Mitsubishi V19-V21, Tehnical Manual

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5-2
Standby Supplies Regulator
Figure 5-1 illustrates the Standby Switch Mode Regu-
lator. Since its’ operation is similar to that in previous
models, a lengthy description is not required. Key points
of operation are:
1) D9A01 supplies DC power to the regulator.
2) Start up voltage (16 volts) is supplied by
R9A22 to pin 4 of IC9A20.
3) The signal at pin 2 of T9A20 is rectified by
D9A22 and adds to the voltage at pin 4 of
IC9A20. If the voltage drops below 11 volts
the oscillator shuts Off.
4) Feedback for regulation is from the STBY 12V
supply through IC9A21 and PC9A20 to pin 5
of the IC9A20.
5) Over Current Protection is provided by
directing the voltage at the pin 2 (Source
ground return) to pin 5 of the IC. A sudden
increase in voltage will shut down the oscil-
lator.
6) Pin 4 of the IC, the oscillator’s DC supply
input, also provides Over Voltage Protection.
If the voltage at pin 4 exceeds 20.5 volts the
oscillator shuts down.