Handheld Digital Multimeter GDM-350B USER MANUAL GW INSTEK PART NO.
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Table of Contents Table of Contents OVERVIEW............................................................................................................................. 2 Unpacking & Inspection ................................................................................................................... 3 Safety Information............................................................................................................................. 4 International Electrical Symbols ...................
GDM-350B User Manual OVERVIEW The GDM-350B multimeter is a hand-held 3 1/2digit multimeter with an advanced design, multiple functions and reliable performance. This meter is fully capable of measuring both AC and DC voltage, DC current, resistance, temperature, the forward voltage drop of diodes, transistors, hFE and continuity tests. The multipurpose socket is used to measure SMTs as well. This operating manual covers information on safety and precautions to fulfill CE standards.
OVERVIEW Unpacking & Inspection Open the package case and take out the Meter. Check the following items carefully to see if any parts are missing or damaged: Item 1 2 3 4 Description Operating Manual Test Leads K-type Temperature Probe (Nichrome-Nickel Aluminum Thermocouple) Multi-Purpose Socket Qty 1 piece 1 pair 1 piece 1 piece In the event that you find any parts missing or damaged, please contact your dealer immediately.
GDM-350B User Manual Safety Information This meter complies with the IEC/EN61010-1 standard, pollution degree 2, overvoltage category (CAT III 250V) with double insulation. Only use the meter as specified in this operating manual, otherwise the protection provided by the meter may be impaired. 1. Before using the meter inspect the case. Do not use the meter if it is damaged or if the case (or part of the case) is removed. Look for cracks or missing plastic.
OVERVIEW 7. When each measurement has been completed, disconnect the test leads from the DUT and then turn the power off from the meter. Remove the test leads from the input terminals of the meter. This is vital for high current measurement. 8. When the meter is working at an effective voltage over 60V in DC or 30Vrms in AC, special care should be taken. 9. Do not use or store the meter in an environment with high temperature and humidity. The performance of the meter may deteriorate if dampened. 10.
GDM-350B User Manual International Electrical Symbols Battery has insufficient charge Ground Warning: Refer to the Operating Manual AC (Alternating Current) DC (Direct Current) Double Insulated Conforms to Standard of European Union 6
OVERVIEW Overall Specification 1. Maximum voltage between any terminal and ground: Refer to the different input protection voltage ranges shown on the terminals. 2. 10A terminal: Set (CE) 10A H 240V Fast Type Ceramic Fuse φ6x25mm. 3. mA terminal: Set (CE) 1 A H 240V Fast Type Ceramic Fuse φ6x25mm. 4. Operating temperature: 0˚C~40˚C, 32˚F ~104˚F. Relative Humidity: 0˚C ~30˚C below ≤75%, 30˚C ~40˚C below ≤50%. Storing temperature:-10˚C ~50˚C (14˚F ~122˚F). 5.
GDM-350B User Manual The Meter Structure (see diagram 1) 1. 2. 3. 4. 5.
MEASUREMENT OPERATION MEASUREMENT OPERATION First check to see that the 9V battery is charged. Turn the rotary switch to a measurement position. If the battery charge is low, the “ ” indicator will be displayed on LCD panel. Ensure the input voltage or current does not exceed 250Vrms and 10A, respectively.
GDM-350B User Manual DC or AC Voltage Measurement 1. 2. 3. 10 (see diagram 2) Diagram 2 Turn the rotary switch to the V or V position for voltage measurement. Insert the red test lead into the “V” terminal and the black test lead into the “COM” terminal, Connect the test leads to the DUT being measured. The measured value shows the true root mean square voltage (for stable inputs). For each range, the meter has an input impedance of 10MΩ. Input impedance for V is about 4.5MΩ.
MEASUREMENT OPERATION high impedance circuits. If the circuit impedance is less than or equal to 10kΩ, the error is negligible (0.1% or less). Warning: To avoid damage to the meter, please do not attempt to input more than 250V. To avoid electrical shock, please pay attention during high voltage measurement.
GDM-350B User Manual DC Current Measurement 1. 2. 12 (see diagram 3) Diagram 3 Turn the rotary switch to the “A “ position for current measurement. Insert the red test lead into the “mA” or “10A” terminal, and the black test lead into the “COM” terminal. Connect the test leads to the DUT being measured. The measured value shows on the display.
MEASUREMENT OPERATION Warning: Pre-requisites: Remove the power from the circuit before connecting the test leads to the DUT. Select the correct terminal input and turn the rotary switch to select the measurement function. If the correct range is not known, select the highest range and work your way down to a lower range if needed. Fuses are located on the mA and 10A current input terminals. Never attempt connecting the test leads to any circuits that are connected to mains power.
GDM-350B User Manual Resistance Measurement 1. 2. 14 (see diagram 4) Diagram 4 Turn the rotary switch to the “Ω” position for resistance measurement. Insert the red test lead into the “Ω” terminal and the black test lead into the “COM” terminal. Connect the test leads to the DUT being measured. The measured value shows on the display.
MEASUREMENT OPERATION Warning: If the LCD displays “1”, it indicates the circuit is open or that the resistance exceeds the maximum range of the meter. To maintain the resistance measurement accuracy, remove circuit power and discharge all high voltage capacitors when measuring resistance. The test leads cause a resistance drop of 0.1Ω ~0.2Ω. In order to obtain precise readings for low-resistance measurements, the resistance of the test leads must be deducted from the measured resistance.
GDM-350B User Manual Diode Measurement 1. 2. 3. 16 (see diagram 5) Diagram 5 Turn the rotary switch to the “ ” position for diode measurement. Insert the red test lead into the “ ” terminal and the black test lead into the “COM” terminal. The red test lead is “+”, the black test lead is “-”. In a circuit, a good diode should still produce a forward voltage drop reading of 500~800mV. However, a reverse voltage drop reading can vary depending on the resistance of other pathways between the probe tips.
MEASUREMENT OPERATION Warning: The LCD displays “1” to indicate that the circuit is open or that the polarity of the diode is incorrect. To ensure the accuracy of the diode measurement, disconnect power from the circuit and discharge all high voltage capacitors during the measurement. The open circuit voltage for diodes is 2.3V. Do not input greater than DC 60V and AC 30V to prevent damage and injury.
GDM-350B User Manual Continuity Measurement Diagram 6 18 (see diagram 6)
MEASUREMENT OPERATION 1. Turn the rotary switch to the “ ” position. 2. Insert the red test lead into the “ΩmA ” terminal and the black test lead into the “COM” terminal. If the resistance between both terminals is >70Ω, it indicates an open-circuit and no buzzer will sound, but if the resistance between both terminals is ≤10Ω, it indicates a good connection and the buzzer will sound. The resistance measurement is displayed on the LCD (Unit: Ω).
GDM-350B User Manual Transistor hFE measurement Diagram 7 20 (see diagram 7)
MEASUREMENT OPERATION 1. 2. 3. 4. Turn the rotary switch to the “hFE” position. Put the multi-purpose socket into the terminal. Check whether the transistor is either PNP or NPN or SMT, then connect the transistor to be measured to the corresponding jacks. The LCD display shows the hFE reference value. The testing requirement: basic current 10µA,Vce of 2.3V. Warning: To avoid damage to the Meter or to the DUT, do not input any voltage over 60V DC or 30V AC.
GDM-350B User Manual Temperature Measurement Diagram 8 22 (see diagram 8)
MEASUREMENT OPERATION 1. 2. 3. 4. Turn the rotary switch to the “˚C” position. Put the multi-purpose socket into the correct terminal. The K-type thermocouple can only be used for measurements below 230˚C, if you want to measure over 230˚C, you need to buy another type of thermocouple. When the LCD displays “1”, it indicates that the K-type thermocouple is not connected. When the ˚C terminal and the COM terminal are shorted, the meter will show the room temperature.
GDM-350B User Manual ACCURACY SPECIFICATIONS Accuracy: ±(a% reading + b digits), guaranteed for 1 year Operating temperature: 23˚C ± 5˚C Relative Humidity: <75% DC Voltage Range Resolution Accuracy 200mV 0.1mV 2000mV 1mV ±(0.5% Reading + 2 Digits) 20V 0.01V 200V 0.1V 250V 1V ±(0.8% Reading + 2 Digits) Input impedance: all range 10MΩ. Maximum input voltage: 250V DC.
ACCURACY SPECIFICATIONS AC Voltage Range Resolution Accuracy 200V 0.1V ±(1.2 Reading% +3 Digits) 250V 1V Input impedance: about 4.5MΩ; Frequency: 45Hz~400Hz. Display: effective value of a sine wave (average value) each measurement is applicable from 5% of range as reference. Maximum input voltage: 250V AC.
GDM-350B User Manual DC Current Range Resolution Accuracy 2000µA 1µA ±(1% Reading +2 Digits) 20mA 0.01mA ±(1% Reading + 2 Digits) 200mA 0.1mA ±(1.2% Reading +2 Digits) 10A 0.01A ±(2% Reading +5 Digits) Overload Protection: mA range: F2 fuseφ6×25mm, F 1A H 240V (CE) 10A range: F1 fuseφ6×25mm, F 10A H 240V (CE) Warning: When ≤ 5A Continuous measurement is allowed. When > 5A Measurements must not take longer than 10 seconds with a wait of 15 minutes between measurements.
ACCURACY SPECIFICATIONS Resistance Range Resolution Accuracy 200Ω 0.1Ω 2000Ω 1Ω 20kΩ 0.01kΩ ±(0.8% Reading + 5 Digits) 200kΩ 0.1kΩ 2000kΩ 1kΩ 20MΩ 0.
GDM-350B User Manual Temperature Measurement Range Resolution Accuracy -40˚C~ -20˚C -(8% Reading + 5 digits) -20˚C~0˚C ± 4 digits 1˚C > 0˚C~100˚C ±(1.0% Reading + 3 digits) >100˚C~1000˚C ±(2.5% Reading + 2 digits) Overload Protection: 250V DC or AC The enclosed K-type thermocouple can only be used for temperature measurements less than 230˚C.
ACCURACY SPECIFICATIONS Diode, Transistor Function Diode Transistor Range hFE Resolution 1mV 1 Remark Display positive voltage decline Continuity Test Function Range Resolution Continuity Test 1Ω Overload Protection: 250V DC or AC.
GDM-350B User Manual MAINTENANCE Warning Make sure the test leads are removed and the power is turned off the meter before opening the cover. General Service and Maintenance Periodically wipe the case with a damp cloth and mild detergent. Do not use abrasives or solvents. If there are any abnormalities in the meter, stop using the meter and return to an authorized service center. When the meter needs to be calibrated, return the unit to an authorized service center.
MAINTENANCE Replacing the Battery and Fuse (see diagram 12) Warning On the LCD display, the battery warning indicator, “ ” indicates the battery is low and needs to be replaced with a new battery. Failure to replace the battery causes the measured result to be unstable.
GDM-350B User Manual Operating Steps: 1. Turn the power off and remove the test leads from the meter. 2. Use a screwdriver to remove the screws from the battery cover. The old battery can now be removed. 3. The fuses can be replaced by using a screwdriver to remove the two screws holding the fuses in place. Only replace fuses with the same type and specifications.
