Adjust Low Frequency Cmrr (R7) - LeCroy AP034 Instruction Manual

C. Adjust Low Frequency CMRR (R7)
AP034-OM-E Rev D
7. Using a low capacitance screwdriver, adjust Fine DC
Balance (R304) until the ÷10 EFFECTIVE GAIN indicator
lights (Figure 11).
AP033 Logic Board
Figure 11. ÷11 Effective Gain Indicator
8. Disconnect the BNC cable from the short connector.
Remove the shorting plug from the logic board.
1. Leave the BNC cable connected to the probe end of the
ProBus extension cable. Connect a 50 Ÿ %1& 7KURXJK
Terminator on the other end of the BNC cable. Connect the
male end of the 50 Ÿ WHUPLQDWRU WR FKDQQHO  RQ WKH VFRSH
The scope end of the ProBus extension cable should
remain connected to channel 1 of the scope, although there
is no signal cable connected.
2. Connect a BNC cable from the output of the Function
Generator to the Channel 2 input of the oscilloscope.
3. Connect a second BNC cable from the Function Generator
SYNC OUT to the external trigger input of the oscilloscope.
4. Set the Function Generator waveform to Sine and the
frequency to 70 Hz.
ISSUED: January 2000
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Effective Gain Indicators
Adjustment too far
counter-clockwise
÷10 Indicator:
Adjustment correct
Adjustment too far
clockwise
²