Extech Instruments EX205T User manual

User Guide
True RMS Multimeter
Extech EX205T

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Introduction
Thank you for selecting the Extech EX205T True RMS Auto-ranging Multimeter. This meter measures
AC/DC Voltage, AC/DC Current, Resistance, Diode Test, and Continuity. Proper use and care of this
meter will provide many years of reliable service. Please visit the Extech Instruments website
(www.extech.com) to check for the latest version of this User Guide. Extech Instruments is an ISO-
9001 certified company.
Safety
This symbol adjacent to another symbol, terminal or operating device indicates
that the operator must refer to an explanation in the Operating Instructions to
avoid personal injury or damage to the meter.
This WARNING symbol indicates a potentially hazardous situation, which if not
avoided, could result in death or serious injury.
This CAUTION symbol indicates a potentially hazardous situation, which if not
avoided, may result damage to the product.
This symbol advises the user that the terminal(s) so marked must not be
connected to a circuit point at which the voltage with respect to earth ground
exceeds (in this case) 600 VAC or VDC.
This symbol adjacent to one or more terminals identifies them as being associated
with ranges that may, in normal use, be subjected to particularly hazardous
voltages. For maximum safety, the meter and its test leads should not be handled
when these terminals are energized.
This symbol indicates that a device is protected throughout by double insulation or
reinforced insulation.
PER IEC1010 OVERVOLTAGE INSTALLATION CATEGORY
OVERVOLTAGE CATEGORY I
Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in which
measures are taken to limit the transient overvoltages to an appropriate low level.
Note – Examples include protected electronic circuits.
OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be supplied from
the fixed installation.
Note – Examples include household, office, and laboratory appliances.
OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed installations.
Note – Examples include switches in the fixed installation and some equipment for industrial use
with permanent connection to the fixed installation.
OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of the installation.
Note – Examples include electricity meters and primary over-current protection equipment
WARNING
CAUTION
MAX
600V

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CAUTIONS
Improper use of this meter can cause damage, shock, injury or death. Read and understand
this user manual before operating the meter.
Always remove the test leads before replacing the battery or fuses.
Inspect the condition of the test leads and the meter itself for any damage before operating the
meter.
Use great care when making measurements if the voltages are greater than 25 VAC rms or 35
VDC. These voltages are considered a shock hazard.
Warning! This is a Class A device. This device can cause interference in residential areas.
Always discharge capacitors and remove power from the device under test before performing
Diode, Resistance or Continuity tests.
Voltage checks on electrical outlets can be difficult and misleading because of the uncertainty
of connection to the recessed electrical contacts. Other means should be used to ensure that
the terminals are not "live".
If the equipment is used in a manner not specified by the manufacturer, the protection provided
by the equipment may be impaired.
This device must not be used by children. It contains hazardous objects as well as small parts
that the children could swallow.
Do not leave batteries and packing material lying around unattended; they can be dangerous
to children.
In the event that this device will be stored for an extended period of time, remove the batteries.
Expired or damaged batteries can be hazardous to skin. Use suitable hand gloves in such
cases.
Do not short-circuit the battery.
Never dispose of batteries in a fire. Batteries may explode or leak.
Never mix battery types. Always install new batteries of the same type.

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SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be operated with caution. The rules listed below
must be carefully followed for safe operation.
1. NEVER apply voltage or current to the meter that exceeds the specified maximum:
Input Protection Limits
Function Maximum Input
V AC/DC, Resistance, Diode Test, Continuity 600 VDC/AC rms
μA or mA AC/DC 200mA fused
A AC/DC 10A fused
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input jack exceeds 600V above earth
ground.
4. NEVER connect the meter leads across a voltage source while the function switch is in the
current, resistance, or diode mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies and disconnect the power when making
resistance or diode tests.
6. ALWAYS turn off the power and disconnect the test leads before opening the covers to replace
the fuse or batteries.
7. NEVER operate the meter unless the back cover and the battery and fuse covers are in place
and fastened securely.
8. If the equipment is used in a manner not specified by the manufacturer, the protection provided
by the equipment may be impaired.

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Controls and Jacks
1. 2000 count LCD
2. MAX button
3. MODE button
4. FUNCTION switch
5. mA, µA and 10A input jacks
6. Backlight button
7. HOLD button
8. RANGE button
9. Positive input jack
10. COM input jack
Note: Tilt stand, test lead holders, and battery compartment are on rear of unit.
Symbols and Enunciators
Continuity
Diode test
µ micro (10-6) (amps)
m milli (10-3) (volts, amps)
A Amps
k kilo (103) (ohms)
M mega (106) (ohms)
 Ohms
V Volts
AC Alternating current
DC Direct current
MAX Maximum
AUTO Auto-ranging
HOLD Display hold

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Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are extremely dangerous
and should be measured with great care.
1. ALWAYS turn the function switch to the OFF position when the meter is not in use.
2. If “OL” appears in the display during a measurement, the value exceeds the range you have
selected. Change to a higher range.
AC/DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC voltages if a motor on the circuit is being switched ON or OFF.
Large voltage surges may occur that can damage the meter.
1. Rotate the function switch to the VAC or VDC position.
2. Insert the black test lead banana plug into the negative COM jack. Insert the red
test lead banana plug into the positive Vjack.
3. 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.
4. Read the voltage in the display.
AC/DC CURRENT MEASUREMENTS
1. Insert the black test lead banana plug into the negative COM jack.
2. Press the MODE button to indicate “DC” or “AC” on the display.
3. For current measurements up to 2000µA, set the function switch to the µA position
and insert the red test lead banana plug into the µA/mA jack.
4. For current measurements up to 200 mA DC, set the function switch to the mA
position and insert the red test lead banana plug into the µA/mA jack.
5. For current measurements up to 10A DC, set the function switch to the 10A position
and insert the red test lead banana plug into the 10A jack.
6. Connect the test leads in series with the circuit under test.
7. Apply power to the circuit.
8. Read the current in the display.

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RESISTANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to the unit under test and discharge all
capacitors before taking any resistance measurements. Remove the batteries and unplug the line
cords.
1. Rotate the function switch to the Ωposition.
2. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive jack.
3. Touch the test probe tips across the device under test.
4. Read the resistance in the display.
CONTINUITY CHECK
WARNING: To avoid electric shock, never measure continuity on circuits or wires that have a
voltage potential.
1. Rotate the function switch to the position.
2. Insert the black lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive jack.
3. Press the MODE button to indicate“ " on the display
4. Touch the test probe tips to the circuit or wire you wish to check.
5. If the resistance is less than the continuity threshold, the audible signal will sound.
DIODE TEST
1. Rotate the function switch to the green position.
2. Insert the black test lead banana plug into the negative COM jack and the red test
lead banana plug into the positive jack.
3. Press the MODE button to indicate “ “and “V” on the display.
4. Touch the test probes to the diode under test. Forward voltage will typically indicate
0.400 to 0.700V. Reverse voltage will indicate “OL”. Shorted devices will indicate
near 0V and an open device will indicate “OL” in both polarities.

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AUTORANGING/MANUAL RANGE SELECTION
When the meter is first switched on, it automatically enters the Auto-Ranging mode. This
automatically selects the best range for the measurements being made and is generally the best
mode for most measurements. For measurement situations requiring that a range be manually
selected, perform the following:
1. Press the RANGE button. The “AUTO” display indicator will turn off.
2. Press the RANGE key to step through the available ranges until the range desired is selected.
3. Press and hold the RANGE button for 2 seconds to exit manual ranging.
Note: Manual ranging does not apply to the Diode and Continuity functions.
MAX (MAXIMUM READING) MODE
1. Press the MAX button to activate the MAX mode. The display icon "MAX" will appear. The meter
will display and hold the maximum reading and will update only when a new maximum value is
detected.
2. Press the MAX button again to exit the mode.
Note: Max does not apply to the Resistance, Diode and Continuity functions.
DISPLAY BACKLIGHT
Press and hold the button for 2 second to turn the backlight on. The backlight will automatically
turn off after approximately 10 seconds or press and hold the button again for 2 seconds to
manually turn it off.
HOLD
The HOLD function freezes the reading in the display. Press the HOLD button momentarily to
activate or to exit the HOLD function.
Note: The HOLD button does not function in the IR measurement mode.
AUTO SLEEP
If no button is pressed the auto sleep feature will place the meter in sleep mode after approximately
15 minutes of operation. If this happens, press any button to wake the meter or switch the meter to
OFF if it no longer in use.

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Maintenance
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before
removing the back cover or the battery or fuse covers.
WARNING: To avoid electric shock, do not operate the meter until the battery and fuse covers are
in place and fastened securely.
This MultiMeter is designed to provide years of dependable service, if the following care instructions
are followed:
1. KEEP THE METER DRY. If it gets wet, wipe it off.
2. USE AND STORE THE METER IN NORMAL TEMPERATURES. Temperature extremes can
shorten the life of the electronic parts and distort or melt plastic parts.
3. HANDLE THE METER GENTLY AND CAREFULLY. Dropping it can damage the electronic parts
or the case.
4. KEEP THE METER CLEAN. Wipe the case occasionally with a damp cloth. DO NOT use
chemicals, cleaning solvents, or detergents.
5. USE ONLY FRESH BATTERIES OF THE RECOMMENDED SIZE AND TYPE. Remove old or
weak batteries so they do not leak and damage the unit.
6. IF THE METER IS TO BE STORED FOR A LONG PERIOD OF TIME, the batteries should be
removed to prevent damage to the unit.
BATTERY and FUSE Replacement
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before
removing the battery cover.
1. Turn power off and disconnect the test leads from the meter.
2. Open the rear battery/fuse compartment by removing the Phillips head screw on the lower rear of
the meter. .
3. Pull down on the cover to release the latch and then lift it off.
4. Remove the old battery or fuse and install a new one of the correct rating.
5. Place the battery/fuse cover back in place. Secure with the screw.
WARNING: To avoid electric shock, do not operate the meter until the battery cover is in place and
fastened securely.
NOTE: If the meter does not work properly, check the fuses and replace the battery to make sure that
they are still good and that they are properly inserted.
All EU users are legally bound by the Battery Ordinance to return all used batteries to
community collection points or wherever batteries / accumulators are sold!
Disposal in household trash or refuse is prohibited!
Disposal: Follow the valid legal stipulations in respect of the disposal of the device at the
end of its lifecycle

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Specifications
Function Range Resolution Accuracy
200 mV 0.1 mV (0.8% reading + 6 digits)
2V 0.001V
20V 0.01V (0.5% reading + 2 digits)
200V 0.1V
DC Voltage
600V 1V (0.8% reading + 2 digits)
200 mV 0.1 mV
2V 0.001V
20V 0.01V
200V 0.1V
600V 1V
(1.5% reading + 6 digits)
AC Voltage
50/60Hz
All AC voltage ranges are specified from 5% of range to 100% of range
200 A 0.1 A
2000 A 1 A
20 mA 0.01 mA
200 mA 0.1 mA
(1.5% reading + 5 digits)
2.000 0.001 A
10 A 0.01 A (2.5% reading + 5 digits)
DC Current
Note:10A for 30 sec max
200 A 0.1 A
2000 A 1 A
20 mA 0.01 mA
200 mA 0.1 mA
(1.5% reading + 8 digits)
2.000 0.001 A
10 A 0.01 A (3.0% reading + 5 digits)
AC Current
(50/60Hz)
Note: 10A for 30 sec max
200 0.1 (0.8% reading + 5 digits)
2 k0.001 k
20 k0.01 k
200 k0.1 k
(0.8% reading + 2 digits)
2 M0.001 M
Resistance
20 M0.01 M
(2.5% reading + 8 digits)
NOTE: Accuracy is stated at 18oC to 28oC (65oF to 83oF) and less than 75% RH.

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Enclosure Double molded
Diode Test Test current of 0.9mA maximum, open circuit voltage 2.8V DC typical
Continuity Threshold 20 to 50, test current <1.5mA
Input Impedance 10MΩVDC/VAC
AC Response True rms
ACV Bandwidth 40Hz to 1000Hz
Display 2,000 count backlit liquid crystal display
Over-range indication “OL” is displayed
Auto Power Off 15 minutes (approximately)
Polarity Automatic (no indication for positive); Minus (-) sign for negative
Measurement Rate 2 times per second, nominal
Battery One 9 volt (NEDA 1604) battery
Fuses mA, µA ranges; 200mA 250V ceramic fast blow
A range; 10A 600V ceramic fast blow
Operating Temperature -10ºC to 40ºC (14ºF to 122ºF)
Storage Temperature -10oC to 60oC (14oF to 140oF)
Operating Humidity Max 80% up to 31ºC (87ºF) decreasing linearly to 50% at 40ºC (104ºF)
Storage Humidity <80%
Operating Altitude 2000 meters (7000 ft) maximum
Weight 260g (9.17oz)
Size 147 x 76 x 42mm (5.8 x 2.9 x 1.6”)
Safety This meter is intended for origin of installation use and protected, against
the users, by double insulation per IEC/EN 61010-1:2001 and IEC/EN
61010-031:2002 to Category III 600V; Pollution Degree 2.
Approvals CE
Copyright ©2012 Extech Instruments Corporation (a FLIR company)
All rights reserved including the right of reproduction in whole or in part in any form.
ISO-9001 Certified
www.extech.com