10-22
Chart 20. Volume Set Error
Synopsis
This chart relates to a failure
in volume set knob. Basic
Failure modes are as follows:
1) Failure in control top/ptt
flex circuit.
2) Bad connection.
3) Defective volume pot.
4) Defective A/D port in host
C.
5) Problem in receive audio
circuit.
Volume Set
Error
Using voltmeter,
measure voltage at
U701-25 while
turning volume pot
from min to max.
Voltage should vary
from 0 to 5VDC.
Voltage
functional?
Verify connections
and control top/ptt
flex connections.
No
Yes
Measure resistance
from pin 2 of SI
(controls flex assembly)
to GND while moving
volume pot through
range; value should
vary from 50K to 0K.
Volume
pot OK?
Replace
front cover (housing)
assembly.
No
Yes
MAEPF-26034-O
Replace U701.
Verify operation of
volume knob per
"Button Check" flow
chart C.18.
Refer to "No
Receive Audio"
flow chart C.27.
Yes
No
Volume checks
OK?
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