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In this case, an intermediate electrode extension is attached between the DPM and the reference
electrode to act as one of the data-probes and a second data-probe is fashioned using a regular
electrode extension and a reference electrode. The test lead supplied with the DPM kit is then used to
connect the DPM (via its banana jack input) to the second data-probe. The DPM will then read the
potential difference between the two locations on the ground to which the reference electrodes are in
contact.
Maintenance of the DPM
The battery should be replaced whenever the battery symbol shows in the display window. If the battery
symbol is suddenly displayed during a normal day of test activities, you may finish out the day of testing
before having to replace the battery. On the other hand, if the symbol is displayed the first time the meter is
used after a period of being idle, the battery should be replaced at once.
The meter should be kept reasonably clean by wiping with a cloth and then allowed to dry before placing
back in the carrying case.
The meter and the electrode assembly are reasonably watertight and will float if accidentally dropped into
water. However, the meter should be immediately removed from the water, wiped with a towel and allowed to
dry thoroughly before placing it back into the case. If the period of immersion is more than a few seconds, the
three 4-40 screws on the top of the meter body should be temporarily removed and any accumulated moisture
should be allowed to evaporate before placing the meter back in use.
It is a good idea to store the meter and electrode in the padded case when not in use.
Please consult
M. C. Miller’s instruction manual titled, “How to Prepare and Maintain Portable M. C. Miller Copper Sulfate
Reference Electrodes”, which is Manual # 270, for details on long- and short-term storage of reference
electrodes.
If the meter is accidentally dropped, it is a good idea to check it by connecting to a brand new “D” cell battery.
If meter reads between 1.5V and 1.6V, it probably did not become damaged. Digital meters usually read
correctly or not at all, unlike analog meters which can experience mechanical problems after being dropped.
Installing a New Battery
The current drain is quite small and only occurs when one or both of the range buttons are being
pressed. This means that you should anticipate a long battery life.
Almost any 9V battery can be used in your meter. The alkaline type, such as Energizer or Duracell type,
will last longer since their shelf life (up to 4 years) is longer than the cheaper, standard type carbon-zinc
battery.
Replacement Procedure
To gain access to the battery, slide off the orange plastic protective cover from the upper end of the
meter body. Then remove and save the three 4-40 screws from the meter bezel.
(Please note the
position of the meter relative to the position of the push button switch on the tube. Reinsert in the
same manner.)
Gently withdraw the meter assembly from its case until the battery is accessible.
