Troubleshooting Charts:
VCO Failure
5-41
VCO Failure – Page 4
(UHF2)
Is power at
C3161
>-20dBm?
Take continuity
check of traces to
U702.
3
At Rx, is L701 high and
L702 low?
At Tx, is L701 low and
L702 high?
Is power at U3001 input
Tx: C3112
Rx: C3102
>-20dBm?
Check continuity at
L701 and L702.
Fault found?
Check parts around
U3001. If OK,
replace U3001.
Replace suspected
components.
Replace U702.
Control voltage
at R705
0.3<Vdc<10.6?
Is Vdc = 4.55V at pin
3 of Q3123 during
Rx and at Q3156
during Tx?
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.
No
Yes
Yes
Yes
Yes
No
Yes
No
No
Yes
No
No
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Yes
No
Yes
For Tx: Check and visual inspect D3135 -
D3138, C3140, C3141, C3143, C3147,
L3139, L3145.
For Rx: Check and visual inspect D3102 -
D3105, C3107, C3108, C3110, C3113,
L3106, L3112.
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: ......