Lakeshore Learning Materials 622 - Manual (Page 64)

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual
5-6 Error Messages & Troubleshooting
17. Send IZER to force output current to 0 amps. Verify a DVM reading of 0V ±0.01V. Allow MPS output to
settle for 2 minutes.
18. Convert DVM voltage reading to current. A reading of +0.000345V equals +0.345A. Send actual current
using CALZ+xxx.xxxx. If actual current is +0.345 amps, send CALZ+0.3450. The MPS determines the
zero current calibration constant.
19. Send ICAL50 to inform MPS of output current calibration and to force output current to +50 amps. Verify a
DVM reading of +0.05V ±10%. Allow MPS output to settle for 2 minutes.
20. Convert DVM voltage reading to current. A reading of +0.512345V equals +51.2345A. Send actual current
with CALPL+xxx.xxxx. If actual current is +51.2345A, send CALPL+51.2345. The MPS determines the
positive current calibration constant.
21. After the MPS determines the positive current calibration constant, it automatically sets output current to
the same value with the opposite sign. Verify that the DVM reads -0.05V ±10%. Allow MPS output to settle
for 2 minutes.
22. Convert voltage reading from DVM to current. A reading of -0.0487655V equals -48.7655A. Send actual
current with CALMN-xxx.xxxx. If actual current is 48.7655A, send CALMN-48.7655. The MPS
determines the negative current calibration constant.
23. The MPS stores the zero, positive, and negative current calibration constants then sets output current to
0. Verify a DVM reading of 0V ±0.00005V before continuing the calibration.
24. Use IMAX and STPS to restore IMAX and output current step to Step 7 values.
25. Turn off MPS and disconnect calibration loads.
26. Restore original Control Bus Serial Interface settings.
27. Disable MPS calibration. Turn OFF (down) CAL AND ID switch 8.
5.4 PERFORMANCE TEST
Performance tests verify proper MPS operation into a resistive load without testing all specified parameters.
The tests include no troubleshooting information, but can provide information that may localize faults. If any
tests fail, contact authorized service personnel.
WARNING: For service, return MPS to Lake Shore or a factory representative. Lake Shore Cryotronics,
Inc. cannot be held liable for injury or death of personnel attempting unauthorized MPS repairs.
Test Equipment Required
1. Current monitor shunt, 100 mV output, rated at 150 A . Manufacturers typically stock this shunt value. If a
different value is used, adjust readings given in the procedure.
2. Digital Volt Meter (DVM) capable of reading DC voltage from 100 mV with 0.1 mV accuracy to 35 V with
0.1 V resolution.
Performance Test Procedure
The test procedure includes both front panel and remote operation. Execute the performance tests in the
order given. Note any non-compliance.
Test Setup
1. Connect input power to the MPS as outlined in Sections 2.5 through 2.5.3 of this manual.
2. Disconnect any leads from MPS output terminals.
3. Set Programming Mode Switches on the MPS rear panel(s) to the INT (up) position. Set the CAL and ID
switch 7 OFF (down).
4. Turn ON MPS. Initially, the display clears and the alarm sounds for a short time. Within two seconds, the
Normal Display appears.