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Model 2657A-PM-200 Protection Module
PA-1055 Rev. A / February 2012
15
Verify diodes between LO / sense LO and chassis
A Keithley SourceMeter
instrument capable of sourcing 10 mA at 50 V is required for verification procedures C
and D.
A safety shield must be used whenever hazardous voltages (>30 V RMS, 42 V peak) will be
present in the test circuit. To prevent electrical shock that could cause injury or death, never
use a Keithley SourceMeter
®
instrument in a test circuit that may contain hazardous voltages
without a properly installed and configured safety shield. The following procedures show the
use of a metal safety shield. Connect the enclosure of the metal test fixture to protective earth
(safety ground).
If using a nonconductive test fixture, it must be rated to double the maximum capability of the
test equipment in the system and the two green-yellow ground cables for the Model 2657A-
PM-200 must be connected to protective earth (safety ground). Failure to attach the ground
wires to a known protective earth may result in electric shock.
Verification procedure C
Verify the operation of the diodes between Sense LO and the chassis of the Model 2657A-PM-200:
1. As shown in the connection drawing below, connect the source-measure unit (SMU) to the SL triaxial connector
of the protection module:
a. Connect the SMU force HI terminal to the center conductor of the SL OUT triaxial connector of the
Model 2657A-PM-200.
b. Connect the SMU force LO terminal to the outer shield (chassis) of the SL OUT triaxial connector of the
Model 2657A-PM-200. The chassis is available at the outer shield of any of the triaxial connectors on
the Model 2657A-PM-200.
Figure 11: Connections for verification procedure C