Sealey MM18 User manual

1.1. PERSONAL PRECAUTIONS
When using this multimeter, please observe all normal safety rules concerning:
Protection against the dangers of electrical current.
Protection of the meter against misuse.
Full compliance with safety standards can only be guaranteed if used with the test leads supplied. If necessary, they must
be replaced with genuine Sealey leads with the same electrical ratings. Failure to do so will invalidate the warranty.
DO NOT use leads if damaged or if the wires are bared in any way.
1.2. GENERAL SAFETY INSTRUCTIONS
Familiarise yourself with the application and limitations of the multimeter as well as the potential hazards.
IF IN ANY DOUBT CONSULT A QUALIFIED ELECTRICIAN.
USE EXTREME CAUTION when working with high voltages.
 DO NOT use the meter if it is damaged. Before you use it inspect the case. Pay particular attention to the insulation
surrounding the connectors.
Inspect the test leads for damaged insulation or exposed metal. Check the test leads for continuity. Replace damaged test
leads before you use the meter.
 DO NOT use the meter if it operates abnormally. Protection may be impaired. When in doubt have the meter inspected by
your Sealey Authorised Dealer.
 DO NOT operate the meter where explosive gas, vapour or dust is present.
 DO NOT apply more than the rated voltage, as marked on the meter, between the probes or between any probe and earth
ground.
 Before use verify the meter's operation by measuring a known voltage.
 When measuring current, turn off circuit power before connecting the meter in the circuit. Remember to place the meter in
series with the circuit.
 WARNING Use caution when working with voltage above 30V ac rms, 42V peak, or 60V dc. Such voltages pose a shock
hazard.
 When using the probes keep your fingers behind the finger guards.
 When making connections, connect the black test lead before you connect the red test lead. When you disconnect the test
leads, disconnect the red one first.
 Remove the test leads from the circuit under test before you open the back cover.
 DO NOT operate the meter with the back cover removed or loosened.
 To avoid false readings, which could lead to possible electric shock or personal injury, replace the button cells as soon as
the low battery indicator ( ) appears.
 DO NOT touch any naked conductor with your hand or skin, to avoid electric shock, DO NOT ground yourself whilst
using the meter.
 When a probe is connected to a dangerous live potential, it must be noted that this potential can occur at the other probe.
NOTE CAT II measurement category is for measurements performed on circuits directly connected to low voltage
installations. (Examples are measurements on household appliances, portable tools and similar equipment.) DO NOT use
the meter for measurements within Measurement Categories III and IV.
 Disconnect circuit power and discharge all capacitors before testing resistance, diode or continuity.
 Use the proper function for your measurements.
 Before measuring current, check the meter's fuse and turn off power to the circuit before connecting the meter to the
circuit.
 Before moving the function switch or rotating the range switch, disconnect the test leads from the circuit under test.
The user shall ensure that test probes are correctly selected in order to prevent danger. Probes shall be selected
to ensure that adequate barriers guard against inadvertent hand contact with live conductors under test and that
probes have minimal exposed probe tips. Where there is a risk of the probe tip short circuiting with other live
conductors under test, it is recommended that the exposed tip length shall not exceed 4mm.
NOTE:The warnings, cautions and instructions referred to in this manual cannot cover all possible conditions and
situations that may occur. It must be understood that common sense and caution are factors which cannot be
built into this product, but must be applied by the operator.
INSTRUCTIONS FOR:
POCKET MULTIMETER
Model No: MM18
Thank you for purchasing a Sealey product. Manufactured to a high standard this product will, if used according to these instructions and
properly maintained, give you years of trouble free performance.
1. SAFETY INSTRUCTIONS
IMPORTANT: PLEASE READ THESE INSTRUCTIONS CAREFULLY. NOTE THE SAFE OPERATIONAL REQUIREMENTS, WARNINGS & CAUTIONS. USE THE
PRODUCT CORRECTLY AND WITH CARE FOR THE PURPOSE FOR WHICH IT IS INTENDED. FAILURE TO DO SO MAY CAUSE DAMAGE AND/OR PERSONAL
INJURY AND WILL INVALIDATE THE WARRANTY. PLEASE KEEP THESE INSTRUCTIONS SAFE FOR FUTURE USE.
Original Language Version MM18 Issue No:2(I)-09/09/14
© Jack Sealey Limited
1.3. ELECTRICAL SYMBOLS
Alternating Current.
Direct Current.
Both direct and alternating current.
Caution risk of danger refer to operating manual
before use.
Caution risk of electric shock.
Earth (ground) terminal.
Fuse.
The equipment is protected throughout by double
insulation or reinforced insulation.

Handy compact unit, small enough to fit in your pocket, making it
ideal for basic circuit testing on the move. Features flip lid for
added screen protection and storage of leads. Conforms to
EN 61010-1 CAT II safety requirements. Supplied with test
leads.
Measures:
• AC and DC Voltage
• DC Current
• Resistance
• Audible Continuity
2. FEATURES
© Jack Sealey Limited
3. SPECIFICATION
Model No: ......................... MM18
Measures:
Voltage DC: ...................... 2V, 20V, 200V, 250V (±1.0%)
Voltage AC:....................... 250V (±1.2%)
Current DC: ...................... 200mA (±1.2%)
Resistance:....................... 2k Ω, 20k Ω, 200k Ω, 2000k Ω (±1.2%)
Continuity Audible:............ Yes
Digits x Height: ................ 5 x 11mm
Batteries (Supplied):......... 2 x 1.5V
Size (L x W x H):............... 114 x 56 x 23mm
Weight: ............................. 101g
Conformity: ....................... EN 61010-1
Operation Environment:.... 0°C to 40°C
Relative Humidity:............. <75%
Storage Temperature:....... -10°C to 50°C
Relative Humidity:............. <85%
1. Display
3½ digit LCD, with a max. reading of 1999.
2. Function
Used to select desired function.
3. Range Switch
Used to select desired range.
4. Test Probes
DC VOLTAGE
Range Resolution Accuracy
2V 0.001V
20V 0.01V
200V 0.1V ±(1.0% +5 digits)
250V 1V
Input Impedance: 1MΩ
Max. Allowable Input Voltage: 250V dc
AC VOLTAGE
Range Resolution Accuracy
200V 0.1V
250V 1V ±(1.2% +10 digits)
Input Impedance: About 500kΩ
Frequency Range: 40Hz to 400Hz
Max. Allowable Input Voltage: 250V ac rms
Response: Average, calibrated
in rms of sine wave
DC CURRENT
Range Resolution Accuracy
200mA 0.1mA ±(1.2% + 5 digits)
Overload Protection: 250mA/250V Fast fuse
RESISTANCE
Range Resolution Accuracy
2kΩ 0.001kΩ
20kΩ 0.01kΩ
200kΩ 0.1kΩ ±(1.2% +5 digits)
2000kΩ 1kΩ
Max Open Circuit Voltage: About 0.4V
Overload Protection: 250V DC/AC rms
Original Language Version MM18 Issue No:2(I)-09/09/14

© Jack Sealey Limited
DIODE AND CONTINUITY
Range Description Remark
The display shows the approx. forward Open Circuit Voltage
voltage drop of the diode. about 2.5V
Max. Test Current:
1mA
The built in buzzer will sound if the
resistance is less than about 30Ω.
The buzzer may not sound if the Open Circuit Voltage
resistance is between 30Ω and 100Ω. about 2.5V
The buzzer will not sound if the
resistance is more than 100Ω.
Overload Protection: 250V DC/AC rms
Original Language Version MM18 Issue No:2(I)-09/09/14

4. OPERATING INSTRUCTIONS
4.1. MEASURING DC VOLTAGE
4.1.1. Set the function switch to the Vposition.
4.1.2. Set the range to the desired position. If the magnitude of the voltage to be measured is not known beforehand, set the range
switch to the highest range rst and then reduce it range by range until satisfactory resolution is obtained.
4.1.3. Connect the test leads across the source or circuit to be tested.
4.1.4. Read the reading on the display. The polarity of the red test lead connection will be indicated as well.
NOTE To avoid electric shock to you or damage to the meter, DO NOT measure a voltage higher than 250V.
4.2. MEASURING AC VOLTAGE
4.2.1. Set the function switch to the V position.
4.2.2. Set the range switch to 250V or 200V range position.
4.2.3. If the magnitude of the voltage to be measured is not known beforehand, set the range to the highest rst and then reduce it
until a satisfactory resolution is obtained.
4.2.4. Read the reading on the display.
NOTE To avoid electric shock to you or damage to the meter, DO NOT measure a voltage higher than 250V.
4.3. MEASURING DC CURRENT
4.3.1. Set the function switch to Aposition.
4.3.2. Set the range switch to the 200mA range position.
4.3.3. Turn off the circuit to be tested. Then discharge all capacitors.
4.3.4. Break the circuit path to be tested, then connect the test leads in series with the circuit.
4.3.5. Turn on the power to the circuit, then read the reading on the display. The polarity of the red test lead connection will be
indicated as well.
4.4. MEASURING RESISTANCE
4.4.1. Set the function switch to position.
4.4.2. Set the range switch to the desired resistance measuring range position.
4.4.3. Connect the test leads across the object to be measured.
4.4.4. Read the reading on the display.
NOTE:
1. For measurements > 1MΩ, the meter may take a few seconds to stabilise a reading. This is normal for high resistance
measurements.
2. When the test leads are in open circuit state , “1” will be dsplayed as an overrange indication.
3. Before measurement, disconnect all power to the circuit to be tested and discharge all capacitors thoroughly.
4.5. DIODE TEST
4.5.1. Set the function to the position.
4.5.2. Set the range switch to the position.
4.5.3. Connect the red test lead to the anode of the diode to be tested and the black lead to the cathode of the diode.
4.5.4. The display shows the approximate forward voltage drop of the diode. If the connection is reversed, “1” will be shown on the
display.
4.6. CONTINUITY TEST
4.6.1. Set the function switch to the position.
4.6.2. Set the range switch to the position.
4.6.3. Connect the test leads across the circuit to be tested.
4.6.4. If the resistance is less than about 30Ω, the built in buzzer will sound.
NOTE Before test, disconnect all power to the circuit to be tested and discharge all capacitors thoroughly.
© Jack Sealey Limited
5. MAINTENANCE
5.1. Periodically wipe the case with a damp cloth and mild detergent. DO NOT use abrasives or solvents.
5.2. BATTERY AND FUSE REPLACEMENT
5.2.1. When the symbol ” “ appears on the display, the batteries are low and must be replaced immediately. To replace the
batteries remove the screws in the back cover and remove the back cover. Remove the batteries and replace with batteries
of the same type (1.5V button cell LR44 or equivalent). Make sure the polarity connections are correct (see the indication on
the bottom of each cell compartment). Reinstall the back cover and its screws.
The fuse rarely needs to be replaced and is blown as a result of operator’s error. To replace the fuse, remove the back cover
(see above) replace the fuse with one of the same rating. Reinstall the back cover and its screws.
This meter uses 250mA/250V, fast, Ø5x20mm fuse.
 WARNING Remove all leads from the circuit under test before opening the back cover.
Original Language Version MM18 Issue No:2(I)-09/09/14

[e-mail]
www.sealey.co.uk
NOTE: It is our policy to continually improve products and as such we reserve the right to alter data, specifications and component parts without prior notice.
IMPORTANT: No liability is accepted for incorrect use of this product.
WARRANTY: Guarantee is 12 months from purchase date, proof of which will be required for any claim.
INFORMATION: For a copy of our latest catalogue and promotions call us on 01284 757525 and leave your full name and address, including postcode.
01284 757500
01284 703534
Sole UK Distributor, Sealey Group,
Kempson Way, Suffolk Business Park,
Bury St. Edmunds, Suffolk,
IP32 7AR
© Jack Sealey Limited
Environmental Protection.
Recycle unwanted materials instead of disposing of them as waste. All tools, accessories and packaging should
be sorted, taken to a recycle centre and disposed of in a manner which is compatible with the environment.
WEEE Regulations.
Dispose of this product at the end of its working life in compliance with the EU Directive on Waste Electrical
and Electronic Equipment. When the product is no longer required, it must be disposed of in an environmentally
protective way. Contact your local solid waste authority for recycling information.
Battery Removal.
WARNING! To avoid electric shock, disconnect the test leads from any source of voltage before
removing the battery door.
Disconnect the test leads from the meter.
Open the battery cover by loosening the two cover screws using a cross head screwdriver (see picture
below and refer to 5.2.1. above).
Replace the battery cover back in place. Secure with the screws.
 WARNING! To avoid electric shock, do not operate the meter until the battery cover is in place and
fastened securely.
Dispose of batteries according to local authority guidelines.
Under the Waste Batteries and Accumulators Regulations 2009, Jack Sealey Ltd are required to
inform potential purchasers of products containing batteries (as defined within these regulations),
Jack Sealey Ltd’s Batteries Producer Registration Number (BPRN)
is BPRN00705.
Original Language Version MM18 Issue No:2(I)-09/09/14