Sony Vega TV , On off switch

Three flashes is lamp cover/lamp position error, it means the lamp cover is not set right, or the lamp is not in the right position. There are two micro switches to detect the lamp position, and lamp cover. Please reset the lamp and the lamp cover (door).

Make sure your lamp door is completly latched. there are saftey switches in your set that will not let the TV operater if not properly closed.

CHANGE THE LAMP

You might have a bad B board. What's worse is that the power switch is connected to the Q board which works in conjunction with the B board. Replace B board, You can send your B board for repair to a company called modus link pts. They are the largest part supplier of after market parts and repair.

MY SONY PROJECTION TV WENT BLANK WITH NO SOUND GREEN LIGHT WAS ON WHATS WRONG

There is a real good chance that the lamp fan is not turning. If you look with a flashlight in the vent on the left side looking at the rear of the set and have someone turn on the unit, see if it spins. if it doesnt, the protect circuit in the tv will not let the set turn on. Replacing the fan will cure the proplem if it is not turning.
Hope this helps,
Skyassoc

Here's an excerpt from the Sony Manual online. And the link - http://esupport.sony.com/US/perl/webtree.pl?template=EN&mdl=KDF55XS955&content_id=68&category_id=11&problem_id=52

The POWER/STANDBY (red) indicator flashes three times
If your power/standby indicator is flashing in a pattern of three flashes, this may indicates that the lamp cover is not attached securely. Follow the directions in the Operating Manual under changing your lamp that related to closing and securing the Lamp Cover. Ensure that the Lamp Cover Door is securely fastened by tightening each screw.

The POWER/STANDBY (red) indicator flashes continously
If your power/standby indicator is flashing continuously, and the lamp cover has been secured, your TV may be in need of service.

The POWER/STANDBY indicator is lit up green (not flashing)
A sustained green light indicates your TV is on.

The POWER/STANDBY indicator is lit up red (not flashing)
A sustained red light from your power/standby indicator simply indicates that your TV is in standby mode. This shows you that your TV is ready to be turned on with the remote.

Is it the power light and not the lamp light? If the lamp light is flashing then replace the lamp.

KV-32HS510 and KV-27HS420, seven times blink error code shows problem in Horizontal deflection circuit.

There are many possibilities like dry solder joints, weak capacitors, Horizontal transistor short or flyback transformer fried etc.

If you have little experience of TV repair and good solder skills and have necessary tools to test / check defective parts, then you can make it. you also need to have related service manual to see board location, schematics and part numbers.

There is some electronic circuit problem with your TV. Best if you want to repair it you find a reputable TV repair shop. Sorry.

This unit shouldb e flashing a repeated count on the standby light. That count will indicate the circuit in which a problem was detected causig the shutdown. Please post that count and we should be able to provide details on the repair.

Thanks,
Dan