User's Manual

Chapter 5 Troubleshooting Charts
This section contains detailed troubleshooting flowcharts. These charts 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.
5.1 List of Troubleshooting Charts
Most troubleshooting charts (see Table 5-1) 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.
Table 5-1. Troubleshooting Charts List
Chart Title
Page
Number
Main Troubleshooting Flowchart 5-2
Power-Up Failure 5-3
DC Supply Failure 5-5
Display Failure (NNTN4563, NNTN4819, & NNTN4717
VOCON Kits)
5-8
Display Failure (NTN9564) 5-11
Volume Set Error 5-14
Channel/Zone Select Error 5-15
Button Test 5-16
Top/Side Button Test 5-17
VCO TX/RX Unlock 5-18
VOCON TX Audio 5-19
VOCON RX Audio 5-21
RX RF
5-23
TX RF (VHF) 5-28
TX RF (UHF R1/700-800 MHz) 5-31
Keyload Failure 5-34
Secure Hardware Failure 5-35