Motorola MDH65SDF9AA3AN Service Information - Page 31
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Troubleshooting Table for Board and IC Signals
IC Designator
U480
Dual Opamp
U490
Audio Power Amp
U510
Dual Opamp
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.
Pin
Pin Function
1
Unit 1 output
2
Unit 1 (-) input
3
Unit 1 (+) input
4
Ground
5
Unit 2 (+) input
6
Unit 2 (-) input
7
Unit 2 output
8
Vcc
1
Enable/shutdown
2
Bias reference
3
(+) input
4
(-) input
5
(-) output
6
Vcc
7
Ground
8
(+) output
1
Unit 1 output
2
Unit 1 (-) input
3
Unit 1 (+) input
4
Ground
5
Unit 2 (+) input
6
Unit 2 (-) input
7
Unit 2 output
8
Vcc
DC Voltage
Comments (Condition)
2.48
2.48
2.46
GND
0.28
0.29
0
4.96
0.12
(Unsquelched)
3.26
(Unsquelched)
3.26
(Unsquelched)
3.27
(Unsquelched)
3.25
(Unsquelched)
7.48
(Unsquelched)
GND
3.29
(Unsquelched)
1.75
1.56
1.55
GND
1.55
1.56
1.38
4.96
3-15