1592: Internal Power Supply fault.
Pre-DRV
HCPL7800  -3.
FAN 24v 
7&8 pins for start. 3&4 CURRENT INPUT 4-20mA.
Numeration from right side.
Tested.
2682: Capacitors, 7800, int. contact (+20V), 74AC240.
Tested 4-20mA.