Teledyne LeCroy DXC100A - Manual (Page 12)

DXC100A Differential Probe Pair
10 922259-00 Rev A
b. Adjust R6 (-X10 DC) to bring the DA1855A output to center screen (0
volts) on the oscilloscope. This is a very critical adjustment, and it is
desirable to disconnect both probes from the source simultaneously (by
removing the BNC T) and observe that the trace stays within 0.25 div
(60,000:1 CMRR) between the two conditions.
4. +Input X100 DC Attenuation
a. Continuing from the previous step, set the probe to the 100X position.
b. Set the voltage source to 300 volts.
c. Press the VComp button. Measure DC source with DVM and note the
actual voltage (e.g. 302,617).
d. Set the Precision Voltage Generator to equal the noted voltage (see
footnote).
e. Set the oscilloscope to 10mV/div and 10μs/div.
f. Press the +Input DC button.
g. Press the X10 Gain button (to invoke AUTOBALANCE).
h. Adjust R23 (+X100 DC) to bring the DA1855A output to center screen (0
volts) on the oscilloscope. A 1 division error is equivalent to 100Mv out
of 300 V, or 0.03%, OR 330 ppm.
5. X100 DC CMRR
a. Continuing from the previous step, press the –Input DC button.
b. Set the oscilloscope to 2mV/div.
c. Press X10 Gain to invoke AUTOBALANCE.
d. Adjust R24 (-X100 DC) to bring the DA1855A output to center screen (0
volts) on the oscilloscope. This is a very critical adjustment, and it is
desirable to disconnect both probes from the source simultaneously and
observe that the trace stays within 0.5 div between the two conditions.
0.5 divisions is equivalent to a CMRR of 30,000:1 (300V/10mV).
e. Press the +Input Off button.
f. Press the –Input Off button.
g. Disconnect both probes and the DVM from the voltage source.