twintex VC9901 Installation manual

3
1/2DIGITAL MULTIMETER OPERATION MANUAL
1.SPECIFICATIONS
1.1 GENERAL SPECIFICATIONS
Display :3
1/2 digit LCD with a max reading of 1999.
Polarity : Automatic negative polarity indication.
Zero adjustment : Automatic.
Over range indication : Only the MSD “1” displays.
Lowbattery :The“ ” displays.
Safety standards : EMC/LVD. The meter is up to the standards of
IEC1010 Pollution Degree 2, Over voltage categoryⅡor double insulationⅡ.
Operating environment : Temperature 32 to 104℉(0℃to 40℃), humidity<85%RH.
Storage environment : Temperature -4 to 140℉(-20℃to 60℃), humidity<95%RH.
Power : Single, standard 9 volt battery. NEDA1604IEC6F22
Dimension : 140(H)X65(W)X40(D)mm
Weight : Approx. 170g(including 9V battery)
1.2 ELECTRICAL SPECIFICATIONS
Accuracyis ±(percentage of reading + number of digit) at 23±5℃,<75%RH.
DC Voltage
Range Accuracy Resolution
200mV 100uV
2V 1mV
20V 10mV
200V
±(0.5%+3d)
100mV
1000V ±(0.8%+5d) 1V
Impedance：10MΩ
AC Voltage
Range Accuracy Resolution
20V 10mV
200V ±(0.8%+5d) 100mV
700V ±(1.2%+5d) 1V
Impedance : 10MΩ
Frequency response : 20V/200V range: 40-400Hz
700V range : 40-200Hz
Resistance
Range Accuracy Resolution
200Ω±(0.8%+5d) 0.1Ω
2kΩ1Ω
20kΩ10Ω
200kΩ100Ω
2MΩ
±(0.8%+3d)
1kΩ
20MΩ±(1.2%+8d) 10kΩ
Over Load protection ：250V DC/AC RMS
DC Current
Range Accuracy Resolution
20mA ±(1.2%+3d) 10uA
200mA ±(1.5%+3d) 100uA
10A ±(2.0%+5d) 10mA
Over Load protection：Fast 0.2A/250V fuse, 10A/250 fuse.
AC Current
Range Accuracy Resolution
20mA ±(1.2%+5d) 10uA
200mA ±(1.5%+5d) 100uA
10A ±(2.0%+8d) 10mA
Over Load protection：Fast 0.2A/250V fuse, 10A/250 fuse
Capacitance
Range Accuracy Resolution
20nF 10pF
200nF 100pF
20uF
±(4%+10d)
10nF
Over Load protection ：36V DC/AC RMS
Diode Test
Range Description Test Condi
t
ion
Read & display approx. forward
voltage of diode
Forward DC Current approx.
1mA. Reversed DC voltage
approx. 3V.
Buzzer sounds if resistance
Between terminals V/Ωand
COM is less than about 90Ω.
Open voltage is approx. 3V
Over load Protection: 250V DC/AC RMS
Temperature
Range Accuracy Resolution
-40℃~ 400℃±( 0.75% + 3d) 1℃
400℃~ 1000℃±( 1.5% + 15d) 1℃
Using F type thermocouple probe
2. FRONT PANEL DESCRIPTION
1. LCD display
2. DATAHOLD switch
3. FUNCTION and RANGE switch
4. INPUT terminal
3.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. If this 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 lead jacks, is for warning that the input voltage or
current should not exceed the indicated values.
This is to prevent from damaging to the internal circuits.
3.The function switch should be set to the range that you want to test before operation.
3.1 DC and AC Voltage measurement
1. Connect the BLACK test lead to “COM” jack and RED test lead the “V/Ω” jack.
2. Set the FUNCTION switch to desired DCV or ACV position and connect the probes
across the source or load under measurement.
Note:
1) If the voltage ranges is unknown beforehand set the FUNCTION switch to a high
range and work down.
2) When only the figure "1"is displayed, over range is being indicated and the
FUNCTIN switch must be set to a higher range.
3) : Do not apply more than DCV1000V/AC700Vrms to the input. Indication is
possible at higher voltages but there is danger of damaging the internal circuitry.
4) Be careful when measuring high voltage.
3.2 DC and AC Current measurement
1. Connect the BLACK test lead to “COM” jack and RED test lead to “mA” jack for
measurement up to 200mA.
2. Set the FUNCTION switch to desired current range position.
3. Connect the probes in series with the current source to be measured.
4. For current measurement from 200mA to 10A follow generally the above procedure but
connect the RED test lead to “10A” jack.
Note:
1) If the current range is unknown beforehand, set the FUNCTION switch to a high
range and work down.
2) When only the figure "1" is displayed over range is being indicated and the
FUNCTION switch must be set to a higher range.
3) : The max input current is 200mA,or 10A depending upon the jack used.
Excessive current will blow the fuse so that must be replaced.
The 10A range is not protected by a fuse.
4) The max terminal voltage drop (burden voltage) is 200mV.
3.3 Resistance measurement
1. Connect the BLACK test lead to “COM” jack and RED test lead the “V/Ω” jack.
2. Set the FUNCTION Switch to desired resistance range position.
3. Connect the probes across circuit to be tested.
Note:
1) If the resistance value being measured exceeds the max value of the range selected,
and over range indication will be displayed ("1"). Select a higher range, for resistance
of approx. 1MΩand above, the meter may take a few seconds to stabilize. This is
normal for high resistance readings.
2) When the input is not connected, i.e. at open circuit, the figure "1" will be displayed
for the over range condition.
3) When checking in-circuit resistance, be sure the circuit under test has all power
removed and that all capacitor are fully discharged.
4) Open circuit voltage is approx. 3V.
Max input overload: 250Vrms<10sec.
3.4 Capacitance measurement
1. Before connection the test capacitor, note the display which may have readings other than
zero each time the range is changed. This offset reading will not affect the accuracy for it
can be overridden by true value.
2. Connect the test capacitor to the input sockets, noting the polarity connections when
required.
Note:
1) If the capacitance value being measured exceeds the max value of the range selected,
and over range indication will be displayed ("1"). Select a higher range.
2) Before insert the capacitor into Cx socket, the LCD display may not be zero, the

residual figures will be decreased gradually and could be disregarded, because
measurement result can override this figure, without affecting the accuracy.
3) Units: 1nF=10-3uF
4) : Do not connect an external voltage or a charged capacitor (especially larger
capacitors) to the measuring terminals. Capacitors should be discharged before insert
into Cx socket.
3.5 Temperature measurement
1. Set the FUNCTION switch to the ℃range.
2. Insert the cold end (black plug) of thermocouple into socket, and put work end into
measurement place. Display reading is the temperature of measurement place in ℃.
3.6 Diode and continuity Test
1. Connect the BLACK test lead to “COM” jack and RED test lead the “V/Ω” jack..
(Note: The polarity of the red test probe is “+”).
2. Set the FUNCTION switch to “ ” position.
3. Connect the test leads across the diode under measurement, display shows the approx.
forward voltage of this diode.
4. Connect the test probes to two points of circuit, if the resistance is lower than approx. 90
Ω. Buzzer sounds.
Note:
1) When the input is not connected, i.e. at open circuit, the figure "1" will be displayed.
2) There is a milliamp current flow through the diode under test.
3) The meter displays the forward voltage drop in millivolts and overload when the diode
is reversed.
3.7 HOLD KEY ……The key is used to hold data during measurement. This function is
operative in all measurement method, Pressing the key, reading this held and “ H”
appears in the display. Pressing the key once again in order to releases the hold
function.
4. WARNING
1. When measuring voltage ensure that instrument is not connected or switched to a current
or resistance range, or to the diode check. Always ensure that the correct terminals are
used for the type of measurement to be made.
2. Pay attention when measuring voltage above 50V, especially from sources where high
energy is existed.
3. Avoid making connections to “live” circuits whenever possible.
4. When making current measurements ensure that the circuit not “live” before opening it in
order to connect the test leads.
5. Before making resistance measurements or diode test, ensure that the circuit under test is
de-energized.
6. Always ensure that the correct function and range is selected. If in doubt about the
correct range to use, start from the highest and work downwards.
7. Extreme care should be taken when using the instrument to conjunction with a current
transformer connected to the terminals if an open circuit occurs.
8. Ensure that the test leads and probes are good condition with no damage to the insulation.
9. Take care not to exceed the over-load limits as given in the specification.
10. FUSE FOR REPLACEMENT MUST BE OF THE CORRECT TYPE AND RATING.
11. Before opening the case of the instrument to replace battery or fuse, disconnect the test
leads from any external circuit, set the selector switch to “OFF” position.
5. CARE AND MAINTENANCE
5.1Care for your multi-meter
Your Digital Multi-meter is an example of superior design and craftsmanship. The
following suggestions will help you care for the multi-meter so you can enjoy it for
years.
1. Keep the multimember dry. If it gets wet, wipe it dry immediately. Liquids can contain
minerals that can corrode electronic circuits.
2. Use and store the multi-meter only in normal temperature environments. Temperature
extremes can shorten the life of electronic devices, damage batteries, and distort or melt
plastic part.
3. Handle the multi-meter gently and carefully. Dropping it can damage the circuit boards
and case and can cause the multi-meter to work improperly although the holster can
provide enough protection.
4. Keep the multi-meter away from dust and dirt, which can cause premature wear of parts.
5. Wipe the multi-meter with a damp cloth occasionally to keep it looking new. Do not use
harsh chemicals, cleaning solvents, or strong detergents to clean the multi-meter.
6. Use only fresh battery of the required size and type. Always remove old or weak
batteries.
They can Leak chemicals that destroy electronic circuits.
5.2 Maintenance
1) 9-Volt battery replacement
a. Ensure the instrument is not connected to any external circuit. Set the selector switch to
OFF position and remove the test leads from terminals.
b. Remove the screw on the bottom case and lift the bottom case.
c. Remove the spent battery and replace it with a battery of the same type.
2) Fuse replacement
a. Ensure the instrument is not connected to any external circuit. Set the selector switch to
OFF position and remove the test leads from terminals.
b. Remove the screw on the bottom case and lift the bottom case.
c. Replace the fuse with same type and rating: 5x20mm, 200mA/250V, 10A/250V
fast-blow fuse or as the replacements.