Technical Manual
Table Of Contents
- Vocoder and Controller Boards Detailed Theory of Operation
- Introduction to This Section
- General
- Vocoder Board
- Controller Board
- Switching Regulator
- RX Signal Path
- TX Signal Path
- Controller Bootstrap and Asynchronous Buses
- Vocoder Bootstrap
- SPI Bus Interface
- Universal Connector and Option Selects
- Keypad and Display Module
- Controls and Control Top Flex
- Controller Memory Map
- Vocoder Memory Map
- MCU System Clock
- DSP System Clock
- Radio Power-Up/ Power-Down Sequence
- Notes
- Secure Modules
- Disassembly/Reassembly Procedures
- Troubleshooting Procedures
- Troubleshooting Charts
- Troubleshooting Waveforms
- Troubleshooting Diagrams
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
ยตC.
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?