Motorola ASTRO Digital Spectra Service Manual

Troubleshooting Charts 5-23
6881076C25-D October 28, 2002
Chart C.29 ASTRO Spectra Plus VOCON TX Modulation Failure Sheet 3 of 4
Inspect U501
Repair U501
B
D
C
OK?
Is problem with
Keyed9.4_EN or
TXPA_EN
Keyed9.4_EN
TXPA_EN Check for GND
at J501-14 Present?
Defective PCB
Check for 5V at
U501-5
Present?Present?
Present?
Defective PCB
Check for 3V at
U501-15
Replace U501
Check for GND
at U501-11
Present? Replace U501
Check Patriot supplies
L300 - T1 - 3.0V
L301 - T2 - 1.8V
Repair regular
circuit
OK?
OK?
Check Patriot clocks
C326 - T1 - 16.8 MHz
R428 - T2 32 kHz
Repair proper clock
circuit
Inspect and repair
Patriot IC - U300
Inspect U402, also check 3V
at pin6 and GND at pin 15
OK?
Repair U402
Inspect U404, also check 5V
at pin8 and GND at pin 4
OK?
OK?
OK?
Repair U404
Repair U400, U401
Inspect U400, U401, also
check 3V at pin8 and GND
at pin 4
Measure waveform at TP404,
should match Figure 6-17
Amplitude of
waveform
may vary
Make sure that R401, R408
are placed and values are
correct
Continued on
next page
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Motorola ASTRO Digital Spectra Specifications

General

Brand	Motorola
Model	ASTRO Digital Spectra
Category	Radio
Language	English