Motorola ASTRO SPECTRA Service Manual page 138

9-10
Symptom
No Receiver
Audio or
Receive Does
Not Unsquelch
Audio
Distorted or
Not Loud
Enough
February 3, 2003
Table 9-6. Receiver Troubleshooting Chart (Continued)
Possible Cause
Audio PA Circuit
Regulators (Command
Board)
RF Board
VOCON Board
Codeplug
VOCON Board
Synthesizer Not On
Frequency/Working
Command Board
Basic Troubleshooting: Receiver Troubleshooting
Correction or Test (Measurements Taken
at Room Temperature)
1. Check codeplug to ensure correct frequency
and signaling (PL, DPL) is enabled (use the
appropriate radio programming software).
2. Check continuity of F500 on command board.
If open, check for speaker leads shorted to
ground. Replace, if necessary.
Check for 9.6 Vdc on pin 10 of J500 and +5V on
pin 1 of J500.
If not there, then check for A+ at pin 30 of P502
and SWB+ at pin 31 of P502.
If OK, replace the command board.
Replace RF board.
Replace VOCON board.
Is the codeplug properly configured including
bandwidth and signaling?
Is there >100 mVrms audio on pin 40 of P501?
If not, replace VOCON board.
Check synthesizer frequency across pins 14 and
16 of P503.
If off by more than 250Hz, then go to the
Synthesizer Troubleshooting Chart on
Replace command board.
page 9-12
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6881076C20-E