Personally it looks like either you have the incorrect mainboard replacement or it too is faulty.
It is kinda looking like it may be faulty as well. All of the numbers match on the new board with the exception of the white barcode label. On that label the first 6 0r 8 number match, then the rest are different.
Let me ask this, does the main board tell the inverter board to turn on via the 3 wire connector CN202 on the main board?
Yes, and you have already proved using the two boards that the standby voltage brings up all the other voltages and the second board when forced to power on brings up the picture and backlights so no inverter problem.
Go to Shopjimmy website and enter the board numbers and see if they come up as compatible.
Ok, I entered the 48.71I01.011 and it brought up 6 boards. Out of the 6, two had my tv model number listed. Of the 2, one matched the rest of the numbers and one did not.
They have 3 different Sony part numbers listed, but I cant find a Sony part number on either of the boards I have.
All the numbers on my old board match up with the new board, except for the white barcode label. The first 11 digits match on it, and the rest do not. Pics below. The 4th pic is the barcode label of the new board. I don't know if that barcode label not matching makes a difference or not.
No backlights. I tried the flashlight test, but I didn't see an image. That board on shopjimmy looks the same, but I will post pics of it in just a minute. The pins on the main board are not labled that i see. The pins on the inverter board are labeled. I will see what the voltages are and list them.
On his original mainboard he had to force PS_ON to get the set to power up and run as normal. So it looked like the mainboard was not sending out PS_ON.
On the replacement mainboard he has PS_ON and the power comes up but it does not provide BL_ON or DIM.
I was messing with this again this morning and saw that along with no BL_ON and DIM voltage from the main board, that I also have no power on or STBY led indicators lit up on the front of the TV. Something else I found is that the PS_ON pin has voltage on it wether I press the power button or not. As soon as I plug the TV in the PS_ON pin goes hot, and stays hot regardless if I press the power button or not.
I don't know if this will help or not but I worked on the same model tv. It would not do anything but I had good voltages. Replacing the main board fixed the original problem. It worked for a little while, then would not turn on. If you unplugged the power and left it unplugged for a while, then when you plugged it in and turn it on it worked. I never managed to find the problem, I just put a surge strip on it and left the strip turned off until I wanted to use it. Then first turn on the strip and then the tv would come on just fine. That was not a problem for the customer so that is how it is being used today. This might be something to try.
I don't know if this will help or not but I worked on the same model tv. It would not do anything but I had good voltages. Replacing the main board fixed the original problem. It worked for a little while, then would not turn on. If you unplugged the power and left it unplugged for a while, then when you plugged it in and turn it on it worked. I never managed to find the problem, I just put a surge strip on it and left the strip turned off until I wanted to use it. Then first turn on the strip and then the tv would come on just fine. That was not a problem for the customer so that is how it is being used today. This might be something to try.
No go. Doing the same thing.
I talked to shopjimmy, they confirmed the board I bought will work with this tv. I talked to the guy I bought it from, he is looking to see if he has a board he can exchange the one I bought with.
have you done a firmware update on the new board, I had a kdl 40ex523 which went off in a store but didn't show any standby Led etc however all psb voltages where good going to the mainboard upon closer inspection the main processor had the glorious rainbow colour surrounding it that you get when you heat it up far too much lol. I replaced the board and done the firmware update although the update itself took over a hour (exact time unknown as I let it run overnight) just something to try
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