UEi Test Instruments M75A - Manual (Page 2)

Introduction
The M75A has the features you need for testing electrical and HVAC/R
systems. Its voltage ranges are scaled to keep typical readings in the
middle of the scale for increased accuracy and resolution. It also
includes a low ohm scale to test critical connections as well as
microamps and millivolts functions to verify heat anticipator and flame
safeguard circuits.
Features include
• 17 ranges
• 1000 Volts AC and DC
• Resistance 50 kilohm
• DC micro/milli amps
• DC millivolt scale allows use of adapters
• Color-coded and mirrored scale plate
Safety Notes
Before using this meter, read all safety information carefully. In
this manual the word "WARNING" is used to indicate conditions
or actions that may pose physical hazards to the user. The word
"CAUTION" is used to indicate conditions or actions that may
damage this instrument.
C o n t rols and Indicators
1. Selector Switch: Is used to select the circuit function and range.
it is good practice to start with the highest range setting of the
selector switch for a particular function if the magnitude of the
function is unknown.
2. ΩADJ: Is used only on the OHMS function. The purpose of this
control is to calibrate the M75A on the particular range selected
(Rx1, Rx10, etc.)
3. Mechanical Zero Adjust: Is a plastic screw located on the
meter face just beneath the green “FUSE PROTECTED OHM
CIRCUIT” label. This adjustment is used to set the pointer to the
zero index mark at the left side of the scale plate.
4. Input Jacks:
COM (-): The black test lead is used to connect this jack to the
negative, or common, side of the circuit under test.
VΩM (+): This adjustment is used to set the pointer to the zero
index mark at the left side of the scale plate.
Operating Instructions
WARNING!
Observe all safety precautions when measuring higher voltages.
Turn off power to the circuit under test. Set the M75A controls,
connect the test leads to the meter and then to the circuit under
test. Reapply power. If the pointer does not move, make sure that
the protective fuse is not open.
Color Coding
The meter scale plate and front panel are color coded. The DC Voltages
and DC Current meter scale and “SELECTOR” switch positions are in
black. The OHMS meter scale and “SELECTOR” switch positions are in
green. The AC Voltage meter scales and “SELECTOR” switch positions
are in red.
To provide an uncrowded easy-to-read meter scale plate a single meter
scale may be used for more than one position of the “SELECTOR”
switch. For example, the meter scale numerals 0 - 50 are used for the
following positions of the “SELECTOR” switch: 50V DC, 50µA DC, 50V
AC and 500V AC. To take a reading at any of the above “SELECTOR”
switch positions the 0 - 50 scale numerals are either read directly or
divided by 10. Example: (1) If the “SELECTOR” switch is set on 50V DC
then read the numerals directly. (2) If the “SELECTOR” switch is set on
500V AC then multiply the 0 - 50 numerals by 10 (this will give a scale
of 0 - 500).
Measuring DC Voltage
Set the “SELECTOR” switch to the appropriate range. Always start with
the 1000V DC position if unsure of the magnitude of voltage present.
Connect the black test lead to the “COM” jack and to the negative side
of the circuit under test. Connect the red test lead to the “+VΩM” jack
and to the positive side of the circuit under test. Read the voltage on the
black meter scale corresponding to the “SELECTOR” switch setting.
Note: the 250mV DC and the 50µA DC readings are taken at the same
position of the “SELECTOR” switch.
M75A-MAN P. 1
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