5-48
Troubleshooting Charts:
VCO Failure
VCO Failure – Page 3 (700/800 MHz)
Take continuity
check of traces to
U702.
2
Control voltage
at R705
0.3<Vdc<10.6?
At Tx 764-776MHz, Rx 851-870MHz, is
R3018 high?
or
At Tx 851-870MHz, Rx 764-776MHz, is
R3052 high?
or
At Tx 794-824MHz, is R3019 high?
At Tx 764-776MHz, Rx 851-870MHz, is
Vdc at Q3038 4.55V?
or
At Tx 851-870MHz, Rx 764-776MHz, is
Vdc at Q3062 4.55V?
or
At Tx 794-824MHz,
Vdc at Q3039 4.55V?
At Tx 764-776MHz, Rx 851-870MHz, check and visual
inspect VR3010, C3014, C3015, C3022, C3023, Y3020.
At Tx 851-870MHz, Rx 764-776MHz, check and visual
inspect VR3048, C3050, C3051, C3054, C3055, Y3053.
At Tx 794-824MHz, check and visual inspect VR3011,
C3016, C3017, C3024, C3025, Y3021.
Is Vdc at C742 5V,
Vdc at C726, C734,
C737 2.775V?
Is Vdc at Y701
pin 4 2.775V?
16.8MHz at pin
3 of Y701 and
C736?
16.8MHz at
L753?
10.8Vdc at pin2
of D723?
2.775Vdc at pin
4 of D722?
Check and visual
inspect U746 circuitry.
Fault found?
Check 2.775V and
5V supply.
Check 2.775V
supply.
Replace Y701
and/or C736.
Replace the
suspected
components.
Replace U702.
Check D722, D723,
C716, C717, C718,
C719.
Yes
No
No
No
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Yes
No
Yes
Yes
Yes
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: ......