Motorola CP 140, Detailed Service Manual

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Troubleshooting Tables for Board and IC Signals (includes Controller, DC Regulation and Audio) 2-7
U451
ASFIC_CMP
38 GCB5 general purpose output 0
39 RX audio send to option 1.48
40 Modulation output 1.50 To U201-10
41 RX audio out to power amp 1.51
42 Flat TX audio return from option 0.20
43 RX audio return to option 1.50
44 Flat TX audio send to option 1.50
45 Vdd for audio path I/O filters 3.00
46 Mic audio input 1.50
47 Ground for audio path I/O filters GND
48 Ext mic audio input (not used) 0
U480
Dual Opamp
1 Unit 1 output 2.48
2 Unit 1 (-) input 2.48
3 Unit 1 (+) input 2.46
4 Ground GND
5 Unit 2 (+) input 0.28
6 Unit 2 (-) input 0.29
7 Unit 2 output 0
8 Vcc 4.96
U490
Audio Power Amp
1 Enable/shutdown 0.12 (Unsquelched)
2 Bias reference 3.26 (Unsquelched)
3 (+) input 3.26 (Unsquelched)
4 (-) input 3.27 (Unsquelched)
5 (-) output 3.25 (Unsquelched)
6 Vcc 7.48 (Unsquelched)
7 Ground GND
8 (+) output 3.29 (Unsquelched)
U510
Dual Opamp
1 Unit 1 output 1.75
2 Unit 1 (-) input 1.56
3 Unit 1 (+) input 1.55
4 Ground GND
5 Unit 2 (+) input 1.55
6 Unit 2 (-) input 1.56
7 Unit 2 output 1.38
8 Vcc 4.96
1. All voltages are measured with a high-impedance digital voltmeter and expressed in volts DC relative to ground (0V).
2. Voltages are measured with a DC input voltage of 7.50 + .02 volts DC applied to the battery connector (J301).
3. All voltages are measured in the squelched receive mode, unless otherwise indicated.
4. Voltages are identical for VHF and UHF models unless otherwise indicated.
IC Designator Pin Pin Function DC Voltage Comments (Condition)