Sony KDL-46BX450 No Power

[arod]

Hi all,

I received a Sony KDL-46BX450 from my grandparents who had a technician come to their house to diagnose their tv and fail to repair it. My grandparents had a warranty on this and were able to get a new television out of this deal, thus me inheriting the TV. The issue that I have is the standby LED blinks 6 times repeatedly once the TV is plugged in (no video or audio). I have attached the service manual for this TV to this post.

The repair guy thought it was the power board and ordered a new power board for the television, but it failed to fix the issue (same problem). After receiving the tv and reading the service manual myself, it seems like it could be the inverter board which has gone bad. There is no visible damage to the board or anything suspicious when looking at it. I connected my multimeter to a couple of the lines, but I am unsure what would be considered normal. The unregulated 24 volt line that goes to the inverter is initially around 24 volts when initially plugged in, but drops to 0 (or close to 0) very quickly after the TV has been plugged in. My theory is that if the inverter board was bad, then the main board would immediately shutdown that circuit. However, without a more detailed description from the service manual, I am just guessing here.

Normally, I would take the risk and just purchase a used inverter but they cannot be sourced unless I go through aliexpress and it is quite expensive with a long leadtime for delivery. Does anyone have any suggestions for further testing to isolate the issue with this television? I noticed that shopjimmy has a repair service for the inverter board and perhaps I might be able to do similar diagnostics as them to fix it myself. Any help is appreciated...

BTW, the backlight inverter p/n is LJ97-03319A.

[freakaftr8]

Re: Sony KDL-46BX450 No Power

Unplug the TV wait 30 seconds hold down the power button while you plug in the TV still holding the power button. Does the back lights come on do you see a picture before it shuts down with a 6 blink error again

[arod]

Re: Sony KDL-46BX450 No Power

Unplug the TV wait 30 seconds hold down the power button while you plug in the TV still holding the power button. Does the back lights come on do you see a picture before it shuts down with a 6 blink error again

The backlight never turned on when trying this

[freakaftr8]

Re: Sony KDL-46BX450 No Power

Ok when you plug the TV in as you are still holding the power button as soon as you plug the TV and wait three seconds release the power button. This is done on the TV not the remote. Do you have an initial click a pause and then the six flashes

[arod]

Re: Sony KDL-46BX450 No Power

Ok when you plug the TV in as you are still holding the power button as soon as you plug the TV and wait three seconds release the power button. This is done on the TV not the remote. Do you have an initial click a pause and then the six flashes

As soon as the television is plugged in, the standby LED begins flashing (no pause). I tried to mimic your procedure several times and there was no clicking when releasing the power button.

[arod]

Re: Sony KDL-46BX450 No Power

Are there any other suggestions for helping me to isolate the inverter board? The fact that the board never lights the backlight suggest to me that the inverter board is most likely the issue.

[budwich]

Re: Sony KDL-46BX450 No Power

Have possibly tried "starting up" the set with the inverter board unplugged to see if you get a different code or possibly no code, depending on what happens.

Further: you could try monitor the "err" lead, to see if there is any change.... could be tough but since you are good at the "24v" stuff, hopefully the other one is equally accessable. I would think it should go to some form of "high" for an "error condition".

Lastly, of course, you checked all the fuses on the inverter board... :-)

[arod]

Re: Sony KDL-46BX450 No Power

Have possibly tried "starting up" the set with the inverter board unplugged to see if you get a different code or possibly no code, depending on what happens.

Further: you could try monitor the "err" lead, to see if there is any change.... could be tough but since you are good at the "24v" stuff, hopefully the other one is equally accessable. I would think it should go to some form of "high" for an "error condition".

Lastly, of course, you checked all the fuses on the inverter board... :-)

I received the same error code (6 blinks) with the inverter unplugged. I checked the fuses first thing when I suspected the inverter. They are all good. I will try to monitor the err lead shortly.

[budwich]

Re: Sony KDL-46BX450 No Power

"while you are there", you should also check the "ena" to see if the system is trying to turn on the BL. Possibly, the error counts are passed a threshold and it doesn't even bother... just "erroring" instead.

[budwich]

Re: Sony KDL-46BX450 No Power

I would try "redoing" the "reset procedure". I have seen reference to power the tv on... wait a bit to ensure it has "done something".
Point the Sony remote control at the TV and press and hold the "Up" arrow button.
Push the "Power" button on the TV while holding down onto the "Up" button. Release the "Up" button when the TV turns off, then turns back on. Hopefully it will clear any errors and light up... maybe

[arod]

Re: Sony KDL-46BX450 No Power

OK, when I plugged in the tv to attempt your reset procedure, the backlight came on (for 1 second before shutting off)! No idea what has changed other than a couple of reseats of the inverter board. However, now the buttons on the side of the television do not appear to have any effect. The standby LED is also a solid green now. There are no error codes.

On subsequent power offs (via the remote), the television will display the SONY logo for a second before the backlight turns off. The TV is still powered as the standby LED remains solid green during the entire time. It seems like this is most definitely the inverter board. Any last thoughts before I bite the bullet and order a new inverter board?

[budm]

Re: Sony KDL-46BX450 No Power

That inverter board is known for having bad inverter transformer:
https://www.badcaps.net/forum/search...archid=5567121

[budwich]

Re: Sony KDL-46BX450 No Power

OK... so now at least you got something to change. So not withstanding the experienced advice given by budm (of which I have little), the trouble shooting steps outline in the SM appears to point to the panel.... maybe although other steps possibly indicate the inverter board. I would try a few more of the trouble shooting steps to see if anything else shows up to point direction.

Since it appears now that you can "move" the sets responses in a certain direction with some "keying / buttons", I would go back and pull the connections to the inverter again... what happens, do the error codes reappear? Further, there are other tests such as pulling the lvds cable to see that response. Combination of these "pulls" may help your decision.

Further, maybe the "flashlight test" will help to see if there is a display but no backlight. In addition, when they (the SM) are indicating a "panel problem", they might mean that for instance the backlights are not readily replaceable hence the panel problem / replacement.

Lastly, when the backlights momentarily came on, did you notice any "uneveness" in the lighting, that might point to a backlight issue in some form?

[arod]

Re: Sony KDL-46BX450 No Power

Just an update, but I purchased a new inverter board from buyqual.com in China. This fixed the issue. TV works normal now with the new board installed.

[budm]

Re: Sony KDL-46BX450 No Power

Thanks foe the follow-up on the repair.

[freakaftr8]

Re: Sony KDL-46BX450 No Power

Nice job!