TM 11-6625-3041-30/TO 33A1-8-908-12
1-28. MULTI VDC (A1) FAULT SENSING (CONT)
If any Sens output goes low it sets the base of Q4 low. Q4
Sens Sum
conducts and sets the base of Q3 high, which conducts and
lights board fault lamp DS1. It also applies a high level to
the DC Supply Fault Sens circuit on the AC Input card, which
lights both the POWER SUPPLY and FAULT front panel lamps.
If any Hi Sens output goes low it not only lights the fault
lamps. but also applies low level to the Crowbar Driver nega-
tive input at U2-4. This sets the output of the Crowbar Driver
high, which turns on the Switcher Crowbar and prevents the
Switcher from operating.
1-42