Monroe Electronics Charge Plate - Analyzer - model 268A - Manual (Page 9)

Section 4
MAINTENANCE
GENERAL:
Field maintenance of Model 268A should be limited to cleaning of the insulating
standoffs, cleaning of the case and occasional field-meter zero adjustment.
Further repairs and adjustment require special equipment and are beyond the
scope of this manual.
Factory service is advised.
CLEANING, INSULATORS:
The insulating standoffs (supporting the measuring plate) are specifically
designed to minimize the effects due to contamination of their outer surfaces.
Leakage paths created by the skin oils in fingerprints, tobacco smoke, dust, etc.
will eventually degrade their performance such that the self-decay rate of the
plate will exceed 10% over a five-minute period, indicating the need for cleaning.
IMPORTANT!
DO NOT USE SOAP, DETERGENT OR TAP WATER
TO CLEAN THESE INSULATORS
Clean the exposed surfaces of the insulators with mixture of 70% clean technical
grade isopropyl alcohol and 30% distilled water, using a soft toothbrush. The unit
should be inverted while doing this to minimize the amount of liquid entering the
case.
The insulators should then be allowed to air-dry.
CLEANING, CASE:
General cleaning of the case for aesthetic reasons is best done with a clean lint-
free cloth or wiping pad dampened in the alcohol/water solution noted above.
FIELDMETER ZERO:
Airborne contaminants entering the sensitive aperture of the fieldmeter probe
may cause a zero shift, which will affect the accuracy of measurement.
A multi-turn potentiometer is provided on the upper section of the instrument to
adjust fieldmeter zero. Adjust for an indication of zero volts on the 2000 volt
meter range with the ZERO button pressed in.