Maintenance
HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual 5-13
q If DC is measured at any of the points indicated:
Check the base-emitter voltage of switching transistors V3 and V7. If it
measures 0.5 V or more, check that the output voltages of NAND gates
IC6/C and IC6/D are correct as shown on the circuit diagram.
Check if DC can be measured on the mixer IC5 pins 4 and 11. If so, then
unsolder and lift one side of resistor R35. Check if the voltage still appears
at the collector of transistor V3. If so, suspect collector-emitter leakage of
the transistor and replace the transistor. If DC still remains on pins 4 and 11
of the mixer, replace IC5.
Check if DC can be measured on mixer IC8 pins 4 and 11. If so, then
unsolder and lift one side of resistor R46. If the DC still remains on pins 4
and 11, replace IC8. If the voltage is only on the collector of V7 (with R46
lifted), apply a short circuit between IC202 pin 5 and ground. If the voltage
goes from the collector of V7, then replace modulator IC202. If the voltage
remains on the collector with pin 5 shorted, then replace V7 (collector-
emitter leakage).
No transmit
q Check the supply voltages are correct (see page 5-11, Voltage
measurements).
q Apply an audio signal of about 1 kHz at a level of 10 mV RMS to the
microphone input connector J3 pin 2 and ground pin 3 on the control
panel/head. Select Transmit mode (pin 5 to ground). With the aid of an
oscilloscope, trace the audio, IF and RF signals through the transmit path.
Check that the measured levels correspond approximately to the levels
shown on the circuit diagrams. A reduction of signal or complete failure at
any of the check points should indicate the approximate location of the fault.
Unlocked synthesiser
If VCO1 or VCO2 lose lock (H101 and/or H102 illuminate on the Microprocessor
and Audio PCB [1 04-02976]):
q Check the 26 V supply is present and connected to the oscillator VCO1 (V8
and V9) and the control amplifier V11 and V13 [1 04-02972] or V12 and
V18 [1 04-03135].
If VCO2 has failed, check that 18 V is present at the control amplifier
IC14/A pin 8 [1 04-02972 only].
q Check that VCO1 and VCO2 are oscillating.
The frequencies at TP4 (VCO1) and TP8 (VCO2) should be within the
range indicated on the diagram.
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