UHF2 Troubleshooting Tables: Troubleshooting Table for Board and IC Signals (UHF2) 6-5
(DTMF decoder) 2 IN- 1.6
3 GS 1.6
4Vref 1.6
8 OSC1 1.6 3.579545 MHz input
10 VSS 0
11 TOE 3.3
17 STD High At DTMF detecting
18 EST 3.3
19 ST/GT 3.3
20 VDD 3.3
FL701(VCTCXO) 1 VCON 1.9
2 GND 0
3 OSC out osc Generate the 12.8 MHz
4 VCC 5
Q206(N/S SW) E GND 0
B N/S SW 12.5 kHz: Low
C Collector 12.5 kHz: High
25 kHz: Low
Q304 E +5V 5 At RX Mode
B To Q305 collector Low
C RX_B+ 4.7
Q305 E GND 0 At RX Mode
B RX_EN High
C To Q304 base Low
Q503 E GND 0 At TX Mode
B TX_EN1 High
C To Q706 base Low
Q407 E +5V 5 At TX Mode
B To Q408 collector Low
C TXVB 4.7
Q408 E GND 0 At TX Mode
B TX_EN2 High
C To Q 40 7 Low
Table 6-4. Troubleshooting Table for Board and IC Signals (UHF2) (Continued)
IC Designator Pin Pin Function DC Voltage (V) Comments (Condition)
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