5
DRAWMER
T
HREE
-S
UM
O
PERATOR’S
M
ANUAL
The Three-Sum unit will be supplied with a power cable suitable for domestic power outlets in your country. For your own
safety, it is important that you use this cable to connect to the mains supply earth. The cable must not be tampered with
or modified.
The power supply socket has an integral fuse drawer con-
taining the power fuse of the same value, to suit the mains
voltage for which the unit has been supplied. Removal of
the drawer is only possible with the power cord removed.
The fuse should never blow under normal operation. If the
fuse is suspected of having blown, then a fault will have
occurred and this fault condition should be inspected by a
qualified service engineer. When replacing the fuse, always
comply with the Safety Instructions.
If the unit is to be used with a mains input operating voltage
different to that for which the unit is supplied, the following
procedure must be carried out by a technically competent
person,
(see following diagrams)
fig.2
THREE-SUM REAR CONNECTOR WIRING
POWER CONNECTION
Fuse
fig.4
The Voltage Selector Switch
fig.3
The Location of the Fuse
Voltage
Selector
Switch
1: Disconnect the unit from the mains.
2: Using a number 1 size pozidrive screwdriver,
remove the eleven self -tapping screws that retain
the top cover. One screw is located in the top centre
of the front panel (next to the “PEAK LEVEL” text);
six screws are located on the top cover; and two
screws on either side.
3: Inside the unit slide the voltage change-over switch
(SW8)
until the correct (or nearest) mains input
voltage is visible on the switch actuator.
(see fig.4)
4: In the fuse draw change the fuse to suit the following
values:
For
230 V
olt operation alter the fuse to a similar type
rated at
T80mA.
For
115 V
olt operation alter the fuse to a similar type
rated at
T160mA
.
