870: Internal Power Supply fault.
All capacitors changed.
Repair PCB after heating.
Pre driver PCB: 1k for soft start and 1k x4 for HCPL7800.
HCPL7800  -3,
Repair the power board: 
changed SS-resistors 22R (10R+10R)
7&8 pins for start. Numeration from right side.
Tested.
1081: Replacement Pre driver board after repair.
FAN 24V.
Tested.