Service manual

GPH-CMD VHF Radio Maintenance
BK RADIO Page 5-15
5.6 TROUBLESHOOTING
Radio Will Not Transmit
Red LED Does Not Light
-Invalid TX frequency programmed
-Weak battery
-VCO TX bandshift circuit failing
-Open PTT path
-Broken PTT switch
Radio Will Not Turn On -Exhausted battery
-Open fuse
-Broken ON/OFF switch
-Failing 5-volt regulator
-Improper information in EEPROM
Radio Will Not Unmute -Invalid RX frequency programmed
-Internal squelch trimmer adjusted improperly
-CAR PRES signal to microprocessor shorted or
open
-Audio amplifier failing
-DISC AUDIO path open or shorted
-RX AUDIO path open or shorted
Transmit Power Below Specification -Software power adjustment incorrect
-RF side connector jack failing
-Harmonic filter failing
-Power amplifier failing
-Power control circuit failing
-Antenna switch failing
-VCO buffer failing
Code Guard Signal Not Being
Transmitted
-No Code Guard signal programmed on transmit
channel
Poor Battery Life -Weak or defective battery
-Transmitter power adjusted too high
-Audio amplifier not switching off
Radio Unmutes With No Carrier Present
When In Preset Condition
-Internal squelch trimmer adjusted improperly
-Open or shorted CAR PRES signal
Sensitivity Does Not Meet Specification -Front-end filters misaligned or failing
-Software front-end tuning adjusted improperly
-RF preamplifier failing
-IF filter or amplifier failing
-VCO buffer failing
Receiver Distortion Out Of Specification -IF transformers mistuned
-Audio amplifier failing
Low or No Transmitter Audio Modulation -Transmit Analog or Digital Deviation misadjusted
-Microphone failing
-VCO modulation circuit failing