N Cook wrote:
Dead power supply. I've the schematic for the JVC HR J725 of which
the ps seems much the same. Secondary side of the switch mode
transformer fed forwards through an opto isolator to the HV switching
power FET.
No oscillation ,all circuit protectors OK, removing the main driver
FET it tests ok. How to locate such a situation where there is no
obvious oscillator/controller IC.

Many JVC's need a 1 uF at 250 volts (or so) in the primary, and a 120 uF at
6.3 volts cap on the secondary. Obviously one might just replace all suspect
electrolytics, though...

Mark Z.