Troubleshooting Table For Board And Ic Signals - Motorola CP140 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