Sony KV-27S66

Whenever it is left plugged in for a few minutes up to one hour, it is dead.  Unplugging it for a few seconds gets it to work, only to have it go out again whenever it has juice.  Replaced the EEPROM and quartz oscillator,  no results.  I measured the both the 5 v and 7.5v STANDBY test points on the A board. The 5v is 5 volts, but the 7.5v measured at 7.61 and sometimes 7.55.  H owever, when the set plays dead, the voltage jumps to 7.68-7.70. The 5v stays at 5 volts regardless.