4-10
Model 2790 SourceMeter
®
Switch System User’s Manual
NOTE
For high ohms measurements (>1G
Ω
), it is recommended that the DUT be con-
nected between two different banks (for example, Bank 1 and Bank 3 as seen in
test connection figures) to reduce the possibility of measurement error caused by
leakage resistance.
Switching module installation
Module slot considerations
Only one Model 7753 module can be installed in a Model 2790, and it should be installed
in slot 1. A 7753 module can be used in slot 2, but measurement accuracy might be
adversely affected because cards are always calibrated in slot 1.
Power supply restrictions with the 7753 module
Under some conditions (low line, maximum current draw), two 7753 modules could draw
enough power to cause the Model 2790 to reset. To avoid this situation, installed modules
are checked at power-up. If a 7753 module is present, the other slot must be empty or pop-
ulated with a 7702 module.
If this condition is violated (a Model 7753 plus any other 775x module), the Model 2790
will lock up with the message “1 7753 ONLY” displayed, and all annunciators will turn
on. In this case, you must remove one module and cycle power to continue.
Installation procedure
A Keithley switching module simply slides into one of two slots in the rear panel of the
Model 2790:
1.
Turn off the Model 2790 and make sure there is no external power connected to it
or the module. External sources should never be used anywhere in the test system
to take advantage of the 2790 improvements that reduce the risk of airbag
detonation.
2.
If a slot cover is installed, remove it and retain for future use.
3.
With top cover side up, slide the connector end of the module into the mainframe.
Make sure the front edge of the card is in the track for the slot.
4.
Push the module all the way in until it mates with the backplane connector of the
mainframe.
5.
Hand-tighten the two screws that secure the module in the mainframe. Tightening
these screws connects the module to chassis ground.