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Troubleshooting Flow Chart for Receiver, for models with PCB 8486473Z04 (Sheet 1 of 2)
3-3
2.0
Troubleshooting Flow Chart for Receiver, for models with PCB
8486473Z04 (Sheet 1 of 2)
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at pin
8 of U3220?
Check Controller
(in the case of no audio)
OR ELSE go to “B”
Yes
No
Spray or inject 44.85MHz
into XTAL Filter Y3200
Audio heard?
B
Yes
No
Check 2nd LO
(44.395MHz) at C3274
LO Present?
B
Yes
Voltages
ok?
Biasing ok?
Check circuitry
around U3220.
Replace U3220
if defect
No
No
A
Yes
Check Q3200 bias
for faults.
Replace Q3200.
Go to B
Yes
No
Check voltages on
U3220
Check circuitry
around Y3202.
Replace Y3202
if defect
Summary of Contents for GP1280 Series
Page 1: ...Professional Radio GP Series VHF 136 174MHz Service Information Issue November 2004 ...
Page 24: ...2 14 THEORY OF OPERATION ...
Page 34: ...3 10 TROUBLESHOOTING CHARTS ...
Page 38: ...4 4 VHF PCB SCHEMATICS PARTS LISTS ...
Page 50: ...4 16 VHF PCB 8486062B12 Parts List Intentionally Left Blank ...
Page 54: ...4 20 VHF PCB 8486101B09 Schematics GP1280 Intentionally Left Blank ...
Page 64: ...4 30 VHF PCB 8486062B14 Parts List Intentionally Left Blank ...
Page 108: ...4 74 VHF PCB 8486473Z04 Radio Parts List Intentionally Left Blank ...