Motorola Commercial Series Service Information - Page 22

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Motorola Commercial Series Service Information
3-6
4.0

Troubleshooting Table for Board and IC Signals

IC Designator
U51
IFIC
U52
BW Select Switch
Pin
Pin Function
1
RF input 44.85 MHz
2
RF input decoupling
3
2nd LO osc output
4
2nd LO osc input
5
RSSI output
6
Vcc
7
Audio feedback
8
Audio output
9
RSSI feedback
10
Quad detector input
11
Limiter output
12
Limiter decoupling 2
13
Limiter decoupling 1
14
Limiter input
15
Ground
16
IF amp output
17
IF amp decoupling 2
18
IF amp input
19
IF amp decoupling 1
20
2nd mixer output
1
Inverter 1 input
2
Inverter 2 output
3
Inverter 3 input (NU)
4
Ground
5
Inverter 3 output (NU)
6
Inverter 2 input
7
Inverter 1 output
8
Vcc
TROUBLESHOOTING TABLES
DC Voltage
Comments (Condition)
1.20
1.20
4.02
4.60
0.74
(no received signal)
4.70
0.89
1.44
DEMOD to stage U510
0.74
(no received signal)
2.22
1.25
1.30
1.30
1.28
GND
1.22
1.26
1.26
1.26
3.09
0
(25 kHz mode)
0
(25 kHz mode)
GND
GND
4.96
3.00
(25 kHz mode)
4.95
(25 kHz mode)
4.96