Instructions

11
4.5 Fuses
4.5.1 Current Range Fuses
The unit is protected by two 10A fuses that protect the unit against currents that exceed 20A.
This is primarily as a protection against high power sources with a current capability of >20A
being connected to the load with reverse polarity.
The replacement fuse must be a 10x38mm 10A 1kVdc rated HRC fuse. To replace a fuse:
1. Disconnect the instrument from all voltage sources.
2. Remove the screws retaining the fan guard.
3. Replace the fuse with one of identical specification and size.
4. Refit the fan guard securely.
4.5.2 Internal AC Power Fuse
The AC supply transformers on the PSU PCB is protected against an internal fault by a non-
resettable thermal fuse. To avoid the thermal fuse being accidentally tripped by connecting to a
230V supply when the instrument set for 115V operation, a standard 500mA (T) 250V fuse is
fitted in position FS6 on the PSU PCB. Should this fuse need replacing, following such an event,
remove the case upper and replace the fuse following the instructions of ‘Mains Operating
Voltage’ section 4.1.