Product Manual

Appendix A
AC Supply Voltage
Introduction
Before connecting the instrument to an ac outlet, check that the instrument operating
voltage marked on the rear panel is correct for the local supply.
Warning
To avoid the possibility of electric shock, always ensure the
instrument is disconnected from the ac supply before opening
the case.
Changing the Supply Voltage Setting
If it is necessary to change the operating voltage, proceed as follows:
Single channel instrument model 291
1. Disconnect the instrument from all voltage sources.
2. Remove the screws which retain the top cover and lift off the cover.
3. Change the transformer connections following the diagram below.
To change the connection, cut the brown wire from the switch at the switch end of
the crimped butt connector; make safe the exposed end of the connector.
Strip 6mm of insulation from the end of the cut brown wire; fit into the connector for
the new supply voltage and crimp.
Check that the connection is mechanically secure and that there are no loose strands.
for 230V operation connect the brown transformer wire to the brown wire from the
switch
for 115V operation connect the red transformer wire to the brown wire from the switch
for 100V operation connect the black transformer wire to the brown wire from the switch
4. Refit the cover and the secure it with the screws.
A-1