48
Maintenance
The Manufacturers or their agents overseas will provide a repair service for any unit developing a
fault. Where owners wish to undertake their own maintenance work, this should only be done by
skilled personnel in conjunction with the Service Guide, which may be obtained directly from the
Manufacturers or their agents overseas.
Cleaning
If the instrument requires cleaning use a cloth that is only lightly dampened with water or a mild
detergent.
WARNING! TO AVOID ELECTRIC SHOCK, OR DAMAGE TO THE INSTRUMENT, NEVER
ALLOW WATER TO GET INSIDE THE CASE.
TO AVOID DAMAGE TO THE CASE NEVER CLEAN WITH SOLVENTS.
Fuses
The only replaceable fuse in the instrument is an internal fuse on the power supply PCB, which is
intended to protect the unit from the accidental connection of 230V mains supply to a unit which
is configured for 115V operation. Before replacing this fuse, first disconnect the instrument from
all voltages, then remove the cover (6 screws) and ensure that the unit is configured correctly, as
described in the ‘Installation’ chapter of this manual. The correct replacement fuse is:
20x5mm 500mA time-lag (T) 250Vac rated HBC (ceramic tube) fuse.
The transformer primaries are protected by non-resetting thermal fuses inside the windings,
which can only be replaced by fitting new transformers. The secondary circuits are protected by
encapsulated fuses soldered to the PSU PCB. See the Service Guide for replacement details.
Calibration
To ensure that the accuracy of the instrument remains within specification the calibration must be
checked (and if necessary adjusted) annually. The procedure is detailed in the Service Guide,
which also lists the calibrated test equipment required.
Firmware Update
The firmware of the instrument can be updated through the USB port using a PC software utility
available from the manufacturer. This uses a HID (human interface device) USB class driver
which will already be installed on any PC with a USB port. Instructions for the update procedure
are provided with the PC utility and the firmware file.
Troubleshooting
If the instrument does not seem to be operating as expected, check the following before
suspecting a fault.
1. Check the position of the EXT – INT remote voltage sense switch on the rear panel.
2. Check that the voltage drop across the interconnecting cables between source and load is
not excessive, especially if remote sensing is being used. The actual voltage at the input
terminals of the load must meet the minimum operating voltage requirement for the current
level expected. Use a DVM to measure the actual voltage at the terminals.
3. If using a mode other than Constant Current (especially Constant Power or Voltage) consult
the ‘Application Notes’ chapter of this manual for guidance, especially concerning start-up
conditions and stability considerations.
4. If the Input trips as soon as it is enabled, this is often an indication of instability.
5. If the Dropout facility is not required, check that the Dropout Voltage is set to zero.
6. Enter the
Utilities
menu, perform
Restore Factory Defaults
and re-configure from scratch.
7. Read the whole of this manual carefully, as operation of the load, and its interactions with the
source, can be quite complex.
