Sony KDL-46Bx450 Backlight problems

[bigern26]

Hello all,
I am looking for help on my Sony tv. We were watching tv the other night and it just shut off, came back on and then went black but had sound then shut off again and the red light blinked 6 times.
I unplugged it and brought to the basement to see if I could figure out whats wrong and when I plugged it in with the back off the standby light was solid so I hit the power button and it turned on and showed the sony logo then went black but stayed on with no blinking light.
After doing a bunch of research and troubleshooting I finally grabbed a flashlight and I can see the menu screen and have sound. So my backlights are shutting off after a second.

I have unplugged the Tcon board and the backlights did the same thing.

So testing everything I am thinking either I have a bad bulb or bad inverter. but I am not sure how to test the inverter.

I will post up my voltages of my pins.

TV plugged in but not turned on(standby light on)
CN6401
STBY 3.3v - 3.32V
AC OFF DET - 3.05V
POWER ON - 0

Everything else is 0

TV on and stand by light green
CN6401
STBY 3.3V - 3.31V
AC OFF DET - 3.04V
POWER ON - 3.29
AUDIO12V - 12.6
AUDIO12VGND - 0
REG12VGND - 0
REG12VGND - 0
REG12V - 12.6V
REG12V - 12.6V
BL-ERR - 1.64V
BL ON - 3.12V
DIMMER - 1.67V
TCONVcc12V - 12.56
TCON ON - 3.31

CN6402 BOARD
UNREG24V - 25.3V
UNREG24V - 25.3V
UNREG24V - 25.3V
UNREG24V - 25.3V
UNREG24V - 25.3V
GND - 0
GND - 0
GND - 0
GND - 0
GND - 0
BL ERR - 1.64V
BL ON - 3.13V
DIMMER - 1.67V

I am not 100 sure if I should get the inverter as I read that a bad bulb can cause this. Is there a way to test the inverter?
I do have the manual for this but that was not much help.

[CapLeaker]

Re: Sony KDL-46Bx450 Backlight problems

Nice straight shot pictures of the boards please.
So far I can tell that the main board is sending correct signals to the PSU and Inverter. So we would have to have a close look on to the inverter board.

[bigern26]

Re: Sony KDL-46Bx450 Backlight problems

Here are the 3 boards. I didnt want to take the cover off the Tcon unless I have to.

[budm]

Re: Sony KDL-46Bx450 Backlight problems

That Inverter board looks familiar.
What is the P/N on that inverter board?
This one? Samsung LJ97-03319A Backlight Inverter (Sony 1-857-986-11)
http://www.shopjimmy.com/samsung-lj9...-inverter.htm#
Pictures provided by shopjimmy.

There are many threads about this board and has bad transformer.
https://www.badcaps.net/forum/search...archid=5691709

[bigern26]

Re: Sony KDL-46Bx450 Backlight problems

Part number SSI460_12F01I think. Not sure where it is.

[budm]

Re: Sony KDL-46Bx450 Backlight problems

See post 4.

[bigern26]

Re: Sony KDL-46Bx450 Backlight problems

How do I test the transformers?

[budm]

Re: Sony KDL-46Bx450 Backlight problems

If you look at the picture, the four terminals on the bottom row of the transformer, make left most pin as pin 1, so you have pin 1~4.
You will check the resistance of the first winding which is pin 1 & pin 2, then check the second winding which will be pin 3 & pin 4.
Report the readings of each transformer, the resistance should be within 3% from each others. Look real close at the transformer and the bottom side of the board to see if any one of them show a sign of over heat.

[bigern26]

Re: Sony KDL-46Bx450 Backlight problems

I think I fount the problem. See picture.

Tranformer readings
1 - 1308
2 - 1314
3 - 1154 - the one in the picture
4 - 1316
5 - 1349
6 - 1343

[budm]

Re: Sony KDL-46Bx450 Backlight problems

You may want to contact this person to see if he still has the broken board that you take one of the transformer out to use in your board:
https://www.badcaps.net/forum/showth...19A#post612126

[bigern26]

Re: Sony KDL-46Bx450 Backlight problems

Just sent a message to see. Thank so much for all the help. I didnt know where to begin on testing the inverter.

If that one is gone it looks like I can get a board from shopjimmy.com

[CapLeaker]

Re: Sony KDL-46Bx450 Backlight problems

bad transformer... I thought so... anyway... good luck!

[geeforce]

Re: Sony KDL-46Bx450 Backlight problems

Hey all,

Posting this here as it's super applicable.

I definitely think this tv I have has the bad transformer issue.

I'm concerned about the audio and video issue though. Does it seem like mainboard problems also or could this all be caused by the bad transformer.

Really not interested in investing much on this lol

Cheers,!

Video for what mine is doing

https://youtu.be/lzGEOG1g9wE