Motorola GM640 Service Information - Page 23
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1.0
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)
B
B
Check circuitry
around U3101.
Replace
U3101 if defect
TROUBLESHOOTING CHARTS
START
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
Audio at
Yes
pin 8 of
U3101 ?
No
Spray or inject 44.85MHz
into XTAL Filter FL3101
Yes
Audio heard ?
No
Check 2nd LO
(44.395MHz) at C3135
Yes
LO present ?
No
Check voltages on
U3101
No
Voltages
OK?
Check Controller
(in the case of no audio)
OR ELSE go to "B"
Replace Q3102
Check circuitry around Y3101 Re-
Yes
Chapter 3
A
Check Q3102 bias
for faults
No
Biasing OK ?
Yes
Go to B
place Y3101 if defect