Sony KDL-70W830B backlight repair

[waldo22]

Hi all,

I have a Sony KDL-70W830B 3D TV where it turns on, the front LED flashes 4 times, then it shuts off.

According to Google searches:

....a 4 blink code means either the backlight inverter board is bad or one of the backlights in the LCD panel has failed. It can also be the LD board or main logic board, check inverter board wires for arcing to ground.

I also see that @jeffer76 had what sounds like the same problem in this thread:
https://www.badcaps.net/forum/showthread.php?t=82306


It displays the menu and even the app selection screen briefly (< 5 sec) before it turns off, so this tells me that the LCD hardware itself is fine (I think; please correct me if I'm wrong).

I'm not afraid to take things apart and work on them, but what I don't want to do is spend hundreds of dollars throwing parts at the problem. A set of replacement backlight strips on ShopJimmy are about $100, but I want to make sure that's the correct fix first.

...so what I'd like to ask is, what tests can I do with a multimeter to determine if the backlight strips themselves are bad, the inverter board, or something else like the LED Driver board or T-Con board.

Any repair experts here that can tell me what to test?

Thanks a bunch!

-Wes

[alfatv]

Re: Sony KDL-70W830B backlight repair

There are few things you can do.
First of all identify all connections to LED strips and measure voltages when backlight is on.
If a strip is open, there will be higher voltage across it compared to good strips.
If voltage across good strip is <120V, you can connect normal bulb in parallell with broken strip, this will fool power supply and TV will stay on.

Separate strips without aluminum plates are much cheaper on aliexpress.
The reason they sell it with aluminum plates is because they are parting out TV's and good strips can be damaged if removed. However, if you replace them with new ones, no need to worry about it.
Be very careful with internal glass, it will crack if flexed and your backlight will be really ugly.

[waldo22]

Re: Sony KDL-70W830B backlight repair

There are few things you can do.
First of all identify all connections to LED strips and measure voltages when backlight is on.
If a strip is open, there will be higher voltage across it compared to good strips.
If voltage across good strip is <120V, you can connect normal bulb in parallell with broken strip, this will fool power supply and TV will stay on.

Separate strips without aluminum plates are much cheaper on aliexpress.
The reason they sell it with aluminum plates is because they are parting out TV's and good strips can be damaged if removed. However, if you replace them with new ones, no need to worry about it.
Be very careful with internal glass, it will crack if flexed and your backlight will be really ugly.

Thanks so much @alfatv, this is great info!

I'll do some work and report back.

-Wes