Motorola EP450 Service Manual page 107

Vhf 146-174 mhz uhf 403-440 mhz uhf 438-470 mhz uhf 465-495 mhz
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10-14
Table 10-4. Troubleshooting Table for Board and IC Signals (Continued)
IC Designator
Pin
U451
ASFIC_CMP
November 24, 2003
UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals
Pin Function
14
GCB1 general purpose output
15
GCB0 general purpose output
16
Squelch channel activity output
17
Squelch detect digital output
18
PL/low speed data I/O
19
High speed data I/O
20
Chip select
21
Serial clock input
22
Serial data input
23
Ground for clock synthesizer
24
Loop filter cap for clock syn
25
PLCAP2 for LS integrator
26
Not used
27
Vdd for clock synthesizer
28
Clock synthesizer output
29
1200 Hz ref for MDC decode
30
GNDDO
31
Ground for digital circuits
32
Vdd for analog switches
33
Vdd for digital circuits
34
16.8 MHz master clock input
35
GCB3 general purpose output
36
TX audio return from option
37
GCB4 general purpose output
38
GCB5 general purpose output
39
RX audio send to option
40
Modulation output
41
RX audio out to power amp
42
Flat TX audio return from option
43
RX audio return to option
44
Flat TX audio send to option
45
Vdd for audio path I/O filters
46
Mic audio input
47
Ground for audio path I/O filters
48
Ext mic audio input (not used)
DC Voltage
Comments (Condition)
0
3.00
BW select (25 kHz mode)
0
To U401-84
0
To U401-83
1.50
3.00
3.23
From U401-2
0
3.23
GND
0.74
1.17
0
3.00
1.70
3.00
GND
GND
4.96
3.00
1.54
3.00
Internal MIC enable
0
0
0
1.48
1.50
To U201-10
1.51
0.20
1.50
1.50
3.00
1.50
GND
0
HKLN4216A

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