budro
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Aug 15, 2012, 3:18 AM
Post #1 of 1
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Sony KDL-46S4100 no backlight video or audio
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I have a Sony KDL-46S4100 that the backlight will not come on. Power light turns on steady no flashing. Even with a source plugged in you cannot get the input to switch to it to turn on the screen. If I disconnect connector CN303 I get the Blue, Red, Green test pattern. So I know the inverter board, panel and backlight work. I tried a different main or A board and had the same results they both have the exact numbers just different serial's at the bottom. Tested the fuse on the T-con board and getting power through it. Here are the voltages I am getting at the power supply connectors:
Powered ON:
CN301
1-15.71v
2-15.71v
3-0v
4-0v
5-7.18v
6-0.01v
7-3.44v
8-3.44v
9-3.43v
10-0.01v
11-0.01v
12-0.01v
13-11.60v
14-0.00v
CN301 Powered Off:all are 0.00v except pins 2,7,8,9 these are 0.05v
CN302 Powered on Powered off
1-0.00v 1-0.00v
2-0.00v 2-0.00v
3-3.28v 3-3.29v
4-3.28v 4-3.29v
5-0.00v 5-0.00v
6-0.00v 6-0.00v
7-0.02v 7-3.28v
CN303 powered on Powered off
1-0.00v 1-3.25v
2-0.17v 2-0.06v
3-N/C 3-N/C
4-1.69v 4-0.22v
5-0.00v 5-0.00v
I know pins 1 on CN303, 1 on CN302, & 7 on NC302 are all low voltage or 0volts which control the backlight circuits. My question is do these voltages come from the power supply or are they returned to the power supply board from the main or A board?
Any help would be greatly appreciated. I have ordered a power supply but wanted some others opinions as well.
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