Motorola GP344 - Page 49

Troubleshooting Charts (includes Controller and Keypad) 2-7
U201 pin 2
at >3V in Tx
and <0.7V in
Rx
5V
at pin 6
of
CR201
Is information
from µP U409
correct?
Is U201 Pin
18
AT 4.54
VDC?
Is U201 Pin 47
AT = 13 VDC
Is U241 Pin 19
<0.7 VDC in RX &
>4.3 VDC in TX?
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 FL201,
C206, C207,
C208, CR203 &
R204
Are signals
at Pin’s 14 &
15 of U201?
Check
L202
Check Q260,
Q261 &
R260
Replace
U201
Remove
Shorts
Is there a short
between Pin 47
and
Pins 14 & 15 of
U201?
Replace or
resolder
necessary
components
Is RF level at
U201 Pin 32
>-30 dBm?
Are R231,R232,
R233,C231,C23
2 & C233 OK?
Replace
U201
If L261, C263 & C264
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
YES
NO
NO
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
Check CR201,
U210, U211,
C258, C259 &
C228
3.3V at
U201 pins
5, 20, 34 &
36
Check U248,
L201 & L202
Is
16.8MHz
signal at
U201 pin
23?
Replace
U201
YES
NO
NO
YES
NO
YES
Figure 2-6 Troubleshooting Flow Chart for Transmitter UHF1 and UHF2