Sony TV model# KV-21GMR1 is a dead set: no LED standby indicator light, +115V supply to horizontal output transistor measured only 27V and is pulsating.
The SMPS regulator IC STR-S6707 was replaced but still the +115v supply line is dropped.
Even when the horizontal output transistor is disconnected from the circuit the +115V supply will not increase.
An ohmmeter check on the SE115N error amplifier shows that it is internally open circuited.
Power was restored to the set when the SE115N was replaced.