SM-6495 - Ansaldo STS

General Maintenance and Troubleshooting7. With the crossing operating and the gate arm going up, make certain that the voltage does not fallbelow 11VDC on 12-volt systems and 21 VDC on 24-volt systems.8. Place the voltmeter on the AC scale. The voltmeter must block the DC voltage. For somevoltmeters, such as most analogs, it may be necessary to place a 0.1μF to 1μF capacitor in serieswith the meter. An oscilloscope can be used as an alternative.9. Again, with the crossing operating and the gate arm going up, check that the voltmeter does notread more than 3 VAC (this is checking the AC).2.3.2. Wiring Diagram for 12-Volt SystemsConnect the wires to the Terminal Board as shown in Figure 2-2 or Figure 2-3 for 12-volt systems.NOTEThe wiring diagrams in Figure 2-2 and Figure 2-3, have the spare,unused terminals on the lower terminal block. Gate mechanismsproduced prior to July 5, 2004, have wiring arrangements that had thespare/unused terminals on the upper block.2.3.3. Wiring Diagram for 24-Volt SystemsConnect the wires to the Terminal Board as shown in Figure 2-4 for 24-volt systems.NOTEThe wiring diagram in Figure 2-4 has the spare, unused terminals on thelower terminal block. Gate mechanisms produced prior to July 5, 2004,have wiring arrangements that had the spare/unused terminals on theupper block.2.3.4. Wiring Diagram for 3-Wire Control 12-Volt SystemsConnect the wires to the Terminal Board as shown in Figure 2-5 for 3-wire control 12-volt systemsNOTEThe wiring diagram in Figure 2-5 has the spare, unused terminals on thelower terminal block. Gate mechanisms produced prior to July 5, 2004,have wiring arrangements that had the spare/unused terminals on theupper block.SM 6495, Rev. 7, December 2008 2-7