The 3 blinks indicate the lamp door is not shut. This can also be caused by a defective lamp door switch. See page 51 of the owner's manual for information on replacing the lamp and securing the lamp door. Click here if you need to view or download the owner's manual. Click here to view an alert Sony has on this TV. The alert is not about the problem the TV is having at this time but I thought you might wish to be aware of the information.
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Sony provides blink codes to their service technicians as s starting point to start looking for repairs. The 70 blinks is not a Sony blink code. If you have never replaced the lamp in this TV there is a 99% chance that replacing the lamp will correct the problem. Even new lamps can become defective. Actually most lamp failure occurs in the first 30 days of operation. Power supply failure is also possible and this would be my second choice to look once the lamp is ruled out as the problem. The only way to know for sure what is causing the problem, which parts that are no longer within factory specs and for proper repair all the electronics must be diagnosed by someone with the correct electronic test equipment and the skills to use the test equipment. If you feel qualified to diagnose and repair the TV I will suggest that you click here for the service manual for this TV. Click here to purchase the needed service manual if the download is not working.