RIDGID micro DM-100 User manual

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EN
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RIDGE TOOL COMPANY
micro
DM-100

micro DM-100 Digital Multimeter
Record Serial Number below and retain product serial number which is located on nameplate.
Serial
No.
micro DM-100
Digital Multimeter
WARNING!
ReadthisOperator’sManual
carefully before using this
tool. Failure to understand
and follow the contents of
this manual may result in
electrical shock, re and/or
serious personal injury.
micro DM-100

micro DM-100 Digital Multimeter
2
Lifetime Warranty...................................................................................................... Back Cover
*Original instructions
Table of Contents
Table of Contents........................................................................................................................... 2
Safety Symbols................................................................................................................................ 3
General Safety Rules.................................................................................................................... 3
Work Area Safety.......................................................................................................................... 3
Electrical Safety............................................................................................................................. 3
Personal Safety.............................................................................................................................. 3
Equipment Use and Care.......................................................................................................... 4
Service.............................................................................................................................................. 4
Specic Safety Information...................................................................................................... 4
Multimeter Safety ........................................................................................................................ 4
Description, Specications And Standard Equipment.............................................. 5
Description ..................................................................................................................................... 5
Specications................................................................................................................................. 5
Standard Equipment .................................................................................................................. 8
Controls............................................................................................................................................ 8
Icons .................................................................................................................................................. 9
FCC Statement...............................................................................................................................10
Electromagnetic Compatibility (EMC)..............................................................................10
Changing/Installing Batteries...............................................................................................10
Pre-Operation Inspection .......................................................................................................11
Set-Up and Operation ...............................................................................................................12
Rotary Function Switch................................................................................................................13
Input Terminals ...........................................................................................................................13
Pushbuttons.................................................................................................................................14
DC/AC Voltage Measurement...............................................................................................14
DC/AC Current Measurement...............................................................................................15
Resistance Measurement........................................................................................................15
Diode Test......................................................................................................................................16
Continuity Check........................................................................................................................16
Capacitance Measurement....................................................................................................16
Frequency Measurement........................................................................................................17
Temperature Measurement...................................................................................................17
Maintenance Instructions .......................................................................................................18
Cleaning.........................................................................................................................................18
Calibration.....................................................................................................................................18
Fuse Replacement .....................................................................................................................18
Accessories......................................................................................................................................18
Storage ..............................................................................................................................................19
Service and Repair.......................................................................................................................19
Disposal.............................................................................................................................................19
Battery Disposal...........................................................................................................................19
Troubleshooting...........................................................................................................................20

micro DM-100 Digital Multimeter
3
Safety Symbols
In this operator’s manual and on the product, safety symbols and signal words are used
to communicate important safety information. This section is provided to improve under-
standing of these signal words and symbols.
This is the safety alert symbol. It is used to alert you to potential personal injury
hazards. Obey all safety messages that follow this symbol to avoid possible injury
or death.
DANGER
WARNING
CAUTION
NOTICE
DANGER indicates a hazardous situation which, if not avoided, will result
in death or serious injury.
WARNING indicates a hazardous situation which, if not avoided, could re-
sult in death or serious injury.
CAUTION indicates a hazardous situation which, if not avoided, could result
in minor or moderate injury.
NOTICE indicates information that relates to the protection of property.
This symbol means read the operator’s manual carefully before using the equip-
ment. The operator’s manual contains important information on the safe and prop-
er operation of the equipment.
This symbol indicates the presence of a high voltage hazard.
This symbol indicates the risk of electrical shock.
General Safety Rules
WARNING
Read all safety warnings and instructions. Failure to follow the warnings and in-
structions may result in electric shock, re and/or serious injury.
SAVE THESE INSTRUCTIONS!
Work Area Safety
• Keep your work area clean and well lit. Cluttered or dark areas invite accidents.
• Do not operate equipment in explosive atmospheres, such as in the presence of
ammable liquids, gases or dust. Equipment can create sparks which may ignite the dust
or fumes.
• Keep children and by-standers away while operating equipment. Distractions can
cause you to lose control.
Electrical Safety
• Avoid body contact with earthed or grounded surfaces such as pipes, radiators, ranges
and refrigerators. There is an increased risk of electrical shock if your body is earthed or
grounded.
• Do not expose equipment to rain or wet conditions. Water entering equipment will
increase the risk of electrical shock.
Personal Safety
• Stay alert, watch what you are doing and use common sense when operating
equipment. Do not use equipment while you are tired or under the inuence of
drugs, alcohol or medication. A moment of inattention while operating equipment
may result in serious personal injury.

micro DM-100 Digital Multimeter
4
• Use personal protective equipment. Always wear eye protection. Protective equip-
ment such as as protective gloves and clothing, dust mask, non-skid safety shoes, hard
hat, or hearing protection used for appropriate conditions will reduce personal injuries.
• Do not overreach. Keep proper footing and balance at all times. This enables better
control of the equipment in unexpected situations.
Equipment Use and Care
• Do not force equipment. Use the correct equipment for your application. The cor-
rect equipment will do the job better and safer at the rate for which it is designed.
• Do not use equipment if the switch does not turn it ON and OFF. Any tool that can-
not be controlled with the switch is dangerous and must be repaired.
• Store idle equipment out of the reach of children and do not allow persons unfa-
miliar with the equipment or these instructions to operate the equipment. Equip-
ment can be dangerous in the hands of untrained users.
• Maintain equipment. Check for missing parts, breakage of parts and any other condi-
tion that may aect the equipment’s operation. If damaged, have the equipment re-
paired before use. Many accidents are caused by poorly maintained equipment.
• Use the equipment and accessories in accordance with these instructions, tak-
ing into account the working conditions and the work to be performed. Use of the
equipment for operations dierent from those intended could result in a hazardous situ-
ation.
• Use only accessories that are recommended by the manufacturer for your equip-
ment. Accessories that may be suitable for one piece of equipment may become haz-
ardous when used with other equipment.
• Keep handles dry and clean; free from oil and grease. Allows for better control of the
equipment.
Service
• Have your equipment serviced by a qualied repair person using only identical
replacement parts. This will ensure that the safety of the tool is maintained.
Specific Safety Information
WARNING
This section contains important safety information that is specic to this tool.
Read these precautions carefully before using the RIDGID® micro DM-100 Digital
Multimeter to reduce the risk of electrical shock or other serious injury.
SAVE THESE INSTRUCTIONS!
Keep this manual with the tool for use by the operator.
Multimeter Safety
• Use caution when working with voltages above 30 V AC RMS, 42 V AC peak or 60
V DC. These voltages pose serious shock hazard. High-voltage circuits, both DC and AC,
are very dangerous and should be measured with great care. Avoid working alone.
• Do not connect to voltages that exceed 600 VAC or VDC relative to earth ground.
This may damage the meter and expose the operator to a shock hazard.
• When using the probes, keep your ngers behind the nger guards on the probes.
This reduces the risk of electric shock.
• Never ground yourself when taking electrical measurements. Do not touch exposed
metal pipes, outlets, xtures, etc., which might be at ground potential. Keep your body
isolated from ground using appropriate methods.

micro DM-100 Digital Multimeter
5
• When measuring current, turn o the circuit power before connecting the meter in
series with the circuit. Improper set up could result in electrical shock.
• When measuring resistance, disconnect all power (remove batteries, unplug cord,
discharge all capacitors, etc.) to the circuit being measured. This reduces the risk of
electric shock.
• After resistance test, the capacitive circuits must be discharged. This will help pro-
tect against electric shock.
• Use extreme caution when working near bare conductors and bus bars. Accidental
contact with conductors could result in electrical shock.
• Turn o power to the circuit under test before cutting, unsoldering, or breaking the
circuit. Small amount of current can expose the operator to a shock hazard.
The EC Declaration of Conformity (890-011-320.10) will accompany this manual as a sepa-
rate booklet when required.
If you have any question concerning this RIDGID® product:
• Contact your local RIDGID distributor.
• Visit www.RIDGID.com or www.RIDGID.eu to nd your local RIDGID contact point.
• Contact RIDGID Technical Services Department at rtc[email protected], or in
the U.S. and Canada call [phone].
Description, Specifications And Standard Equipment
Description
The RIDGID® DM-100 Digital Multimeter is a handheld instrument. The unit can measure DC
and AC Voltage and Current, Resistance, Capacitance, Frequency, Temperature, Continuity
(audible signal) and Test Diodes. The multimeter can automatically select the best range
for measurement.
The unit has data hold and relative measurement functions. Overload protection and low
battery indication are provided. The unit has a 4000-count backlight LCD.
The multimeter is powered by a 9V battery and has auto power-o function after 15 min-
utes of inactivity.
Specifications
Display ................................................................4000 Count backlight LCD
Overvoltage Category..................................CAT III 1000V, CAT IV 600V
Fuse Rating........................................................0.5A/1000V Fast Blow for the 400mA Range,
10A/1000V Fast Blow for the 10A Range
Insulation...........................................................Class 2, Double Insulation
Protection Rating............................................IP 67
Polarity................................................................Auto Polarity Indication
Operating Temperature...............................0°C to 50°C (32°F to 122°F)
Power Supply ...................................................9V Battery, NEDA 1604, IEC 6F22 or 6LR61
Weight.................................................................0.82 lbs (375 g)
Dimension.........................................................7.2" x 3.2" x 2.2" (182 x 82 x 55 mm)

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Input Limits
Function Maximum Input
Voltage V DC/AC 1000 V DC/AC
Current mA DC/AC 400 mA DC/AC
Current A DC/AC 10 A DC/AC
Frequency, Duty Cycle 600 V DC/AC
Accuracy is given at 18°C to 28°C (65°F to 83°F), less than 70% RH
DC Voltage (Autoranging)
Range Resolution Accuracy
400.0 mV 0.1 mV ±0.5% of Reading ± 2 Digits
4.000 V 1 mV
±1.2% of Reading ± 2 Digits40.00 V 10 mV
400.0 V 100 mV
1000 V 1 V ±1.5% of Reading ± 2 Digits
Input Impedance............................................7.8 MΩ
Maximum Input ..............................................1000V DC or 1000V AC RMS
AC Voltage (Autoranging)
Range Resolution Accuracy
400.0 mV 0.1 mV ±1.5% of Reading ± 70 Digits
4.000 V 1 mV ±1.2% of Reading ± 3 Digits
40.00 V 10 mV ±1.5% of Reading ± 3 Digits
400.0 V 100 mV
1000 V 1 V ±2.0% of Reading ± 4 Digits
Input Impedance............................................7.8 MΩ
AC Response.....................................................True RMS 50 Hz to 400 Hz
Maximum Input ..............................................1000V DC or 1000V AC RMS
DC Current (Autoranging for µA and mA)
Range Resolution Accuracy
400.0 µA 0.1 µA ±1.0% of Reading ± 3 Digits
4000 µA 1 µA
±1.5% of Reading ± 3 Digits40.00 mA 10 µA
400.0 mA 100 µA
10 A 10 mA ±2.5% of Reading ± 5 Digits
Overload protection......................................0.5A/1000V and 10A/1000V Fuse
Maximum Input ..............................................400 mA DC or 400mA AC RMS on µA/mA Ranges,
10A DC or AC RMS on 10A Range
AC Current (Autoranging for µA and mA)
Range Resolution Accuracy
400.0 µA 0.1 µA ±1.5% of Reading ± 5 Digits
4000 µA 1 µA
±1.8% of Reading ± 5 Digits40.00 mA 10 µA
400.0 mA 100 µA
10 A 10 mA ±3.0% of Reading ± 7 Digits
Overload protection......................................0.5A/1000V and 10A/1000V Fuse
AC Response.....................................................True RMS 50 Hz to 400 Hz
Maximum Input ..............................................400 mA DC or 400mA AC RMS on µA/mA Ranges,
10A DC or AC RMS on 10A Range

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Resistance (Autoranging)
Range Resolution Accuracy
400.0 Ω 0.1 Ω ±1.2% of Reading ± 4 Digits
4.000 kΩ 1 Ω ±1.0% of Reading ± 2 Digits
40.00 kΩ 10 Ω
±1.2% of Reading ± 2 Digits400.0 kΩ 100 Ω
4.000 MΩ 1 kΩ
40.00 MΩ 10 kΩ ±2.0% of Reading ± 3 Digits
Input Protection..............................................600V DC or 600V AC RMS
Capacitance (Autoranging)
Range Resolution Accuracy
4.000 nF 1 pF ±5.0% of Reading ± 0.5 nF
40.00 nF 10 pF ±5.0% of Reading ± 7 Digits
400.0 nF 0.1 nF
±3.0% of Reading ± 5 Digits4.000 uF 1 nF
40.00 uF 10 nF
200.0 uF 0.1 uF ±5.0% of Reading ± 5 Digits
Input Protection..............................................600V DC or 600V AC RMS
Frequency (Autoranging)
Range Resolution Accuracy
9.999 Hz 0.001 Hz ±1.5% of Reading ± 5 Digits
99.99 Hz 0.01 Hz
999.9 Hz 0.1 Hz
±1.2% of Reading ± 3 Digits
9.999 kHz 1 Hz
99.99 kHz 10 Hz
999.9 kHz 100 Hz
9.999 MHz 1 kHz ±1.5% of Reading ± 4 Digits
Sensitivity ..........................................................> 0.5 V RMS while ≤ 100kHz
Sensitivity ..........................................................> 8 V RMS while > 100kHz
Overload protection......................................600V DC or AC RMS
Duty Cycle
Range Resolution Accuracy
0.1% to 99.9% 0.1% ±1.2% of Reading ± 2 Digits
Pulse Width .......................................................> 100 µs, < 100 MS
Frequency Width ............................................5 Hz to 150 kHz
Sensitivity ..........................................................>0.5 V RMS
Overload protection......................................600V DC or AC RMS
Temperature
Range Resolution Accuracy
-20°C to +760°C 1°C ±3% of Reading ± 5°C / 9°F
-4 °F to +1400 °F 1°F
Sensor..................................................................Type K Thermocouple
Overload protection......................................600V DC or AC RMS
Diode Test
Range Resolution Accuracy
0.3 mA Typical 1 mV ±10% of Reading ± 5 Digits
Open Circuit Voltage.....................................1.5 V DC Typical
Overload protection......................................600V DC or AC RMS

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Audible Continuity
Audible Threshold..........................................< 150 Ω
Test Current.......................................................< 0.3 mA
Overload protection......................................600V DC or AC RMS
Standard Equipment
The RIDGID® micro DM-100 Digital Multimeter comes with the following items:
• micro DM-100 Digital Multimeter • Terminal Plugs
• Test Leads with Covers, Black and Red • User Manual and Instruction CD
• K Type Adapter and Temperature Probe • Carrying Case
Figure 1 – micro DM-100 Digital Multimeter
Test Leads
Temperature Probe
and Adapter
Terminal Plugs
Stand
Figure 2 – Back of micro DM-100 Digital Multimeter
Test Lead Holders
Warning Label
Controls
6
7
8
9
10
11
12
5
4
3
2
1
Figure 3 – DM-100 Digital Multimeter Controls
1. Large 4000 Count Liquid Crystal Display
2. Range Pushbutton (RANGE)
3. Frequency/%Duty Pushbutton (Hz%)
4. Mode Pushbutton (MODE)
5. Data Hold Pushbutton (HOLD)
6. Relative Pushbutton (REL)
7. Backlight pushbutton ( )
8. Rotary Function Switch
9. Positive Input Terminal for 0 to 10 A ( )
10. Positive Input Terminal for 0 to 400 mA ( )
11. Positive Input Terminal for DC/AC Voltage Measurement,
Resistance Measurement, Continuity Check, Diode Test,
Frequency Measurement, Capacitance Measurement
and Temperature Measurement ( )
12. COM (Negative) Terminal for all measurements ( )
(Not Shown – Backside of unit) Battery Door, Fuse Compart-
ment, fold out stand, Probe holder

micro DM-100 Digital Multimeter
9
Icons
Screen Icons 6 7 8 9 10
11
5
4
3
2
1
Icon Number Icons on Screen Description
1Low Battery.
2 — Polarity Indicator. Negative readings, In relative
mode, this sign indicates that the present input is
less than the stored reference value.
3 AC Alternating Current or Voltage.
4 DC Direct Current or Voltage.
5 AUTO Autoranging Mode is Active. Automatically selects
the best range for measurements.
6HOLD Data Hold is Active.
7 REL Relative Mode is Active.
8Diode Test Mode.
9Continuity Check Mode.
10 °C and °F Temperature Mode (Degree Celsius, Degree
Fahrenheit).
11 Ω, kΩ , M ohm, kilohm, Megohm
Hz, kHz hertz, kilohertz
% Percent. Used for Duty Cycle Measurements.
V, mV volts, millivolts
A, μA, mA amperes (amps), microamp, milliamp
μμF, nF microfarad, nanofarad
— OL Overload Condition.
Figure 4 – Screen Icons

micro DM-100 Digital Multimeter
10
On Product Icons
Double Insulation Symbol Fuse Symbol
Earth Ground Symbol 9V Battery Symbol
CAT III IEC Overvoltage Category III
CAT III equipment is designed
to protect against transients in
equipment in xed equipment
installations, such as distribution
panels, feeders and short branch
circuits, and lighting systems in
large buildings.
CAT IV IEC Overvoltage Category IV
CAT IV equipment is designed
to protect against transients
from the primary supply level,
such as an electricity meter or an
overhead or underground utility
service.
Conforms to European Union
directives
Do not dispose of electrical
equipment with household
waste!
NOTICE This equipment is used to make electrical measurements. Incorrect use or im-
proper application may result in incorrect or inaccurate measurements. Selection of appro-
priate measurement methods for the conditions is the responsibility of the user.
FCC Statement
This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reason-
able protection against harmful interference in a residential installation.
This equipment generates, uses, and can radiate radio frequency energy and, if not in-
stalled and used in accordance with the instructions, may cause harmful interference to
radio communications.
However, there is no guarantee that interference will not occur in a particular installation.
If this equipment does cause harmful interference to radio or television reception, which
can be determined by turning the equipment o and on, the user is encouraged to try to
correct the interference by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Consult the dealer or an experienced radio/TV technician for help.
Electromagnetic Compatibility (EMC)
The term electromagnetic compatibility is taken to mean the capability of the product to
function smoothly in an environment where electromagnetic radiation and electrostatic
discharges are present and without causing electromagnetic interference to other equip-
ment.
NOTICE The RIDGID micro DM-100 conforms to all applicable EMC standards. However,
the possibility of it causing interference in other devices cannot be precluded.
Changing/Installing Batteries
The RIDGID DM-100 Digital Multimeter is supplied without the battery installed. When the
low battery [ ] icon appears on the display screen, replace the battery. Operating
the multimeter with a low battery can cause incorrect readings. Remove the battery prior
to long-term storage to avoid battery leakage.

micro DM-100 Digital Multimeter
11
1. Switch OFF the device and disconnect
test leads.
2. Use a Phillips head screwdriver to
loosen the battery compartment cover
screws and remove the cover. Remove
existing battery.
3. Install 9V alkaline battery (NEDA 1604,
IEC 6F22 or 6LR61), observing the cor-
rect polarity as indicated on the bat-
tery compartment.
4. Securely install the battery compart-
ment cover. Do not operate without
the battery cover secured.
Pre-Operation Inspection
WARNING
Before each use, inspect your tool and correct any problems to reduce the
risk of serious injury from electric shock and other causes and prevent
tool damage.
1. Make sure the unit is OFF and the leads are not connected.
2. Clean any oil, grease or dirt from the equipment. This aids inspection and helps pre-
vent the tool from slipping from your grip.
3. Inspect the tool.
• For any broken, worn, missing or binding parts or any condition which may prevent
safe and normal operation.
• Conrm that battery compartment cover and back cover (fuse cover) are properly
secured.
• Inspect the test leads for damaged insulation or exposed wire. Check the test leads
for continuity.
• Check that the markings and warning label are present, rmly attached and read-
able.
If any issues are found during the inspection, do not use the tool until it has been properly
serviced.
4. Verify the meter operation (following the Set-Up and Operation Instructions).
• Turn the unit ON and conrm that the Low Battery icon is not ON.
• Perform a continuity test.
5. Do not use the meter if it operates abnormally. When in doubt, have the meter ser-
viced.
Battery
Compartment
Cover
Battery
Figure 5 – Changing Battery

micro DM-100 Digital Multimeter
12
Set-Up and Operation
WARNING
Set up and operate the Multimeter according to these proce-
dures to reduce the risk of injury from electric shock and other
causes, and prevent tool damage.
Use caution when working with voltages above 30 V AC RMS,
42 V AC peak or 60 V DC. These voltages pose serious shock hazard. High-voltage circuits,
both DC and AC, are very dangerous and should be measured with great care. Avoid work-
ing alone.
Do not connect to voltages that exceed 1000 VAC or VDC relative to earth ground.This
may damage the meter and expose the operator to a shock hazard.
When using the probes, keep your ngers behind the nger guards on the probes.
This reduces the risk of electric shock.
Never ground yourself when taking electrical measurements. Do not touch exposed
metal pipes, outlets, xtures, etc., which might be at ground potential. Keep your body
isolated from ground using appropriate methods.
Use extreme caution when working near bare conductors and bus bars. Accidental
contact with conductors could result in electrical shock.
1. Check for an appropriate work area as indicated in the General Safety section.
2. Inspect the work to be done and conrm that you have correct equipment for the ap-
plication. See the Specications section for range, accuracy and other information.
• To select a function, turn the rotary function switch to the appropriate position.
• Select the proper function and range for your measurement.
• Determine the voltage to be measured. Do not apply more than the rated voltage,
as marked on the meter, between terminals or between any terminal and earth
ground.
• When measuring current, turn o circuit power before connecting the meter in the
circuit. Remember to place the meter in series with the circuit.
• Turn the function switch to the OFF position after inspection.
3. Make sure all equipment being used has been properly inspected.
4. Use correct accessories for the application. Select the proper terminals, function, and
range for all measurements.
5. When making electrical connections, connect the common test lead (black) before
connecting the live test lead (red); when disconnecting, disconnect the live test lead
(red) before disconnecting the common test lead (black). Cover unused input termi-
nals with terminal plugs.
6. If “OL” appears in the display during a measurement, the value exceeds the range you

micro DM-100 Digital Multimeter
13
have selected, change to a higher range. On some low DC and AC voltage ranges, with
the test leads not connected to a device, the display may show a random, changing
reading. This is normal and is caused by the high-input sensitivity. The reading will
stabilize and give a proper measurement when connected to the circuit.
7. Always turn the function switch to the OFF position when the meter is not in use. The
meter will automatically shut OFF if not used for 15 minutes.
Rotary Function Switch
The Rotary Function switch permits the user to select a measurement function by position-
ing the rotary switch to one of the icons around its perimeter.
Figure 6 – Rotary Function Switch
Switch Position Function
OFF Switch O the Multimeter
DC/AC Voltage Measurement
Capacitance Measurement
Continuity Check and Diode Test
Resistance Measurement
Frequency Measurement
Temperature Measurement in °C
Temperature Measurement in °F
DC/AC Current Measurement up to
10 A
DC/AC Current Measurement up to
400 mA
DC/AC Current Measurement up to
4000 µA
Input Terminals
The black test lead plugs into the negative (COM) terminal and the red test lead plugs into
any of the three the positive input terminals according to the measurement to be made.
Use the provided terminal plugs in idle terminals during operation.
Figure 7 – Input Terminals
Terminals Description
10 A Input Terminal for 0 to 10 A
µA / mA Input Terminal for 0 to 400 mA
V / Hz% /
Ω / CAP /
TEMP
Input Terminal for DC/AC Voltage
Measurement, Resistance
Measurement, Continuity
Check, Diode Test, Frequency
Measurement, Capacitance
Measurement and Temperature
Measurement
COM Negative Terminal for all
measurements

micro DM-100 Digital Multimeter
14
Pushbuttons
Mode Button (MODE)
The Mode Button is used to select Ohms/Diode/Continuity or DC/AC current in the appro-
priate rotary switch settings.
Range Button (RANGE)
When the meter is turned on, it automatically goes into Autoranging. This automatically
selects the best range for the measurement being made and is generally the best mode for
most measurements. For selecting the range manually, perform the following:
1. Press the Range button. The“AUTO” display indicator will turn o.
2. Press the Range button to step through the available ranges until you select the range
you want.
3. Press and hold the Range button for 2 seconds to exit the Manual Ranging mode and
return to Autoranging.
Data Hold Button (HOLD)
The Data Hold function allows the meter to freeze a measurement for later reference.
1. Press the Data Hold button to freeze the reading on the display. The indicator “HOLD”
will appear in the display.
2. Press the Data Hold button to return to normal operation.
Relative Button (REL)
The relative measurement feature allows you to make measurement relative to a stored
reference value. A reference voltage, current or other value can be stored and measurement
can be made in comparison to that value.
1. Perform any measurement as described in the operating instructions.
2. Press the Relative button to store the reading in the display and the "REL" indicator will
appear on the display.
3. The display will now indicate the dierence between the stored value and the mea-
sured value.
4. Press the Relative button to return to normal operation
Backlight Button ( )
1. Press the Backlight button for 2 seconds to turn the display light on.
2. Press Backlight button again to exit the backlight mode.
Hz% Button (Hz%)
1. Press Hz% Button to measure Frequency or Duty Cycle while measuring voltage or
Current.
2. In Frequency mode, the frequency is measured in Hz units and in % mode the readings
from 0.1 through 99.9 are displayed.
3. Press Hz% Button to return to measurement of Voltage or Current.
DC/ACVoltage Measurement
NOTICE Do not measure DC/AC voltage if a motor (or other high current equipment) on
the circuit is being switched ON and OFF. Large voltage surges may occur that can damage
the meter.
Do not measure DC/AC voltage if a motor (or other high current equipment) on the circuit is
being switched ON and OFF. Large voltage surges may occur that can damage the meter.

micro DM-100 Digital Multimeter
15
1. Set the function switch to the V DC/AC ( ) position and use the MODE button to
select AC or DC.
2. Insert the black test lead plug into the “COM” terminal and the red test lead plug into
the “V” terminal.
3. Touch the test probe tips to the circuit under test. Be sure to observe the correct polar-
ity (red lead to positive, black lead to negative). Range switching and DC/AC selection
are automatic.
The probe tips may not be long enough to contact the live parts inside some xtures
because the contacts are deeply recessed. The reading may show 0 volts when the
outlet actually has voltage on it. Make sure the probe tips are touching metal contacts
before assuming that no voltage is present.
4. Read the voltage in the display. The display will indicate the proper value with decimal
point and symbol (DC/AC andV). If the polarity is reversed, the display will show minus
(-) before the value.
DC/AC Current Measurement
WARNING To reduce risk of electric shock, do not measure AC current on any circuit
whose voltage exceeds 250V AC. When measuring current, turn o the circuit power before
connecting the meter in series with the circuit. Improper set up could result in electrical
shock.
1. For current measurement up to 4000 µA, set the function switch to the µA ( )
position and insert the red test lead plug into the“µA / mA”terminal.
2. For current measurement up to 400 mA, set the function switch to the mA ( )
range and insert the red test lead plug into the “µA / mA” terminal.
3. For current measurement up to 10 A, set the function switch to the A ( ) position
and insert the red test lead plug into the“10 A” terminal.
4. Press MODE button to select DC or AC.
5. Insert the black test lead plug into the“COM” terminal.
6. Remove power from the circuit under test, then open up the circuit at the point where
you wish to measure current.
7. Touch the black test probe tip to the negative side of the circuit. Touch the red test
probe tip to the positive side of the circuit.
NOTICE Do not make current measurement on the 10 A scale for longer than 30 seconds.
Exceeding 30 seconds may cause damage to the meter and/or the test leads.
8. Apply power to the circuit.
9. Read the current in the display. The display will indicate the proper value with decimal
point and symbol.
Resistance Measurement
WARNING To reduce risk of electric shock, disconnect all power (remove batteries,
unplug cord, discharge all capacitors, etc.) to the circuit being measured before taking any
resistance measurement.
1. Set the function switch to Ω position.

micro DM-100 Digital Multimeter
16
2. Insert the black test lead plug into the “COM” terminal and the red test lead plug into
the “Ω” terminal.
3. Touch the test probe tips across the circuit or part under test. It is good practice to
disconnect one side of the part under test so the rest of the circuit will not interfere
with the resistance reading.
4. Read the resistance in the display. The display will indicate the proper value with deci-
mal point and symbol.
5. After resistance test, the capacitive circuits must be discharged. This will help protect
against electric shock.
DiodeTest
WARNING To reduce the risk of electric shock, do not test any diode that has voltage
on it.
1. Set the function switch to position.
2. Press the button until the symbol appears in the display.
3. Insert the black test lead plug into the “COM” terminal and the red test lead plug into
the “Ω” terminal.
4. Touch the test probe tips to the diode or semiconductor junction to test. Note the
meter reading.
5. Reverse the probe polarity by switching probe position. Note this reading.
6. The diode or junction can be evaluated as follows:
• If one reading shows a value and the other reading shows OL, the diode is good.
• If both readings show OL, the device is open.
• If both readings are very small or 0, the device is shorted.
NOTE! The value indicated in the display during the diode check is the forward voltage.
Continuity Check
WARNING To reduce risk of electric shock, never measure continuity on circuits or
wires that have voltage on them.
1. Set the function switch to position.
2. Insert the black test lead plug into the “COM” terminal and the red test lead plug into
the “Ω” terminal.
3. Press the button until the symbol appears on display screen.
4. Check meter operation by touching probe tips together. An audible signal should
sound.
5. Touch the test probe tips to the circuit or wire to check.
6. If the resistance is less than approximately 150 Ω, an audible signal will sound. The
display will also show the actual resistance.

micro DM-100 Digital Multimeter
17
Capacitance Measurement
WARNING To reduce risk of electric shock, disconnect all power (remove batteries,
unplug cord, discharge all capacitors, etc.) to the circuit being measured before taking any
capacitance measurement. Use the DC Voltage function to conrm that the capacitor is
discharged.
1. Set the function switch to CAP position. (“nF” and a small value will appear in the dis-
play).
2. Insert the black test lead plug into the “COM” terminal and the red test lead plug into
the “CAP” terminal.
3. Touch the test leads to the capacitor to be tested. The display will indicate the value,
proper decimal point and symbol.
Frequency Measurement
1. Set the function switch to Hz% position.
2. Insert the black test lead plug into the “COM” terminal and the red test lead plug into
the “F” terminal.
3. Touch the test probe tips to the circuit under test.
4. Read the frequency in the display. The digital reading will indicate the value, proper
decimal point and symbols (Hz, kHz).
Temperature Measurement
WARNING To reduce the risk of electric shock, disconnect both test probes from any
source of voltage before making a temperature measurement.
1. If you wish to measure temperature in °F, set the function switch to °F range. If you
wish to measure temperature in °C, set the function switch to °C range.
2. Insert the temperature adapter in “COM” and “V Ω CAP TEMP Hz” terminal with
–ve side in “COM” and +ve side in “V Ω CAP TEMP Hz” terminal.
Figure 8 – Temperature Probe
3. Insert the Temperature Probe into the adapter.
4. Touch the Temperature Probe head to the part
whose temperature is to be measured. Keep
the probe in contact with the part under test
until the reading stabilizes (about 30 seconds).
5. Read the temperature in the display. The digi-
tal reading will indicate the proper value with
decimal point.
WARNING To reduce risk of electric shock, be
sure the thermocouple has been removed before
changing to another measurement function.

micro DM-100 Digital Multimeter
18
Maintenance Instructions
WARNING
To reduce risk of electric shock, disconnect the test leads from any source of volt-
age before performing any maintenance activity.
Cleaning
• Do not immerse the multimeter in water. Wipe o dirt with a damp soft cloth. Do not use
aggressive cleaning agents or solutions. Gently clean the display screen with a clean dry
cloth. Avoid rubbing too hard.
• Use only alcohol swabs to clean the test lead connections.
Calibration
The calibration of the meter should be checked once a year to ensure that it performs ac-
cording to the specications. Take to a RIDGID Service Center for calibration check.
Fuse Replacement
If when measuring current the display shows zero, the fuse(s) may need to be changed.
Fuses
Back
of
Case
Figure 9 – Removing Back of
Multimeter Case
1. Switch o the multimeter.
2. Remove the battery (see “Changing/Install-
ing Battery”).
3. Loosen the 6 screws that hold the case to-
gether (see Figure 9) and remove back of
multimeter case.
4. Inspect fuses. If needed, remove fuse by gen-
tly pulling it out.
5. Install the new fuse into the holder. Always
use a fuse of the proper size and value.
(F500mA/1000V fast blow for the 400mA
range, F10A/1000V fast blow for the 10A
range – see Accessory section for catalog
numbers).
6. Carefully reassemble the multimeter ensuring seals are properly in place and are not
damaged. Do not operate without the case or battery cover secured.
Accessories
WARNING
To reduce the risk of serious injury, only use accessories specically designed and
recommended for use with the RIDGID DM-100 Digital Multimeter such as those
listed below. Other Accessories suitable for use with other tools may be hazardous
when used with this meter.
Catalog Number Description
44753 Test Leads with Covers, Black and Red
45023 Terminal Plugs
44758 K Type Adaptor and Temperature Probe