MAXWELL 25304 Digital Multimeter User Manual

MAXWELL 25304 Digital Multimeter User Manual

General description

°C, relative humidity:

< 80%

Storage environment| temperature: -20…60°C, relative humidity:

< 80%

Battery| 1 x 9V IEC 6F22 Battery
Dimensions| 190 mm x 88,5 mm

x 27,5 mm

Weight| 422 g (with battery)
Accessories| Instructions, connection cable (red and black, 1 pair), hitting pocket protector, K-type thermometer probe

Electrical Characteristics

DCV

250 VDC or AC peak value

ACV

(sine wave and triangular wave)

****| 40 Hz – 200 Hz

(other waves)

DCA

200 mA / 250 V fuse with “F” mark

ACA

200 mA / 250 V fuse with “F” mark
Frequency response| 40 Hz – 1 KHz

(sine wave and triangular wave)

---|---
40 Hz – 200 Hz

(other waves)

Capacitance

Transistor hFE-Test

(0-1000)

(NPN or PNP)

| Base current appr. 10 μA VCE appr.

3 V

Resistance

The reading be displayed slowly when the measurement is more than 1 MΩ. Please wait it to be stable.

Temperature (with a K type temperature sensor)

Diode and Continuity Testing

voltage is approx. 3 V
Buzzer makes a long sound while resistance is less than

70 Ω +/- 20 Ω

| Opening voltage appr. 3 V
Overload protection| 250 V DC or AC peak value
---|---

Frequency

Inductance

Warning: Do not connect external voltage source to the connectors!

Product Description

1. LCD: display the measuring value and unit
2. Function keys
3. Power switch: turn on/off the power
4. Data hold and backlight / work light button: Press briefly to keep the currently measured value on the display, while “HOLD” is displayed.
5. Transistor test socket.
6. Press “REL/MAX/MIN”, then you can test the relative magnitude. If you hold the “REL/MAX/MIN” for more than 2s, you can test the Max and Min value.
7. Range knob: to select measuring function and range.
8. Voltage, resistance, frequency, capacitance, diode port – „V / Ω”
9. Common measuring port (COM)
10. Port for measuring current less than 200 mA and inductivity
11. Port for measuring current 20 A

Usage

• Check the 9 V battery and press the “POWER” button. If the battery is depleted, the battery symbol appears on the screen.
• The signs near the connectors warn about not exceeding the inward voltage or current. This is to prevent damage to the inside circuits.
• Before measuring set the function switch to the desired position.
• If you are unsure about the magnitude of the result, set the switch to the highest possible range and go backwards until you reach the correct setting.

DC and AC voltage measuring

• Connect the black measuring wire to the „COM”, and the red one to the „V / Ω” connector.
• Set the function switch to the correct “V” position and connect the wires to the voltage source paralelly.

Note:

• If you are unsure about the magnitude of the result, set the switch to the highest possible range and go backwards until you reach the correct setting.

• Set the DC / AC switch to the desired (DC or AC) function.

• If only an „OL” is displayed on the screen, it signals overload.
  Switch to a higher range.

• Do not connect voltage exceeding DC 1000 V / AC 700 V to the connectors. Results may be displayed at higher voltages also, but this may lead to damage to the inside circuits.

• Do not touch the high voltage circuits while measuring.

DC and AC current measuring

• Connect the black wire to the „COM” and the red one to the „mA” connector (max. 200 mA) or the „20A” connector for measuring 200 mA or 20 A.
• Set the function switch to the proper range.
• Connect the the wires to the circuit serially.
• For measuring current between 200 mA and 20
  A follow the instructions above, but connect the red wire to the „20A” connector.

Note:

• If you are unsure about the magnitude of the result, set the switch to the highest possible range and go backwards until you reach the correct setting.

• If only an „OL” is displayed on the screen, it signals overload. Switch to a higher range.

• The maximum inward current is 200 mA or 20 A depending on the connector. (For maximum 15 seconds.)
  Too much currency overheats the fuse which needs to be replaced. The 20 A measuring range is not protected.

• Maximum overload voltage: 200 mV.

Resistance measuring

• Connect the black wire to the „COM”, and the red one to the „V / Ω” connector.

• Set the function switch to the desired resistance range.

• Touch the wires to the measured circuit paralelly.
  Warning: make sure that the measured circuit is not under power!

• The maximum overload capability for the connector is 250 V RMS (for maximum 10 seconds).

Note:

• If the measured resistance value is over the maximum threshold and the device signals overload („OL”), select a higher range. When measuring above 1 MW it may take a few seconds for the device to stabilize the displayed value.
  This is completely normal for such resistors.

• If you do not connect a resistor to the connector (or there is a break) the display will show „OL”.

• If you are measuring a resistor that is part of a circuit make sure that the circuit is not under power and all capacitors are discharged.

• Do not connect inward voltage to the device as it may lead to damage to the inside circuits.

• The outward voltage on connectors not under power is approximately 3 V.

Capacity measuring

• Set the function switch to “2 mF” position.
• Connect the measured capacitor to the „V / Ω” and “COM” connector. Pay attention to the correct polarity.

Note:

• If the measured value exceeds the maximum value of the selected range and the device signals overload („OL”).
• Unit: 1 nF=10-3 μF or 1000 pF
• Do not connect external voltage or current to the connector! Turn off the power and discharge the capacitors before measuring. Also discharge the electrolyte capacitors before measuring!
• Before measuring discharge the electrolyte capacitors more times.

Diode and continuity test

• Connect the black measuring wire to the „COM”, the red one to „V / Ω” connector. (Note: the polarity of the red wire is: +)

• Set the function to „ ” position.

• Touch the wires to the diode’s connectors.
  The screen shows the opening voltage of the diode.

• Connect the wires to two points of the circuit. If the resistance is below 90 Ω the device beeps.

Note:

• If you do not connect a unit to the connectors (or there is a  break) the display will show „OL”.
• During the test 1 mA current goes through the diode.
• The display shows the opening voltage of the diode in mV, and overload if the diode is connected with the polarity reversed

Temperature measuring

• Set the function switch to “°C/°F” position.
• Connect the black wire of the temperature measuring sensor to the „COM” connector and the red one to the „V/Ω” connector. Put the sensor to the place measured. The display shows the measured value in °C or °F (press “HOLD” button to select).

Note:

• The device functions with a special temperature measuring sensor.
• If the sensor is not connected to the connector, the device displays the temperature of the environment.
• Do not connect outward voltages to the connectors, if the device is in temperature measuring function.

Transistor hFE test

• Set the function switch to “hFE” position.
• Determine if the transistor is NPN or PNP and place it in the proper connector.
• The amplification factor of the transistor is displayed on the screen.
• IB = 10 μA, VCE = 2,8 V

Frequency measuring

• Connect the measuring wire or the shielded cable to the „COM” and „V / Ω” connectors.
• Set the function switch to „20 MHz” position and touch the wires to the signal source.

Note:

• Do not measure frequency at a voltage exceeding 250 V(RMS).
• In noisy environment it is advised to use a shielded cable for measuring small values.
• Avoid touching the circuit when measuring high voltage!
• Frequency measuring changes range automatically.

Inductance measuring

• Set the functions with to the desired measuring range.
• Connect the measured inductor to the “mA” and “COM” terminal. Remark:
• If the measured inductance is not known, start measuring at H range until overload signal turns off.
• Inductors with low inductance function as short circuits. If possible, do not connect such inductors to the connectors.

Auto Power Off

• After stop working for 15 minutes, the meter will be into sleep mode. Press “POWER” key can back to work.
• Press “REL/MAX/MIN” key and at the same time with the “POWER” key the “APO” symbol will disappear, now you already closed the function of auto power off.

Warning

• When measuring voltage make sure that the wires are not connected to a current measuring connector and that the function switch is not in resistance or diode measuring measuring mode. Always check if you have connected the wires into the proper connectors.
• Be careful when measuring voltage above 50 V, especially with high voltage equipment.
• Avoid connecting to „live” circuits.
• Turn off the power in the circuit before connecting the multimeter to measure current and do not measure above 20 A.
• Before measuring resistance and diode make sure the circuit is not under power.
• Always set the function and measuring range appropriate for the measuring. If in doubt, set the maximum measuring range and go backwards.
• Make sure that the wire and its isolation is not damaged.
• Only replace fuses to the same type and value.
• When replacing the fuse or battery make sure all external power sources are turned off and that the multimeter is turned off as well.

Care and Maintenance

Operation

• Keep the multimeter dry. If it gets wet, dry it up immediately. The liquid corrodes the electric circuit.
• The multimeter should be stored and used only at normal temperature. High temperature can shorten the lifetime of electronic devices, damage to the batteries and distort, melt the plastic parts.
• Handle the multimeter carefully. If it is dropped that can cause damage to the electric circuit and to the case which leads to the improper operation of the multimeter.
• Keep away the multimeter from dust and dirt which results in premature wear of the components.
• The multimeter can be cleaned with wet cloth. Do not use chemicals, solvents or strong detergents for cleaning.
• Servicing
• Battery replacement (1 piece 9V)
• Turn off all external circuits. Switch off the multimeter and pull out the test lead of the socket.
• Unscrew the screws and remove the bottom cover.
• Remove the low battery and replace a same type of it.

Fuse replacement

• Turn off all external circuits. Set the switch to OFF position and pull out the test lead of the socket.
• Unscrew the screws and remove the bottom cover.
• Replace the blown out fuse to a same type and valued (5×20 mm, 200 mA / 250 V „F” signed.)

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