Series Mode Checks; Figure 4-2. Att-20 Test Circuit For Series Mode Application - Hitachi ATT-20 Installation, Operation, Troubleshooting

4.5. Series Mode Checks

Proceed as follows to perform a series mode check:
1. Connect the ATT-20 as shown in Figure 4-2.
2. Turn the RELAY VOLTS potentiometer fully clockwise. If the relay energizes,
proceed to step 3. If the relay does not energize, check the relay connections for
proper polarity and open circuits. If the relay connections are good, replace the
ATT-20 with a unit of the same frequency and then repeat steps 1 and 2. If the
relay still does not energize, replace the relay with another
coil (STS USA Part No. N322500-701).
3. If the relay energizes, 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. This voltage should be greater than or equal to
0.4 Vrms. Replace the ATT-20 if the open circuit voltage is less than 0.4 Vrms. If
the voltage is greater than or equal to 0.4 Vrms, reconnect the resistor between
terminals 3 and 5, and reconnect the jumper between terminals 4 and 6. Adjust
the transmitter level to just energize 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.
The tests performed in Section 4.5 verify proper operation of the ATT-20 unit in a series
mode application. If the track circuit installation still does not work properly, troubleshoot
the cabling, connections, and peripheral equipment associated with the track circuit.
+
12V
BATTERY
_

Figure 4-2. ATT-20 Test Circuit for Series Mode Application

Copyright 2019
ATT-20
1
3
1.0 OHM
2 4
SM 6299 Rev. 3, March 2019
ATT-20 Audio Track Transceiver
PN-150B,
5 7
6 8
_
400 ohm
+
PN150B
RELAY
4-3