32
10
Wiring Information
To measure the resistances of the heaters and sensors, the easiest way is to disconnect the
cables from the controller, and measure between the pins of the D-plugs.
The 15 way D-sockets on the controller labelled “Cryojet dewar leg” and “Shield unit” are
identical
. You can monitor voltage outputs to the coldhead while the jet is running by
disconnecting the shield unit from the controller (or
vice versa
), and connecting a
voltmeter across the pins of the socket you have disconnected.
10.1
Shield Unit
Component
Pins on 15
way D-
connector
Pins on round
connector fixed
to shield leg
Typical resistance
between pins,
(when
disconnected
from controller),
ohms
Typical output of
controller
measured using
the spare socket
“Cryojet dewar
leg”, when shield
leg is plugged in
Boiloff
heater
2 and 10
7 and 8
35 - 40
up to about 40
volts, depending
on flow
Heat
exchanger
heater
3 and 11
5 and 6
35 - 40
up to about 40 V,
fluctuating
Platinum
sensor
5 and 13
(or 5 and 14)
1 and 2
(or 1 and 4)
about 105 ohms
at room temp,
falling to 20
ohms at 70 K
pins 5 and 14:
100 mV at room
temperature
Leads for
platinum
sensor
13 and 14
2 and 4
about 1 ohm
