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ROLLS DIGITAL MULTIMETER 

MU118 OPERATION MANUAL 

1. INTRODUCTION   

This instrument is compact, rugged, battery operated, handheld 3 

1

/2 digit digital multimeter for measuring DC and AC voltage, DC 

and AC current, resistance and diode, capacitance, transistor, 
continuity test, temperature and frequency.   
The dual–slope A-D converter uses C-MOS technology for 
auto-zeroing, polarity selection and over-range indication. Full 
overload protection is provided. It is an ideal instrument for use in 
the field, laboratory, workshop, hobby and home applications.   

 

2. FEATURES   

* Push-button ON-OFF power switch. 

 

* Single 30 position easy to use rotary switch for function and range         

selection.  

     

* High sensitivity of 100µV.   
* Automatic over range indication with the “1” displayed.   
* Automatic polarity indication on DC range.   
* All ranges fully protected.   
* Resistance measurements 0.1

 to 200M

.  

* Capacitance measurements 1pF to 20µF.   
* Diode testing with 1mA fixed current.   
* Transistor hFE test with Ib

100µA.  

* Temperature measurement with or without K type thermocouple.   

 

3. SPECIFICATIONS   
Accuracies are ± (% r No. of digits)   
Operating environment: 23±5

, less than 75% R.H.   

DC Voltage   

Range  

Accuracy  

Resolution  

200mV  

±(0.5% of rdg + 3d)   

100

μ

V  

2V  

1mV  

20V  

10mV  

200V  

100mV  

1000V   

±(0.8% of rdg + 3d)   

1V   

Input impedance: 10M ohm on all ranges.   
Overload Protection: 1000V DC or peak AC on all ranges.   

 

AC Voltage   

Range  

Accuracy  

Resolution  

2V  

±(0.8% of rdg + 3d)   

1mV  

20V  

10mV  

200V  

100mV  

750V   

±(1.2% of rdg + 5d)   

1V   

Input impedance: 10M

 on all ranges   

Frequency range: 40Hz to 400Hz.   
Overload protection: 700V rms or 1000V peak continuous on ac 
ranges, except 200mV ac range (15 seconds maximum above 
300V rms).   
Indication: Average (rms of sine wave)   

 

DC Current   

Range  

Accuracy  

Resolution  

20mA   

±(0.8% of rdg + 2d)   

10

μ

A  

200mA   

±(1.2% of rdg + 2d)   

100

μ

A  

10A  

±(2% of rdg + 5d)  

10mA  

Overload protection: 0.2A/250V fuse. (20A range not fused) 
Maximum input current: 20A, 15 sec. max.   

 

AC Current   

Range  

Accuracy  

Resolution  

20mA   

±(1% of rdg + 3d)   

10

μ

A  

200mA   

±(1.8% of rdg + 3d)   

100

μ

A  

10A  

±(3% of rdg + 7d)  

10mA  

Overload protection: 0.2A/250V fuse. (20A range not fused.)   
Frequency range: 40Hz to 400Hz. 
Maximum input current: 10A, 15 sec. max. 
Indication: Average (rms of sine wave)

 

Resistance  

Range   Accuracy 

Resolution  

200

   

±0.8% of rdg ± 3d   

0.1

   

2k

 

±0.8% of rdg ± 2d   

  1

   

20k

  

10

   

200k

  

100

   

2M

  

1k

   

20M

   

±1% of rdg ± 5d   

10k

   

200M

 

±[5% of (rdg -1M

) +10d]   

10k

   

On 200M

range, if short the two test leads, display reading is 10 

digits should be subtracted from measurement results.   

 

Capacitance  

Range Accuracy 

 

Resolution 

 

2nF 

±(3% of rdg + 5d)   
 

 1pF  

20nF  

10pF 

 

200nF 100pF 

 

2µF  

1nF 

 

20µF  

10nF  

 

Temperature  

Range  

Accuracy  

Resolutio
n  

 

-50~400

   

±(1.2% of rdg + 4d)   

1

   

400~1000

   

±(1.9% of rdg + 15d)   

1

   

*Using K type thermocouple probe.   

 

Frequency Test   

 

Overload protection: AC 220V rms.   

 

4. 

GENERAL CHARACTERISTICS

   

Maximum display: 1999 counts (3

1

/2 digits) with automatic polarity 

indication and eng. unit. 
Indication method: LCD display. 
Measuring method: Dual-slope integration A-D converter system. 
Overrange indication: “1” or “-1” figure only in the display. 
Maximum common mode voltage: 500V DC/AC rms.   
Reading rate: 2~3 reading per sec. (approximate).   
Temperature for guaranteed accuracy: 23±5

.  

Temperature ranges: Operating: 0

 to 40

 (32

 to 104

)  

 Storage: -10

 to 50

 (14

 to 122

)  

Power supply: One 9V battery (NEDA 1604 or 6F22 or equivalent).   
Low battery indication: 

to lift of display. 

Size: 88 (W) × 170 (D) × 38(H) mm. 
Weight: 340g (including battery)   
Accessories: Operating manual, set of test leads and thermocouple 
(K type, 300

)  

 

5.

 OPERATION

   

1. Check the 9-volt battery by setting the ON-OFF switch to ON. If the 

battery is weak, a 

  sign will appear on the display. It is does not 

appear on the display, proceed as below. See maintenance if the 
battery has to be replaced.   

2. The mark or sign 

next to the test lead jacks is for warning that 

the input voltage or current should not exceed the indicated 
values. This is to prevent damage to the internal circuit.   

3. The function switch should be set to the range which you want to 

test before operation.   

4. If the voltage or current range is not known beforehand set the 

function switch to a high range and work down.   

5. When only the figure “1” is displayed, over-range is being indicated 

and the function switch must be set to a higher range.   

 

5.1) DC Voltage Measurement   
1, Connect the BLACK test lead to the COM jack and the RED test 

lead to the V/

 jack.   

2. Set the FUNCTION switch to the “V

range to be used and 

connect the test leads across the source or load under 
measurement. The polarity of the RED lead connection will be 
indicated at the same time as the voltage.   

” 

NOTE:  

Do not apply more than 1000V to the input, Indication is 

possible at higher voltages but there is danger of damaging the 

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