Lake Shore Model 642 Electromagnet Power Supply User’s Manual
7-2
Service
7.3
LINE VOLTAGE SELECTION
The Model 642 may be configured for four basic AC power configurations: 208 VAC, 230 VAC, 380 VAC and 415
VAC. Proper voltage selection must be made before connection to the power mains. Each configuration requires the
appropriate wiring within the power wiring access panel on the rear of the instrument. Nominal line voltages and
appropriate selections are shown in Table 7-1. See Section 3.3.1 for further details. See Figure 7-1 for general locations.
Figure 7-1. Model 642 Rear Panel (shown with wiring cover removed)
Use the following procedure to change the instrument line voltage.
WARNING:
To avoid potentially lethal shocks, turn off the power supply and disconnect it from AC power before
performing this procedure.
1. Identify the power wiring access panel on the rear of the Model 642.
2. Turn the front panel line power switch OFF (
O
).
3. Disconnect the power cable at the plug end for safety.
4. Remove the perimeter screws holding the power wiring access panel.
5. Observe the 4 voltage-selection wires held by the clear plastic wiring guide. See Figure 7-2.
6. Loosen the screw terminals presently holding the four wires.
7. Relocate the 4 wires (using the wiring guide) to the desired voltage position. Refer to Table 7-1.
8. Place the wires into the appropriate screw terminals and tighten.
9. Verify solid, tight screw connections to these four wires.
10. Replace the power wiring access panel using all perimeter screws.
11. Verify the voltage indicator in the window of the power wiring access panel.
