Motorola CP040

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