Troubleshooting Charts:
FGU Failure
5-37
5.11 FGU Failure
FGU Failure
Remove VCO
shield (SH15)
< 0.5Vdc at
pin 3 of Q767
Check logic in PA Section
TX Injection
Rx LO low Power?
Check power at input of
U738 pin 1
No fault found
Tx?
1.5Vdc at
L759?
Check 1.5Vdc supply
VCO Failure
< 1.5Vdc at
pin 2 of Q785
< 0.5Vdc at
pin 6 of Q785
Check parts around Q767. If OK,
replace Q767.
Check parts around Q785. If
OK, replace Q785.
Is power at
C817 >
- 20dBm
2.5Vdc at
U738 logic pin?
Is Power
> -20 dBm?
1.5Vdc at L739
< 0.5 Vdc at
pin 3 of Q745
Check 1.5Vdc supply.
Is power at
C740 >
-20dBm
Check parts around
Q756. If OK, replace
Q756.
Check parts around Q774.
If OK, replace Q774.
Yes
No
No
Check parts around
Q745. If OK, replace
Q745
Yes
Yes
Yes
Check parts around U738.
If OK, replace U738.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
2.5Vdc at
U738 logic pin?
Remove FGU shield (SH6)
Replace U702
No
No
No
No
No
No
No
Correct Tx/Rx
frequency?
Summary of Contents for Astro APX 3000
Page 1: ...APXTM TWO WAY RADIOS APX 3000 DETAILED SERVICE MANUAL ...
Page 2: ......
Page 4: ...Notes ...
Page 6: ...vi Document History Notes ...
Page 10: ...x Table of Contents Notes ...
Page 12: ...xii List of Tables Notes ...
Page 18: ...xviii List of Figures Notes ...
Page 22: ...xxii CommercialWarranty Notes ...
Page 46: ...3 20 Theory of Operation Main Board Notes ...
Page 84: ...3 58 Theory of Operation Bluetooth Notes ...
Page 208: ...6 64 Troubleshooting Waveforms LF CW on Spectrum Analyzer Notes ...
Page 222: ...7 14 Troubleshooting Tables List of Board and IC Signals Notes ...
Page 282: ...8 60 Schematics Boards Overlays and Parts Lists Main Board Block UHF1 84012513001_A Notes ...
Page 390: ...8 168 Schematics Boards Overlays and Parts Lists Main Board Block VHF 84012512001_A Notes ...
Page 456: ...9 8 Debugging Fixture Powering up Covert Board Notes ...
Page 468: ...Glossary 10 Glossary Notes ...
Page 472: ...Index 4 Index Notes ...
Page 473: ......