TM 11-6625-3041-30/TO 33A1-8-908-12
1-24. MULTI VDC (A1) START (CONT)
Switcher
With the Switcher running dc outputs are available, in-
cluding that from the Run Ref whose output is +12V.
Ref Sel
The +12V Run Ref is applied through CR4 in the Ref Sel
circuit and backbiases Q1, which turns off. The Ref Power
voltage thus becomes the +12V Run Ref and is used to maintain
power to the Sens, Sens Sum, and Clock circuits.
The +12V Run Ref voltage is also applied to the top of
Start/Run
voltage divider R66-R64. The voltage at the junction of R66-
Sens
R64 is 1/2 x 12V = 6V and is applied through CR37 to the
positive input of the Start/Run Sens at U5-7. This keeps the
output of the Start/Run Sens at U5-1 high, which keeps the Clock
and the Switcher running.
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