Motorola HT Series Service Manual

Maintenance: 900 MHz Troubleshooting Charts 8-55
8.17.6 Troubleshooting Flow Chart for Synthesizer
5V
at pin 6 of
D201.
Is
information
from µP U409
correct?
Is U201 Pin 28
at 4.6 VDC?
Is U201 Pin 47
AT = 1 3 VD C
Start
Visual
check of the
Board OK?
Correct
Problem.
Check 5V
Regulator.
+5V at U201
Pin’s
13 & 30?
Is 16.8MHz
Signal at
U201 Pin 19?
Check Y201, C235,
C237, C236, CR203
& R211.
Are the wave-
forms
at Pin’s 14
&15 of U201
rectangular?
Check
L200.
Replace U201.
Remove
Shorts.
Is there a short
between Pin 47 and
Pins 14 & 15 of
U201?
Replace or
resolder
defective
components.
Is RF level at
U201 Pin 32
as indicated?
Are
C226, R209,
R210, L204, C231,
C801, C802, C803,
C804, C805, C225,
C218, R216, and
R217 OK?
Replace U201.
If L203, C227 & C228
are OK, then see VCO
troubleshooting chart.
Are Waveforms
at Pins 14 & 15
triangular?
Do
Pins 7,8 & 9
of U201 toggle
when channel is
changed?
Check programming
lines between U409
and U201 Pins 7,8 & 9.
Replace U201
Check uP U409
Troubleshooting
Chart.
NO
YES
NO
YES
NO
YES
NO
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
Check D201, D202,
C244, C245, C246 &
C247.
3.3V at U201
pins 5, 20, 34
& 36.
Check U24
L202.
Is
16.8MHz
signal at
U201 pin
23?
Replace
U201.
YES
NO
NO
YES
NO
YES

Motorola HT Series Specifications

General

Battery Type	Li-Ion
Waterproof	IP54
Operating Temperature	-30°C to +60°C
Frequency Range	VHF: 136-174 MHz
Number of Channels	16