Motorola EP450

November 24, 2003 HKLN4216A
5-16 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals
Notes:
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)
7Ground 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 (0 V).
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 5-4. Troubleshooting Table for Board and IC Signals (Continued)
IC Designator Pin Pin Function DC Voltage Comments (Condition)