the result is compared to a reference voltage. The reference voltage is provided by a zener diode. If the output of the comparator goes high, Q6741 turns on effectively grounding the SOS line. The SC board uses a similar circuit to monitor the +17V line.
The SS and SC boards contain an LED indicator to alert the technician when a problem exists. The LED should be lit during normal operation, a dark LED indicates that a problem exists on that board.
37
