Lake Shore 625, User Manual

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Lake Shore Model 625 Superconducting MPS User’s Manual
4-16 Operation
Use the
s
or
t
key to select the external current program mode, Internal, External, or Sum. Press Enter to accept the
new selection and return to the normal display. Press Escape to cancel the new selection and return to the normal
display.
To avoid discontinuities in the output current, the external current programming mode cannot be changed if the
programming voltage is not zero or the front panel current setting is not zero. If the external current program mode is
going to be kept from changing, an error box will pop up explaining why the new setting is going to be ignored. These
error boxes are shown below.
Change not allowed while
Programming voltage is not zero.
Change not allowed while
Current output setting is not zero.
4.19 LOCKING THE KEYPAD
The keypad lock feature prevents accidental changes to parameter values. When the keypad is locked, parameter values
may be viewed but cannot be changed from the front panel. The Model 625 has two keypad lock modes. The lock all
mode locks out changes to all parameters. The lock limits mode locks out changes to all of the parameters except Output
Setting, Ramp Rate, Voltage Limit, Zero Output, Stop Output, Pause Output, PSH On, and PSH Off. This allows the
power supply to be operated without allowing any changes to the power supply setup.
A 3-digit code must be used to lock and unlock the keypad. The factory default code is 123 and it can only be changed
using a computer interface. If the instrument parameters are set to default values, the code is reset to the factory default.
The instrument parameters cannot be reset to default values from the front panel when the keypad is locked.
The following message box appears on the display if the user attempts to change a parameter while the keypad is locked.
Change not allowed while
Keypad is locked.
NOTE: The computer interface has a remote operation mode that may be mistaken for a locked keypad. If the front
panel Remote LED is lit, press the Local key to change to local control of the instrument.
To lock or unlock the instrument keypad press and hold the Enter key for 5 seconds. The following setup screen appears
as a prompt for the keypad lock mode.
Keypad Lock
Select With °®
Keypad Lock: Unlock
Use the
s
or
t
key to select the keypad lock mode, Unlock, Lock All, or Lock Limits. Press Enter to choose the new
selection and continue to the keypad lock code verification. The change to the keypad lock mode is not made until the
correct keypad lock code has been entered. Press
Escape to cancel the new selection and return to the normal display.