5-38
Troubleshooting Charts:
RX RF Failure
RX RF Failure – Page 9
(For reference only)
U601-38(Vdc)
TP601 (MHz) Fvco
0.00 102.70
1.33 107.40
3.89 111.90
5.00 112.75
11
Measure control
voltage at U601
pin 38
Fvco too low?
7/800 & UHF1/UHF2:
<107.4 MHz
U601 Pin 38
= 5 Vdc?
U601 Pin38 = 0
Vdc?
10
10
Remove Abacus
2nd LO shield,
SH17 and inspect
second LO VCO.
Visual
examination
Repair
defects
Replace
Varactor
VR602
No
No
Yes
No
Yes
Yes
No
Yes
12
Remove IF filter shield,
SH10. Check IF filter and
LC matching networks.
Visual
inspection
OK?
Repair
Defects
Replace IF
filter, FL502.
No
Yes
Note:
RF Test frequency used:
VHF: 154.275MHz
UHF1: 424.975MHz
UHF2: 485.075MHz
700: 769.0625MHz
800: 860.0625MHz
Measured with a High Frequency Probe for
relative comparisons and troubleshooting only.
Actual S21 gain or loss may differ if the
test point is not 50 ohms.
Summary of Contents for APX 2000
Page 1: ...APXTM TWO WAY RADIOS APX 1000 APX 2000 APX 4000 APX 4000Li DETAILED SERVICE MANUAL ...
Page 4: ......
Page 6: ...iv Document History Notes ...
Page 8: ...Notes vi Commercial Warranty ...
Page 10: ...Notes ...
Page 22: ...xiv List of Figures Notes ...
Page 226: ...6 64 Troubleshooting Waveforms LF CW on Spectrum Analyzer Notes ...
Page 688: ...Index 4 Index Notes ...
Page 690: ...ii Notes ...
Page 700: ...xvi List of Figures Notes ...
Page 806: ...5 50 Troubleshooting Charts PA Failure Notes ...
Page 1008: ...8 178 Schematics Boards Overlays and Parts Lists Transceiver RF Boards UHF2 84012621001 Notes ...
Page 1062: ...8 234 Schematics Boards Overlays and Parts Lists Keypad Board M2 and M3 PC000261A01 Notes ...
Page 1064: ...ii Notes ...
Page 1068: ...Notes A 4 EMEA Warranty Service and Technical Support Further Assistance From Motorola ...
Page 1090: ...Glossary 10 Glossary Notes ...
Page 1094: ...Index 4 Index Notes ...
Page 1095: ......