Motorola ASTRO SPECTRA Service Manual

February 3, 2003 6881076C20-E
9-8 Basic Troubleshooting: Transmitter Troubleshooting
NOTE:The P501 pins can be probed on the extender cable (see the P501 Extender Cable
diagram on
page 10-6).
Can’t Set
Compensation
VOCON Board Vary deviation and compensation controls
from maximum to minimum.
With the low frequency source active
(using the appropriate radio programming
software–see
Chapter 6: Radio
Alignment Procedure
) voltage or pin 48
of P501 should vary from <100 mVrms to
>3 mVrms.
With the high frequency source active,
voltage on pin 49 of P501 (ac coupled)
should vary from <100 mVrms to >3
mVrms.
Command Board 1. All modulation testing should be done
with the radio keyed and 1 Vrms on the
mic high line of the microphone.
Check that normal voice deviation is OK.
Otherwise, go to No Modulation or Bad
Microphone Sensitivity.
2. Set deviation and compensation
controls to maximum.
Voltage on pin 17 of J500 should be > 3 V
p-p.
Voltage @ pin 11 of J500 should be >3 V
p-p.
If not, replace the command board.
RF Board If maximum deviation can be set to > 5.0
kHz, but compensation cannot be set,
then replace the RF board.
Otherwise, replace the VCO board.
Table 9-5. Transmitter Troubleshooting Chart (Continued)
Symptom Possible Cause
Correction or Test (Measurements
Taken at Room Temperature)

Motorola ASTRO SPECTRA Specifications

General

Frequency Range	136-174 MHz, 403-470 MHz
Number of Channels	Up to 255
Channel Spacing	12.5 kHz, 20 kHz, 25 kHz
Modulation	FM
Operating Temperature	-22°F to +140°F (-30°C to +60°C)