Service Note : Replacing AC High Voltage Divider Chain (30XX, 40XX, 90XX Calibrators)

Modified on Wed, 03 Mar 2021 at 08:31 AM

Note - This modification is only required for units that have older individual resistors that have failed due to component failure outside of Transmille's control.

Warning - This modification should be performed by skilled engineers only, and the unit WILL require FULL RE-CALIBRATION of the 200 and 1000V AC Ranges after completion.

This modification replaces R71, R72, R73, R74 and R75 on the mid board assembly of 30XX/40XX and 90XX Calibrators. These resistors are all nominally 210k and are replaced by a single 1M05 Resistor.

1. Locate the high voltage divider chain on the MID Assembly. This requires disassembly of the unit.

2. Prepare the CADDOCK part for installation. This requires the legs to be bent slightly to align with the holes in the board. Make sure that the LEG is bent and avoid placing undue stress on the body of the resistor.

3. Remove the existing Resistors (R71, R72, R73, R74 and R75) and install the CADDOC 1M05 part across R71 and R74, and then install a wire link across R75.

4. The modification is now complete.

The 200V and 1000V AC Ranges will require full re-calibration as this modification will affect both the gain and frequency response of the calibrator.

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