Chapter 2
TROUBLESHOOTING TABLES
1.0
Troubleshooting Tables for Board and IC Signals (includes
Controller, DC Regulation and Audio)
This section contains detailed troubleshooting tables. These tables should be used as a guide in
determining the problem areas. They are not a substitute for knowledge of circuit operation and
astute troubleshooting techniques. It is advisable to refer to the related detailed circuit descriptions
in the theory of operation sections prior to troubleshooting a radio.
Most troubleshooting tables end up by pointing to an IC to replace. It is not always noted, but it is
good practice to verify supplies and grounds to the affected IC and to trace continuity to the
malfunctioning signal and related circuitry before replacing any IC. For instance, if a clock signal is
not available at a destination, continuity from the source IC should be checked before replacing the
source IC.
IC Designator
Pin
Pin Function
DC Voltage
Comments (Condition)
U310
5V Regulator
1
Vin
7.48
2
Ground
GND
3
Control input
7.48
4
Bypass capacitor
1.26
5
Vout
4.96
U320
3.3V Regulator
1
Ground
GND
2
Feedback
1.23
3
Tap (NU)
0
4
Vin
7.48
5
Vout
3.23
6
Sense (NU)
0
7
Error (reset output)
3.20
8
Shutdown input
7.48
U330
3V Regulator
1
Vin
7.48
2
Ground
GND
3
Control input
7.48
4
Bypass capacitor
1.26
5
Vout
3.00
Summary of Contents for CP 140
Page 1: ...Commercial Series CP140 CP160 CP180 Portable Radios Detailed Service Manual 6866550D20 O ...
Page 2: ...ii ...
Page 4: ...iv ...
Page 12: ...viii ...
Page 28: ...iv ...
Page 40: ...1 12 THEORY OF OPERATION ...
Page 48: ...2 8 TROUBLESHOOTING TABLES ...
Page 50: ...3 2 CONTROLLER KEYPAD SCHEMATICS ...
Page 58: ...3 10 Keypad Board Parts List 8466565A01 O ...
Page 62: ...iv ...
Page 66: ...1 4 MODEL CHART AND TECHNICAL SPECIFICATIONS ...
Page 90: ...3 16 TROUBLESHOOTING TABLES ...
Page 92: ...4 2 VHF PCB SCHEMATICS PARTS LISTS ...
Page 108: ...iv ...
Page 112: ...1 4 MODEL CHART AND TECHNICAL SPECIFICATIONS ...
Page 136: ...3 16 TROUBLESHOOTING TABLES ...
Page 138: ...4 2 UHF1 PCB SCHEMATICS PARTS LISTS ...
Page 154: ...iv ...
Page 158: ...1 4 MODEL CHART AND TECHNICAL SPECIFICATIONS ...
Page 182: ...3 16 TROUBLESHOOTING TABLES ...
Page 184: ...4 2 UHF2 PCB SCHEMATICS PARTS LISTS ...
Page 200: ...iv ...
Page 204: ...1 4 MODEL CHART AND TECHNICAL SPECIFICATIONS ...
Page 228: ...3 16 TROUBLESHOOTING TABLES ...