17 cannot use remote communications commands, Service – American Magnetics 03300PS-430-601 High Stability Integrated Power Supply System User Manual
Page 165
Rev. 5
147
Service
Troubleshooting Hints
proper current for the installed switch. Excessive currents cause
excessive boiloffs. The typical switch requires approximately 45 mA
to function correctly. Refer to the documentation provided with the
magnet for proper operating current. See Figure 3-13 on page 77.
2. Verify that the protective diodes on the magnet are not turning on.
Damaged diodes may short causing current to flow through them
whenever magnet current flows and cause excessive heating. This
can be identified by observing a change in the apparent field-to-
current ratio since some of the current is bypassing the coil. If the
boil off rate returns to normal with the magnet de-energized, this
may indicate a defective diode.
3. Ensure that there are no inadvertent thermal paths between the
cryogenic environment and the 300K environment. Ensure all
transfer lines are removed from the cryostat; check the position of
break-away vapor-cooled current leads.
4. Ensure the LHe level sensor is not continuously energized if
continuous level indication is not necessary.
5. Ensure the vacuum in vacuum-jacketed dewars is of sufficiently
low pressure.
5.2.16 Cannot display the magnetic field strength, only current
Enter a coil constant in accordance with section 3.10.2.2 on
Note
Setup menu limits are always required in terms of current.
5.2.17 Cannot use remote communications commands.
1. Verify your communications cable integrity and wiring. Refer to
Table A-8 on page 160 and Table A-9 on page 160 for wiring of
remote communications connectors.
2. Check to make sure you are sending the correct termination to the
Model 430 Programmer. If you are using RS-232, make sure the
baud rate, number of stop bits, and data bits/parity settings of the
host device are matched to those of the Model 430 Programmer (see
section 4.3). If you are using Ethernet communications, check all
Model 430 Programmer network settings (see sections 3.10.4 and