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Troubleshooting Charts
5-23
6881076C25-E
September 5, 2008
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
Yes
No
Yes
Yes
Yes
No
No
No
No
Yes
Yes
No
Yes
No
Yes
No
Yes
No
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No
No
Yes
Summary of Contents for ASTRO Digital Spectra
Page 2: ......
Page 6: ...September 5 2008 6881076C25 E iv Document History Notes ...
Page 20: ...xviii List of Tables September 5 2008 6881076C25 E Notes ...
Page 24: ...September 5 2008 6881076C25 E xxii CommercialWarranty Notes ...
Page 48: ...September 5 2008 6881076C25 E xlvi Model Numbering Charts and Specifications Notes ...
Page 142: ...September 5 2008 6881076C25 E 3 82 Theory of Operation Power Amplifiers Notes ...
Page 434: ...September 5 2008 6881076C25 E Glossary 10 Notes ...
Page 440: ...Index 6 September 5 2008 6881076C25 E Notes ...
Page 441: ......