When plugged in, Sony Bravia KDL-40EX401 red standby led blinks 6 times and repeats. After pressing the power button the screen displays "Sony" with a tone and repeats this 3 times before returning to standby and continuing to repeat blinking 6 times. I don't have the service manual but from internet research learned the blinking meant a problem with the inverter board. I replaced the board and after plugging the tv in, the light then began blinking 2 times repeatedly. When powered on, the screen displayed the logo with tone a few times the same as before but after returning to standby the red led was blinking 6 times again and no longer blinks 2 times even after being unplugged and plugged in again. I know the 2 blinks means a power supply problem and suspect that may be the real culprit, but I don't trust the blinking anymore. After further research I tested all the power supply voltages that were printed on the board. 24vdc pins to inverter read 25. The 12v pins for the other connector read correctly, too. How can I determine which board is really at fault? Could this be a problem with the LCD panel, even though it does light up and display correctly, although briefly?

Hi, thanks for responding. Yeah, I should of known it wouldn't give me such a simple solution.

I checked the voltage on BL_ERR and it reads 3.27v in standby. When the set is powered on, it goes to 0 whenever the screen turns on and then returns to 3.27 in between those three times and when it's in standby again. Hi, thanks for responding. Yeah, I should of known it wouldn't give me such a simple solution. <g> I checked the voltage on BL_ERR and it reads 3.27v in standby. When the set is powered on, it goes to 0 whenever the screen turns on and then returns to 3.27 in between those three times and when it's in standby again.

Hmm...I thought I did. I got it off Ebay, described as pulled from a working unit and guaranteed not DOA. Maybe something else I shouldn't of trusted.

Is it possible something else is damaging the inverter boards, because I did get 2 blinks repeating the first time I plugged the set in after I replaced the inverter. After I powered the set on, I never got the 2 blinks again. Is there a way to test whether the inverter board is good? You also say it's possible the BL_ERR reading could mean a problem with the main board. Is there something I can do to check that? Hmm...I thought I did. I got it off Ebay, described as pulled from a working unit and guaranteed not DOA. Maybe something else I shouldn't of trusted. Is it possible something else is damaging the inverter boards, because I did get 2 blinks repeating the first time I plugged the set in after I replaced the inverter. After I powered the set on, I never got the 2 blinks again. Is there a way to test whether the inverter board is good? You also say it's possible the BL_ERR reading could mean a problem with the main board. Is there something I can do to check that?

Okay, I'm willing to replace the main board too if that's where the problem is. I cut the BL_ERR lead going from the power supply to the main board (no problem to solder it back later with shrink tube), but I also cut the BL_ERR wire to the inverter by accident. Hope that doesn't mess up the test. The thing is, the line to the main board seems to be an input. Before I cut it, it read 3.27v at the main board terminal. After the cut it still reads that on the main board and 0 at the power supply. Is that the way it's suppose to be? Anyway, the screen does the same thing: lights up with logo and tone three times and then back to standby. Okay, I'm willing to replace the main board too if that's where the problem is. I cut the BL_ERR lead going from the power supply to the main board (no problem to solder it back later with shrink tube), but I also cut the BL_ERR wire to the inverter by accident. Hope that doesn't mess up the test. The thing is, the line to the main board seems to be an input. Before I cut it, it read 3.27v at the main board terminal. After the cut it still reads that on the main board and 0 at the power supply. Is that the way it's suppose to be? Anyway, the screen does the same thing: lights up with logo and tone three times and then back to standby.

Alright, we're getting closer. When plugged in now I get the audio of the channel but not the picture. Actually, the picture does seem to be there. It's difficult to tell but when I hold a flashlight up to the screen I can barely see the picture. So its just that the backlight isn't staying lit after it turns on for a few seconds to show the Sony logo. Alright, we're getting closer. When plugged in now I get the audio of the channel but not the picture. Actually, the picture does seem to be there. It's difficult to tell but when I hold a flashlight up to the screen I can barely see the picture. So its just that the backlight isn't staying lit after it turns on for a few seconds to show the Sony logo.

Oops, still learning how this site works. I didn't see the rest of your last message and sent a reply. If you didn't get it this is what I wrote:

Alright, we're getting closer. When plugged in now I get the audio of the channel but not the picture. Actually, the picture does seem to be there. It's difficult to tell but when I hold a flashlight up to the screen I can barely see the picture. So its just that the backlight isn't staying lit after it turns on for a few seconds to show the Sony logo.

Also forgot to add that standby isn't blinking anymore. Want you to know I really appreciate your help with this. I realize my measly 15 bucks doesn't really cover the knowledge and experience you guys give generously. Oops, still learning how this site works. I didn't see the rest of your last message and sent a reply. If you didn't get it this is what I wrote: Alright, we're getting closer. When plugged in now I get the audio of the channel but not the picture. Actually, the picture does seem to be there. It's difficult to tell but when I hold a flashlight up to the screen I can barely see the picture. So its just that the backlight isn't staying lit after it turns on for a few seconds to show the Sony logo. Also forgot to add that standby isn't blinking anymore. Want you to know I really appreciate your help with this. I realize my measly 15 bucks doesn't really cover the knowledge and experience you guys give generously.

Oops, again. Thought your last message was the one before. Give me a sec to check BL_ON at the main board. Oops, again. Thought your last message was the one before. Give me a sec to check BL_ON at the main board.

It's very strange. Voltage reads 3.25 for BL_ON at both the main board and inverter board and yet the backlight doesn't stay on. It's very strange. Voltage reads 3.25 for BL_ON at both the main board and inverter board and yet the backlight doesn't stay on.

The current inverter board is a replacement that's suppose to be good, so I swapped the original board back in and the voltages are the same and the tv does the same thing: turns on and I can hear audio but the picture becomes black after the Sony logo and tone. I wondered if it might be dimmed all the way and checked the dimmer voltage. It's 3.2v when the set is first turned on then drops to about 2.2 when the screen comes on with the logo and then drops to 1.6 when the screen goes black. Does that mean anything? The current inverter board is a replacement that's suppose to be good, so I swapped the original board back in and the voltages are the same and the tv does the same thing: turns on and I can hear audio but the picture becomes black after the Sony logo and tone. I wondered if it might be dimmed all the way and checked the dimmer voltage. It's 3.2v when the set is first turned on then drops to about 2.2 when the screen comes on with the logo and then drops to 1.6 when the screen goes black. Does that mean anything?

Could I use the 3.3v standby voltage pin on the power board? Could I use the 3.3v standby voltage pin on the power board?

Alright! Guess that was it because I've got the picture now too. Closest resistor I had handy was 2.2k and first used the 3.3v standby pin but I forgot to cut the lead to the dimmer and it didn't work. So I used 3 volts from a universal power supply with the 2.2k and of course still didn't work until I realized the lead from power supply needed to be cut. So the standby voltage probably would work. So would a solution be to run the set jury-rigged like this or do we know which board needs to be replaced? Alright! Guess that was it because I've got the picture now too. Closest resistor I had handy was 2.2k and first used the 3.3v standby pin but I forgot to cut the lead to the dimmer and it didn't work. So I used 3 volts from a universal power supply with the 2.2k and of course still didn't work until I realized the lead from power supply needed to be cut. So the standby voltage probably would work. So would a solution be to run the set jury-rigged like this or do we know which board needs to be replaced?

Great, thank you. I went from thinking the tv might be a lost cause to having a working set and knowing the right possibilities for a more complete repair. I'm very satisfied and will be accepting this solution. Thanks again. Great, thank you. I went from thinking the tv might be a lost cause to having a working set and knowing the right possibilities for a more complete repair. I'm very satisfied and will be accepting this solution. Thanks again.