Troubleshooting Flow Chart For Receiver - Motorola GTX 2000 Service Manual

Troubleshooting
Troubleshooting Charts
Start
Very low or no 12
dB SINAD
Noise at spkr
when radio is
unsquÕd?
YES
Is 1st LO
3dBM?
YES
Inject on channel
signal at RF port
of mixer U50
Is 12 dB SINAD
-112 dBm?
NO
Inject signal at
IF Port of mixer
U50 at 45.1 MHz
Is 12 dBS -120
dBm?
NO
Inject a 45.1
MHz signal at
C59
YES
Is 12 dBS -112
dBm?
NO
1
Troubleshooting Flow Chart
for Receiver
4-2
Check IFIC
U51 (see
below)
NO
Noise at pin 23
of IFIC U51?
YES
Check ASFIC
NO
Check
VCO/Synth
Inject on Channel
YES
signal at pin 1 of
Front End filter
FL1
YES
Is 12 dBS -117
Check
harmonic
filter and
antenna path
YES
Check mixer
components
NO
Is Q51 biased
correctely?
YES
Check XTAL filters
Y51A & Y51B
GTX/GTX LTR/LTS 2000 Portable Radios Service Ma nual
1
Is 2nd LO on
freq?
YES
Check VDC of
NO
all IFIC pins
Are voltages on
pins OK?
NO
Check external
components
connected to IFIC. If
OK, replace U51
NO
dBm?
3.7VDC at
junction of R3
and L3?
YES
Check Q1
and external
components
Check 5R
and IF amp
components
68P02945C75-A
Are VDC of
NO
pins 7,9, and
10 of IFIC
OK?
YES
Check 2nd LO
XTAL and
components
YES
Check IFIC
(see below)
Check external
components
connected to IFIC
NO
Check 5R
and Q405
NO
June 1999