I have a sony color rear projector model kdp-51ws550 seial 9710095 manufacture june 2004 it turns on and it goes off the stand by light keeps blinking

Hi there,

Well If you simply push the power button on the front, does the stand-by LED turn off or start flashing? Anyway the G Board is definitely suspect. Try measuring the 5 volt DC stand-by power supply. That is best done at connector CN605, between pin 10 and cold ground (any metal chassis part). 

If that voltage isn't there, carefully measure the voltage across resistor R607 ( not to any ground). You should get something very low, a couple of volts (if that much). If you get a couple hundred volts, that resistor is open, and that happened because transistor Q601 shorted.
Note. You need a ohms meter to check that all. please do not try this if you do not know how to do that.......
Please post comments for more help or information........

Good Luck!!

Thanks