Troubleshooting Flow Chart For Receiver (Sheet 1 Of 2) - Motorola 6864115B62-C Detailed Service Manual

3-2
2.0 Troubleshooting Flow Chart for Receiver
(Sheet 1 of 2)
B
B
Check
circuitry
around U1103.
Replace U1103
if defect.
Check circuitry
around U1103.
Replace U1103
if defect.
START
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
Audio
at pin 8 of
U1103
?
No
Spray or inject 10.7MHz
into XTAL Filter FL1102.
Yes
Audio
heard
?
No
Check 2nd LO
(10.245MHz) at C1129.
Yes
LO
present
No
Check
No
voltages on
U1103.
OK?
Yes
Check circuitry around Y1101.
Replace Y1101 if defect.
Check Controller (in the case of no audio).
Yes
Replace Q1106.
Low Band TROUBLESHOOTING CHARTS
Or else go to "B"
A
Check Q1106 bias
for faults.
Biasing
OK
No
Yes
Go to B