Motorola EP450 - Page 108

HKLN4216A November 24, 2003
UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 10-15
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.
Table 10-4. Troubleshooting Table for Board and IC Signals (Continued)
IC Designator Pin Pin Function DC Voltage Comments (Condition)