Valleylab Force FX-8C - Check and Adjust the Current Sense Gain

Calibrating the Generator
5-30 Force FX-8C Service Manual
Step 5 – Check and Adjust the Current Sense Gain
Equipment required:
• Two short test cables (less than 61 cm [24 in.] long) with banana plugs
• Current transformer (such as the Pearson Model 411 or equivalent)
• True RMS voltmeter (such as the Fluke 8920 or equivalent)
• 10 ohm noninductive power resistor (such as the Dale NH-250)
• Bipolar footswitch and monopolar footswitch.
Verify that the Bipolar display shows calibration step number 5. The Cut
and Coag displays show the I (current) factor. If it is four or more digits,
the most significant digits appear in the Cut display.
Checking the Current Sense Gain for Bipolar Output
1. Connect the test equipment for bipolar output.
a. Connect the two test cables to the Bipolar Instrument receptacle.
b. Pass one test cable through the current transformer and connect the
current transformer to the voltmeter.
c. Connect the 10 ohm resistor across the output jacks at the end of
the test cables.
d. Connect the bipolar footswitch to the Bipolar Footswitch receptacle
on the rear panel.
Caution
To avoid inadvertent coupling and/or shunting of RF currents around the resistor
elements, keep the resistors at least 10.2 cm (4 in.) away from any metal surface
including tabletops and other resistors. This is especially true if several resistors
are connected in series or parallel to obtain a specified value. Do not allow the
resistor bodies to touch each other.
Notice
Do not activate the generator with any load resistor higher than 10 ohms while
calibrating the current sense gain. Otherwise, product damage will result.
Do not adjust the current sense gain while the generator is activated.