Figure 4-1. Att-20 Test Circuit For Shunt Mode Application - Hitachi ATT-20 Installation, Operation, Troubleshooting

3. If the relay does energize, disconnect the resistor between terminals 3 and 5,
and disconnect the jumper between terminals 4 and 6. Measure the open circuit
voltage across terminals 3 and 4. The voltage should be equal to or greater than
2.3 Vrms. If this voltage should be equal to or greater than 2.3 Vrms, reconnect
the resistor between terminals 3 and 5, and reconnect the jumper between
terminals 4 and 6. Adjust the transmitter level so that it just energizes the relay.
Measure the voltage across terminals 5 and 6 (receiver input). This voltage
should be 70 mVrms + 14 mVrms. If not, replace the ATT-20 unit.
+
12V
BATTERY
_

Figure 4-1. ATT-20 Test Circuit for Shunt Mode Application

The tests performed in Section 4.4 verify proper operation of the ATT-20 unit in a shunt
mode application. If the track circuit installation still does not work properly, troubleshoot
the cabling, connections, and peripheral equipment associated with the track circuit.
Copyright 2019
ATT-20
1
3
5.0 OHM
2 4
SM 6299 Rev. 3, March 2019
ATT-20 Audio Track Transceiver
5 7
1.0
OHM
6 8
_
+
PN150B
RELAY
4-2