APPA 91 User guide

DIGITAL MULTIMETER





OPERATOR’S MANUAL

APPA 91

 WARNING

THESE SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL ONLY. TO AVOID
ELECTRIC SHOCK, DO NOT PERFORM ANY SERVICING OTHER THAN THAT CONTAINED IN THE
OPERATING INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO SO.
Also, the complete duty cycle for the 20A measurement should be stated as on for 30 seconds max, and off for
3 minutes min.

1

INTRODUCTION

1-1 Unpacking and Inspection

Upon removing your new Digital Multimeter from its packing, you should have the following items:

1. Digital Multimeter.

2. Test lead set (one black, one red).

3. Operators Manual.

4. Protective holster.

1-2 Meter Safety

Terms marked on Equipment

 ATTENTION — Refer to Manual.
 DOUBLE INSULATION — Protection Class II.
 DANGER — Risk of electric shock

2

Symbols in this Manual

 This symbol indicates where cautionary or other information is found in the manual.
 Fuse



Battery

1-3 Front Panel

Refer to Figure 1 and the following numbered steps to familiarize yourself with the meter's front panel controls and
connectors.

1. Digital Display — The digital display has a 3-1/2 LCD readout (maximum reading 1999) with automatic polarity,
overrange and low battery indicators.

2. Rotary Switch — Select the Function and Range desired.

3. COM Input Terminal — Ground input connector.

4. V Ω

: Input Terminal — Positive input connector for Volts, Ohms and Diode.

5. mA µA Input Terminal — Positive input connector for mA and µA measurements (up to 200mA).

6. 20A Input Terminal — Positive input connector for Amp measurements (up to 20A).

3

1

2

Figure 1

4

4

3

5

6

SPECIFICATIONS

2-1 General Specifications
Display : 3-1/2 digit Liquid Crystal Display (LCD) with a maximum reading of 1999.
Polarity Indication : Automatic, positive implied, negative indicated.
Zero Adjustment : Automatic.
Overrange Indication : "1" or "-1".

Low Battery Indication: "" is displayed when the battery voltage drops below operating voltage.
Measuring Rate: 2.5 times per second, nominal.

Auto Power Off: Approx. 30 minutes.
Temperature Coefficient : 0.15 x (Specified accuracy) / °C, <18°C or >28°C.
Power Requirements : Standard 9V battery, NEDA 1604, JIS 006P, IEC 6LF22.
Battery Life : Alkaline 300 hours.

5

Dimensions (WxHxD) : 84mm x 175mm x 31mm, without holster
95mm x 192 mm x 50 mm, with holster.
Weight (including battery) : 340 gms, with out h ols ter
550 gms, with holster.

Accessories : Protective Holster, Battery (installed) and Instruction Manual.
2-2 Env ir onm e nt al C ond i ti ons :

Indoor use.
Maximum Altitude : 2000m

Installation Category : IEC 1010 CAT .

CAT.Ⅱ is for measurements performed on circuits directly connected to the low-voltage installation
CAT .Ⅲ. is for measurements per formed in the building installation.

Pollution Degree : 2
Operating Temperature : 0°C to 45°C (below 75% R.H.)
Storage Temperature : -20°C to 60°C (below 80%R.H.)

Ⅱ. 1000V, 600V CAT .Ⅲ.

6

.

2-3 Electrical Specifications

Accuracy is ± (% reading + number of digits) at 23°C ± 5°C, less than 75% R.H.

(1) DC Volts

Range Resolution Accuracy

200mV 100 µV

2V 1mV
20V 10mV

±(0.5%rdg + 1dgt)

200V 100mV

1000V 1V

Input Impedance : 10MΩ.

7

Over voltage

protection

DC 500V / AC 350V

DC 1200V

AC 850V

(2) AC Volts

Range Resolution Accuracy

200mV 100 µV

2V 1mV
20V 10mV
200V 100mV
750V 1V

Input Impedance : 10MΩ, less than 100pF

±(1.25%rdg + 4dgt)

40Hz — 500Hz

8

Over voltage

protection

DC 500V / AC 350V

DC 1200V

AC 850V

(3) DC Current

Range Resolution Accuracy Voltage Burden

200 µA 0.1 µA
2mA 1 µA
20mA 10 µA

±(1.0% rdg + 1dgt)

200mA 100 µA

20A 10mA ±(2.0%rdg + 3 dgt)

* 20A Range : 30 seconds maximum above 10A.
Overload Protection : 1A/500V fast blow fuse for mA, µA input.

16A/500V fast blow fuse for 20A input.

9

600mV max.

900mV max.

(4) AC Current

Range Resolution Accuracy Voltage Burden

200 µA 0.1 µA
2mA 1 µA
20mA 10 µA
200mA 100 µA

* 20A 10mA

* 20A Range : 30 seconds maximum above 10A.
Overload Protection : 1A/500V fast blow fuse for mA, µA input.

16A/500V fast blow fuse for 20A input.

±(1.5% rdg + 3 dgt)

40Hz — 500Hz

±(2.5% rdg + 3 dgt)

40Hz — 500Hz

10

600mV rms max.

900mV rms max.

(5) Resistance

Range Resolution Accuracy

200Ω 0.1Ω

2KΩ 1Ω
20KΩ 10Ω
200KΩ 100Ω

2MΩ 1KΩ

20MΩ 10KΩ

Overload Protection : 500V d.c/a.c max.

Max.Test

Current

Max.Open

Circuit Voltage

±(0.75% rdg + 4 dgt) 2.5mA 3.2V

200 µA
40 µA

±(0.75% rdg + 1 dgt)

4 µA

0.5V

400nA

±(1.5% rdg + 5 dgt) 40nA

11

(6) Diode Check

Range Resolution Accuracy



* Overload Protection: 500V d.c/a.c max.

Instant Continuity Description:

Built – in buzzer sound when resistance is less than 50Ω.

(7) Auto Power Off:

The meter will automatically shut itself off after approximately 30 minutes when the rotary switch is not changed.
The meter can be turned back on by switching to another range.

(8) Beep Guard
The beeper will sound if the test lead is connected to the mA/µA (20A) input terminal while the rotary function

selector is not in mA/µA (20A) position. There is no beep guard at 20mA/20A range of DC and AC function.

1mV ±(1.5% rdg+ 5 dgt) 1.5mA 3.2V

12

Max.Test

Current

Max.Open

Circuit voltage

OPERATION

This instrument has been designed and tested in accordance with IEC Publication 1010, Safety Requirements of
Electronic Measuring Apparatus and has been supplied in a safe condition. This instruction manual contains some
information and warnings which have to be followed by the user to ensure safe operation and to retain the
instrument in safe condition.

3-1 Precautions and Preparations for measurement

1. Make sure that the battery is properly connected.

2. The instrument should only be operated between 0°C ~ 50°C and at less than 75% R.H.

3. Do not use or store this instrument in a high temperature or high humidity environment and do not store the unit in
direct sunlight.

4. Do not replace battery with power on condition.

5. If the unit is not to be used for a log period of time , remove the battery.

6. Do not forget to turn off after use.

7. If the meter is used near equipment that generates electro-magnetic interence, the display may be unstable or indicate
incorrect measurement values.

8.

 Maximum rated voltage to earth for voltage and current measurements terminals is 1000V AC/DC Cat.II.

13

3-2 Voltage Measurements

1. Set the rotary switch at the required position.

2. Connect black test lead to "COM" terminal and red lead to "VΩ

3. Connect test leads to measuring points and read the display value.

3-3 Current Measurements

1. Set the rotary switch to the required position.

2. Connect black test lead to "COM" terminal.

3. Connect red test lead to "mA/µA" terminal for measurement up to 200mA.
For measuring current between 200mA and 20A, connect test lead to "20A" terminal.

4. Connect test leads to measuring points and read the display value.

14

:" input terminal.

3-4 Resistance Measurement

1. Set the rotary switch to the required position.

2. Connect black test lead to "COM" terminal and read lead to "VΩ

3. Connect test leads to measuring points and read the display value.

3-5 Diode Check

1. Set the rotary switch to the "

2. Connect the black test lead to the "COM" terminal and the red test lead to the "VΩ

3. Connect the test lead to the diode. Normally the forward voltage drop of good silicon diode is shown
between .500V and .900V. If the diode under test is defective, "000" (short circuit) or "1" (non-conductance) is
displayed. Reverse check of diode: If the diode under test is good "1" is displayed. If the diode under test is
defective "000" or other values are displayed.

:" position.

15

:" input terminal.

:" input terminal.

3-6 Continuity Check by sounder

1. Set the rotary switch at the "

2. Connect the black test lead to "COM" terminal and the red test lead to "VΩ

3. Connect test leads to the circuit under test.

4. Built-in sounder operates if the resistance in the circuit under test is below 50Ω.

:" position.

:" input terminal.

MAINTENANCE

 WARNING

TO AVOID ELECTRICAL SHOCK REMOVE TEST LEAD BEFORE OPENING THE COVER.

4-1 General Maintenance

1. Repairs or servicing not coveted in this manual should only be performed by qualified personal.

2. Periodically wipe the case with a dry cloth and detergent do not use abrasives or solvents.

16

4-2 BATTERY INSTALLATION OR REPLACEMENT

The meter is powered by a single 9V batter y. Refer to Figur e 2A and use the f ollowing procedure to replace the
battery:

1. Disconnect the test leads and turn the meter off. Remove the test leads from the front terminals.

2. Position the meter face down. Remove the three screws from the case bottom.

3. Lift the end of the case bottom gently until it unsnaps from the case top at the end nearest the LCD.

4. Lift the battery from the case top, and carefully disconnect the battery from battery connector leads.

5. Fit the battery connector leads to the terminals of a new battery and reinsert the battery into the case top. Make
sure that the battery leads to not become pinched between the case bottom and case top.

6. Replace the case top and case bottom. Make sure that all gaskets are properly seated and the two snaps on the
case top are engaged. Reinstall the three screws.

17

4-3 FUSE REPLACEMENT

Refer to Figure 2B and use the following procedure to examine or replace the meter's fuse:

1. Perform steps 1 through 3 of the battery replacement procedure.

2. Lift the circuit board from the case top. Do not remove the screws from the circuit board.

3. Remove the defective fuse by gently prying one end of the fuse loose and sliding the fuse out of the fuse holder.

4. Install a new fuse of the same size and rating. Make sure the new fuse is centered in the fuse holder.

5. Make sure that the case top rotary switch and circuit board switch both are in the OFF position.

6. Replace the case top and case bottom. Make sure that all gaskets are properly seated and the battery leads do
not become pinched between the case halves, and the two snaps on the case top are engaged. Reinstall the
three screws.

18

Battery Replacement

Case Bottom

Fuse 2

9V Battery

Case Top

Battery Connector

Fuse 1

Figure 2A Figure 2B

19

HOW TO USE THE PROBE HOLDER

Clip one probe on the holster for
one handed meter operation.

Wrap the leads around the
holster to store the test probes.

20

HOW TO USE THE TILT STAND AND HOLSTER

Swing the stand out for easier meter reading. Swing the upper holder out and hook it over a door.

21

HOW TO USE THE TILT STAND AND HOLSTER

Meter in holster face down. Hang on a nail at the workbench

22

Copright  2001, APPA Tech., Corp. All rights reserved.

APPA TECHNOLOGY CORP.

9F.119-1 Pao-Zong Rd., Shin-Tien,

Taipai, 23115, Taiwan, R.O.C.

P.O.Box. 12-24 Shin-Tien, Taiwan.

Tel : [phone] Fax : [phone]

E-MAIL:info @appatech.com

http://www.appatech.com

Printed In Taiwan