ACL MODEL #400
CALIBRATION INSTRUCTIONS

CALIBRATION

The ACL 400 has only three adjustments:

**Mechanical ZERO for the meter movement

**ZERO - an internal control accessible through the battery case by removing the case by removing the case cover and pulling out to the full length of its cable.

**CAL - similarly accessible.

It is recommended that adjustments are made and accuracy is checked only at the one-inch spacing specified, as at greater spacing the test voltage and dimensions of the calibration target become unwieldy.

A. EQUIPMENT REQUIRED:

1) Monroe Electronics, Inc. Model #251 x 10kv High Voltage Supply or equivalent capable of 1000 and 10,000 volt output to better than 1% accuracy.

2) Digital Multimeter - 3% digit - Data Precision Model DP-1450 or equivalent.

3) Subminiature phone plug with leads (for output jack) - Switchcraft part #850 or equivalent.

4) A test fixture consisting of a one-foot square metal plate supported vertically and isolated from ground by insulation capable of withstanding at least 10kv and means of positioning and supporting the metallic face of the electrode of the unit under test one inch away from and in the same plane as the approximate center of this plate.

B. TEST METHOD:

1) Place the unit under test in the face of the electrode is one inch away from the test surface.

2) Connect a clip lead between the receiver tray and the test surface.

3) With the function switch OFF, set the mechanical ZERO of the unit under test so that the needle points to center scale.

4) Install a known good battery.

5) Connect Digital Multimeter (DMM, Item A-2) to the OUTPUT jack using phone plug (Item A-3). Set the range on Model 400 to its X! position.

6) Switch the range on model 400 to its x1 position.

7) Zero the instrument using the DMM as indicator. The instrument will have to be lifted for each attempt. The ZERO control (R-12) is located through the battery case on the right-hand side as viewed from the normal operating position.

8) Switch the range switch to its x 1 position.

9) Remove the clip lead installed in step 2 above.

10) Connect the High Voltage Supply so that its output is connected to the target and the receiver tray is connected to the grounded return side of the supply.

WARNING!! The instrument will again have to be lifted to make the following adjustment. Beware of HIGH VOLTAGE !!!

11) Apply + 1000 volts to the target and adjust the CAL potentiometer (R-8) for an Indication of +1.000 on the DMM. The meter on ACL 400 should indicate full scale deflection (to the right), ± 10%. R-8 is located through the battery case on the left as the instrument is viewed in its normal operating position.

12) Apply - 1000 volts to the target. The DMM should indicate -1.000 VDC. R-8 may be readjusted for best compromise between this and the positive response. ZERO (R-12) should be rechecked for possible interaction. The meter should indicate full scale to the left within 10%.

13) Switch to the "X10" range.

14) Apply + 10,000 volts to the target and check output voltage. It should be +1.000 VDC, ±10%.Check for full-scale deflection of the meter (±10%).