Technical description
4-2 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
If the DC supply voltage exceeds 16 V, zener diode V2 conducts causing V3 to
also conduct and switch off V4, thus preventing K8 from energising.
Diode D7 prevents relay K8 from operating if the DC supply is reverse polarised.
The power input circuit is protected from high voltage transients by Voltage
Dependent Resistor (VDR) R8.
Power off
If the On/Off button on the control panel is pressed [1 04-02974] when the
transceiver is operational, a scanning active low pulse from the microprocessor
IC2 pin 11 is applied to the input port of IC1. The interrupt line (pin 13)
momentarily goes low, indicating to the microprocessor IC2 to read the input ports
of IC1 and to switch off the transceiver.
The switch off command is sent from IC2 (pins 22 and 23) via the external I
2
C
bus to microprocessor IC101 on the Microprocessor and Audio PCB [1
04-02976 Sheet 1] pins 22 and 23.
Microprocessor IC101 outputs data on the local I
2
C bus to IC109 pins 23 and 24,
latching pin 5 on the PWR OFF line low. The OFF coil of latching relay K201
(see Sheet 2) energises, opening K201 contacts and releasing the power relay K8
on the PA assembly, thus switching off the transceiver.
Supply voltages
The supply voltages on the Display Panel PCB [1 04-02974] are shown in
Table 4-11.
Table 4 -11: Display Panel PCB supply voltages
Supply Description Regulator
"A" rail unregulated battery supply
"B" rail 10 V regulated supply IC9
+5 V 5 V regulated supply IC11
-7 V -7 V from charge pump supply IC7
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