Troubleshooting Charts; Troubleshooting Flow Chart For Receiver - Motorola GP2000 Service Manual

Troubleshooting charts

6.0 Troubleshooting charts
Start
Very low or no 12
dB SINAD
Noise at spkr
when radio is
unsquÕd?
YES
Is 1st LO at
TP302 >0
dBm?
YES
Inject on channel
signal at RF port,
L706 pin 6
Is 12 dB SINAD
-110 dBm?
NO
Inject 45.1
MHz signal at
R459 Terminal
YES
Is 12 dBS -117
dBm?
NO
Inject a 45.1
MHz signal at
C501
YES
Is 12 dBS -110
dBm?
NO
1
Check IFIC
Q506 (see
NO
Noise at pin 9
of IFIC Q506?
YES
Check Q702
NO
Check
VCO/Synth
YES Inject on
channel signal
at C407
YES
Is 12 dBS -116
Check
harmonic
filter and
antenna path
Check mixer,
Q407
Is Q506 biased
correctly?
YES
Check XTAL
filter X501
1
Is 2nd LO on
below)
freq?
NO
Check VDC of
all IFIC pins
Are voltages on
pins OK?
Check external
components
connected to IFIC. If
OK, replace Q506
NO
dBm?
Is Q404 biased
properly?
Check 2-pole and
RF BPF
components
NO
Check +5vRX
and IF amp
components
NO
Are VDC of
pin 4 and
10 of IFIC
YES
YES
Check 2nd LO
XTAL and
components
YES
NO
Check external
components
connected to IFIC
NO
YES
Check +5vRX and
Q404 bias circuitry
Troubleshooting Flow Chart for
Section 7 -27
NO
OK?
Check IFIC
(see below)
Receiver