It should not be necessary for users to alter array voltages. However, the following description of the procedure is included for reference, and to describe some of the cosmetic features that indicate that adjustment is necessary.
Voltage adjustment is best done using the Idle Display and readout
method 3. Ensure that the array has stabilized at its operating
temperature of 32 K. All voltages are negative, but absolute values
are discussed here, i.e., increasing a voltage means make it a bigger
negative number. Look at something bright (the dome) with 0.5''
pixels and the 5 
grism slit so that the illuminated
pixel saturate. Look for a dark vertical stripe down the full length
of the array at the location of the slit. If this is seen, increase
V3 to remove it. Now look for a brightening at the left hand side of
the top array row in the Idle Display and a darkening of the middle of
the bottom array row. If this is seen, decrease V3. V3 must be made
small enough to remove the edge row effects, but large (i.e.,
negative) enough so as not to have vertical darkening around saturated
objects. Now reduce Vgg(on) until the vertical darkening reappears,
and increase it again so the vertical darkening has just disappeared.
The default array voltages are read from the file IR_CASPIR:ARRAY_PAR.DAT. This file must be edited if new array voltages are to be set on startup.