Motorola P100 Series Detailed Service Manual page 253

UHF1 Troubleshooting Tables: Troubleshooting Table for Board and IC Signals (UHF1)
Table 12-4. Troubleshooting Table for Board and IC Signals (UHF1) (Continued)
IC Designator Pin
(DTMF decoder) 2
3
4
8
10
11
17
18
19
20
FL701(VCTCXO) 1
2
3
4
Q206(N/S SW) E
B
C
Q304 E
B
C
Q305 E
B
C
Q503 E
B
C
Q407 E
B
C
Q408 E
B
C
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Pin Function
IN-
GS
Vref
OSC1
VSS
TOE
STD
EST
ST/GT
VDD
VCON
GND
OSC out
VCC
GND
N/S SW
Collector
+5V
To Q305 collector
RX_B+
GND
RX_EN
To Q304 base
GND
TX_EN1
To Q706 base
+5V
To Q408 collector
TXVB
GND
TX_EN2
To Q407
DC Voltage (V) Comments (Condition)
1.6
1.6
1.6
1.6 3.579545 MHz input
0
3.3
High At DTMF detecting
3.3
3.3
3.3
1.9
0
osc Generate the 12.8 MHz
5
0
12.5 kHz: Low
12.5 kHz: High
25 kHz: Low
5 At RX Mode
Low
4.7
0 At RX Mode
High
Low
0 At TX Mode
High
Low
5 At TX Mode
Low
4.7
0 At TX Mode
High
Low
12-5