts off, then on and off again. Then the tv shuts down and i get 6 flashes on the power LED. See pics of inside tv below:





The error codes are for a backlight problem. Manual says D4N board, main board , inverter board,or power supply. I have tried removing connectors from each board one at a time(other then the main board), and I still get the 6 red flashes.

I get nothing on the bal error or inv error pins, stays near 0v. I do get 3.2V on back_light pin for a couple seconds then goes to 0 volts. The backlight pin gets its voltage from the main board, so I would assume the main board is ok.

Can anyone suggest anything I can do to narrow down the board causing the problems. Thanks in advance.

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

All the voltages come up as they should on the power supply, albeit for a short time. 3.3v standby is always there so p/s should be good. Any suggestions?

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Try service mode.

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

I tried and for some reason I can't get into service mode.

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Try

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

If no backlight then you need to disassemble the matrix.
Lamp check.

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

And invertor check.

[budm]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Keep the DCV meter on CN6903 pin 1 (inv error) of the D4N Inverter board before the power switch is activated and after the power switch is activated.
I have a feeling one of the two inverter boards (D3N, D4N) is not working.

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Enable INV Voltage = ?

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

thanks guys. I will check and get back to you with the results.

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Hi budm. I tested pin 1 of CN6903. When I first plug in the tv, the voltage is 6.3v. After about 30 seconds it goes to 0v and tv clicks. The LED flashes red and voltage is 0v at pin 1 of CN6903. Turn power on and voltage goes to 6.3v then a few seconds later tv shuts off and voltage on pin 1 drops to 0v.

[budm]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

I look at XBR6 manual which has similar setup as the XBR9.
The INV_ERROR and the BAL_ERROR pins (CN6204, CN6201 on the power supply board) normally LOW as you have indicated in post 1.
But do you see those two pins stay LOW and never did jump up high at all?

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Maklaud- The pic you posted with the 470 ohm resistor is that to test the backlight and force it to stay on.

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Hi Budm. The voltage stays at 0 volts on BAL_ERROR, but when backlight comes on the voltage jumps from 0 to between 0.6-2 volts on the INV_ERROR pin.

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Disassemble the matrix.
You need another person.
90% that the problem is in the lamps.
Don't be afraid!

[Maklaud]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

What model is matrix?

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Hi Maklaud. I appreciate the help but I am not going to disassemble the matrix, thats too much work. I want tot rule out the panel in other ways.

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

ok with D4N board connected to the D3N board, I measured the inv_error pin on D3N board and it measures 6.3V. When I remove the connector from the D4N board on the D3N board, the voltage on the inv_err pin measures 0V. I guess this means D4N invertor board is defective. Since there is a schematic, is it possible to repair rather the replace the whole board.

[budm]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

"When I remove the connector from the D4N board on the D3N board, the voltage on the inv_err pin measures 0V." I am curious, did you still see the screen flashes on for seconds also? It should if DN3 is OK.

[tech2014]

Re: Sony KDL-52XBR9 LCD TV 6 red flashes

Yes the screen does flash for a second.