netimmerse
Beginner
Monitor was sold for cheap with the following issues - powers on, no vertical/horizontal drive and no EHV as a result.
A spare working deflection board assembly (D+D1) allowed to deduce the problem being on D board.
Scoping vertical IC showed vertical pulse appearing for less than a second after turning the monitor on, measuring +5V power supply to D1 board (deflection control) showed voltage dropping to 1.5-2V at the same time.
The culprit - faulty 7805 voltage regulator (IC1502) on D board stepping down voltage from 12V to 5V solely for D1 board power supply.
A spare working deflection board assembly (D+D1) allowed to deduce the problem being on D board.
Scoping vertical IC showed vertical pulse appearing for less than a second after turning the monitor on, measuring +5V power supply to D1 board (deflection control) showed voltage dropping to 1.5-2V at the same time.
The culprit - faulty 7805 voltage regulator (IC1502) on D board stepping down voltage from 12V to 5V solely for D1 board power supply.