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3.6. TRANSISTOR 

TESTING

3.6.1.

Set the rotary switch to the hFE position.

3.6.2.

Determine whether the transistor to be tested in NPN or PNP type and locate the Emitter, Base and Collector leads. Insert leads of the transistor into

the correct holes in the transistor testing socket.

3.6.3.

The meter will show the approximate hFE value at test conditions of base current 10µA and Vce 3V.

3.7. 

CONTINUITY TEST

3.7.1.

Connect the black lead to the COM input socket and the red lead to the ºCV

mA input socket (the polarity of the red lead is ‘+’).

3.7.2.

Set the rotary switch to the       position and connect the test leads across the two points of the circuit under test. If continuity exists (i.e. resistance less 

than 50

) the built-in buzzer will sound.

3.8.

MEASURING TEMPERATURE

3.8.1.

Set the rotary switch to the 

O

C position and the LCD display will show the ambient temperature.

3.8.2.

Insert the red lead of the K-type thermocouple plug into the ºCV

mA input socket on the front panel and the black lead into the COM. Now touch the 

object to be measured with the thermocouple probe.

p  

WARNING!

To avoid electric shock, ensure that the thermocouple has been removed before changing to another function measurement.

5. MAINTENANCE

4. SPECIFICATION

6. DECLARATION OF CONFORMITY

p  

WARNING!

Before attempting to open the case, ensure that test leads have been disconnected from measurement circuits to avoid electric shock hazard.

5.1.

For continued protection against fire, replace fuse only with another of the same rating (F200mA/250V Quick Acting). Fuse is located under the circuit board. To 

gain access to the fuse, remove the protective rubber boot and the two screws from the rear of the meter. Lift off the rear cover, replace the fuse and re-assemble in

reverse order.

5.2.

If the battery sign           appears on the LCD display, it indicates that the battery should be replaced. Repeat the steps detailed in  

section 5.1 but replacing the battery (9V PP3) instead of the fuse. 

5.3.

SPARE PARTS

MM20.01

TEST LEADS FOR MM20

MM20.02

FUSE (0.5A) FOR MM20

MM20.03

PROBE FOR MM20

For Jack Sealey Ltd. Sole UK importer of Sealey Professional Tools.

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 equipment. 

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.

Sole UK Distributor,           

Sealey Group,

Bury St. Edmunds, Suffolk.

Declaration of Conformity  

We, the sole UK importer, declare that the product listed below is in conformity with the following standards and directives.

The construction file for this product is held by the Manufacturer and may be inspected,

by a national authority, upon request to Jack Sealey Ltd.

DIGITAL MULTIMETER

Model: MM20

89/336/EEC EMC Directive

73/23/EEC Low Voltage Directive

93/68/EEC CE Marking Directive

Signed by Mark Sweetman

22 November 2004

DC VOLTAGE

Range

Accuracy

Resolution

200mV

±0.5% of reading ±2 digits

0.1mV

2V

±0.5% of reading ±2 digits

1mV  

20V

±0.5% of reading ±2 digits

10mV

200V

±0.5% of reading ±2 digits

0.1V

600V

±0.8% of reading ±2 digits

1V

Input impedance:

10M

for all ranges.

AC VOLTAGE

Range

Accuracy             Resolution

200V

±1.2% of rdg ± 10 digits

100mV

600V

±1.2% of rdg ± 10 digits

1V

Overload protection: 600V dc or rms. ac for all 

ranges.

Frequency range: 40Hz - 400Hz

Response: Average calibrated in rms sine wave.

RESISTANCE

Range

Accuracy                Resolution

200

±0.8% of reading ±3 digits

0.1

2k

±0.8% of reading ±2 digit

1

20k

±0.8% of reading ±2 digit

10

200k

±0.8% of reading ±2 digit

100

2M

±1.0% of reading ±2 digit

1k

Maximum open circuit voltage: 3.2V

Overload protection: 250V dc or rms. as for all 

ranges

DC CURRENT

Range

Accuracy

Resolution

2mA

±1.5% of reading ±1 digit

1µA

20mA

±2.0% of reading ±5 digits

10µA

200mA

±1.5% of reading ±1 digits

0.1mA

10A

±2.0% of reading ±5 digits

10mA

Overload protection: F200mA/250V fuse

10A range unfused

Range

Accuracy

Resolution

4.1.

Accuracy Calculation

Example: Test reading on 200Vdc range is 56.4V. Accuracy is ±0.5% of reading ±2 digit.

Reading ±2 digit = 56.4 ±2 on the last figure i.e. 56.2 to 56.6V.

±0.5% on this range gives 56.2 - 0.5% to 56.6 + 0.5% or 55.9 to 56.9V. Therefore the actual voltage lies between 55.9 and 56.9V.

Note:

Accuracy is specified for a period of one year after calibration and at 18

O

C to 28

O

C with a relative humidity of 80%.

-20° to 0°C  0° to 400°C   400°C to 1000°C 

1°C

-20°C

to

1000°C

± 10.0%

of rdg ± 2

digits   

± 1.0% of

rdg ± 3 

digits

± 2.0% of rdg

TEMPERATURE

TRANSISTOR hFE TEST (0-1000)

Range

Test Range Test Current

Test Voltage         

NPN & PNP

0-1000

1b=10

µA

Vce=3V

01284 757500

sales@sealey.co.uk

www.sealey.co.uk

01284 703534

e-mail

Web

MM20 - 1 - 221104

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