8
3
Installation
3.1
Supply Connections
Before applying power to the instrument, ensure that the voltage selector on the rear
panel is correctly set for the intended supply voltage.
If necessary, open the voltage selector panel using the slot provided, withdraw the
voltage selector and replace it in the correct orientation for the intended voltage. Check
that the correct fuses are fitted, then close the voltage selector panel.
Fuse ratings are:
100-120v1.6A Type T (Slow Blow)
200-240v0.8A Type T (Slow Blow)
3.2
Probe Connections
Probes are connected by means of 9-way D-sockets on the rear panel. Up to 3 of these
may be fitted, depending upon the instrument type. Their position corresponds logically
to the associated display on the front panel. Probes 1 and 2 may be used for either
Helium or Nitrogen. Probe 3 may only be used for Nitrogen. Pin outs used are the same
for either probe and no damage will be caused if the wrong type of probe is plugged in
by mistake.
Pin Connections are:
Pin
Name
Helium Probe
Nitrogen Probe
1
VHIGH
V (Top)
n/c
2
VLOW
V (Bottom)
n/c
3
(Unused)
4
FREQ IN
Link to 5
OUTPUT FREQ
5
FREQ OUT
Link to 4
n/c
6
I
HIGH
I (Top) n/c
7
I
LOW
I (Bottom)
0 V
8
+12 V
n/c
+12 V
9
CHASSIS GND
SCREEN
SCREEN
3.3
Compatibility with Earlier Probes
The design of the Helium Probe for the ILM family is unchanged from that for earlier
instruments, except for the type of connectors used. Old style probes may be used with
the new meter, provided a suitable interconnecting lead is used.
The design of the Nitrogen Probe, though based on the same principle, has changed in
detail. Old style probes are not compatible with ILM and should not be connected to it.
