Cleaning
Periodically clean your meter’s case using a damp cloth.
DO NOT
use
abrasive, flammable liquids, cleaning solvents, or strong detergents as
they may damage the finish, impair safety, or affect the reliability of the
structural components.
Battery, Fuse and Test Load Replacement
Always use a fresh replacement battery of the specified size and type.
Immediately remove the old or weak battery from the meter and
dispose of it in accordance with your local disposal regulations. Batteries
can leak chemicals that corrode electronic circuits. If your meter is not
going to be used for a month or more, remove and store the battery in
a place that will not allow leakage to damage other materials. This
meter uses a single standard 9V battery (NEDA 1604, JIS006P, IEC 6F
22), a 1000V/440 mA IR 10 kA fast acting F fuse for mAµA current input,
and a 1000V/11A IR 10 Ka fast acting F fuse for A current input
WARNING!
Disconnect the test leads from the circuit under test and from the meter
prior to removing or installing batteries.
To install a new battery, follow these procedures:
1. Turn off the meter.
2. Remove the rubber boot from the meter, starting at the top.
3. Place meter face down on a clean cloth.
4. Remove the screws from the rear case. Two machined screws
fasten the bottom and two self-tapping screws fasten the top.
5. Separate the two halves to expose the battery.
6. Remove and discard the old battery. Always dispose of old batteries
promptly in a manner with local disposal regulations.
WARNING!
Under no circumstances should you expose batteries to extreme heat or
fire as they may expose and cause injury.
7. Place a fresh 9V battery in the battery clip.
8. Reassemble the meter.
Tro u b l e s h o o t i n g
If the meter fails to operate even with the battery or fuse replacements,
check twice according to operating procedures as described in this manual.
If the meter’s V/ input terminal was subjected to high voltage tra n s i e n t
( caused by lightning or switching surge to the system) by accident or
abnormal operating conditions, the series fusible resistors will be blown in
order to protect the user and the meter. Most measuring functions through
this terminal will then be open circuit.
In this case, the series fusible resistors and the spark gaps should be
replaced by qualified personnel. Refer to the
L IMITED WA RRA NTY &
L IMITATIONS OF L I A BIL ITY
section for obtaining warra n ty or
repairing serv i c e .
DM391/393-MAN
P. 6
Tips for Measuring Current
• When measuring a 3-phase system, special attention should be taken
to the phase to phase voltage which is significantly higher than the
phase to earth voltage. To avoid exceeding the voltage rating of the
protection fuse(s) accidentally, always consider the phase to phase
voltage as the working voltage for the protection fuse(s).
• When measuring current, the meter’s internal shunt resistors
develop a voltage across the meter’s terminals called “burden
voltage”. This voltage drop may affect precision circuit
or measurements.
Auto/Manual Range Operation
Press the “
RANGE
” push-button momentarily to select manual-ranging
in volts, ohms, and current measurement functions, and the meter will
remain in the range it was in, when the LCD annunciator “
AUTO
”
turns off.
Press the button momentarily again to step through the ranges.
Press and hold the “
RANGE
” push-button for 2 seconds to resume
auto-ranging.
Note:
M a n u a l - ra n ging feature is not available in Hz (Duty), CAP, TEMP,
and functions.
Auto Power-Off
The Auto-Power-Off feature automatically turns the meter off to extend
battery life after approximately 30 minutes of no activities. To turn on
the meter after Auto-Power-Off, turn the rotary switch from OFF to any
function (ON).
M a i n t e n a n c e
Periodic Service
WARNING!
Repair and service of this instrument is to be performed by qualified
personnel only. Improper repair or service could result in physical
degradation of the meter. This could alter the protection from
electrical shock and personal injury this meter provides to the
operator. Perform only those maintenance tasks that you are
qualified to do.
These guidelines will help you attain long and reliable service from
your meter:
• Calibrate your meter annually to ensure it meets original
performance specifications
• Keep your meter dry. If it gets wet, wipe dry immediately.
Liquids can degrade electronic circuits
• Whenever practical, keep the meter away from dust and
dirt that can cause premature wear
• Although your meter is built to withstand the rigors of daily
use, it can be damaged by severe impacts. Use reasonable
caution when using and storing the meter
