USER'S MANUAL
Multimeter
True RMS Auto ranging
DMR-6550
CIRCUIT-TEST ELECTRONICS
www.circuittest.com
Introduction
This meter measures AC/DC Voltage, AC/DC Current, Resistance,
Capacitance, Frequency, Diode Test, Continuity plus Thermocouple
Temperature. Proper use and care of this meter will provide many years of reliable service.
Safety
This symbol adjacent to another symbol, terminal or operating device indicates that the operator must refer to an explanation in the Operating Instructions to avoid personal injury or damage to the meter.
This WARNING symbol indicates a potentially hazardous situation, which if not avoided, could result in death or serious injury.
This CAUTION symbol indicates a potentially hazardous situation, which if not avoided, may result damage to the product.
This symbol advises the user that the terminal(s) so marked must not be connected to a circuit point at which the voltage with respect to earth ground exceeds (in this case) 500 VAC or VDC.
This symbol adjacent to one or more terminals identifies them as being associated with ranges that may, be subjected to particularly hazardous voltages. For maximum safety, the meter and test leads should not be handled when these terminals are energized.
Double Insulation.
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SAFETY INFORMATION
Caution and proper guidelines must be followed for personal and product safety.
Read this instruction manual carefully and completely before using the meter.
Lack of caution or poor safety practices can result in serious injury or death.
• Always start with power off. Set the function switch to the correct setting before making any measurements and do not change position of the function switch during measurements.
• Do not use the meter if the meter or test leads look damaged or if there is doubt that the meter is not operating properly.
• When using the test probes always keep fingers behind the finger guards.
Never touch the exposed probe tip.
• Always consider circuits to be energized. Never assume any equipment to be de-energized.
• Use caution when working above 35VDC or 25VAC RMS as these voltages pose a shock hazard.
• Never connect unit to AC or DC powered circuits when the function switch is set to resistance, diode check or continuity ranges.
• Always disconnect the power when performing resistance, or diode tests.
• Always turn off the power to the circuit under test before unsoldering or breaking the circuits. Small amount of current can be dangerous.
• Disconnect test leads before removing the batteries or the fuse.
• Do not operate the unit unless the case is completely closed.
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SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be operated with caution.
The rules listed below must be carefully followed for safe operation.
1. NEVER apply voltage or current to the meter that exceeds the specified maximum:
Function
V DC or V AC
A DC/AC
Frequency, Resistance,
Capacitance, Duty Cycle, Diode test, Continuity
Temperature
Input Limits
Maximum Input
1000VDC/VAC
10A DC/AC (30 seconds max every
15 minutes)
600V DC/AC rms
600V DC/AC rms
2. USE EXTREME CAUTION when working with high voltages.
3. NEVER connect the meter leads across a voltage source while the function switch is in the current, resistance, or diode mode. Doing so can damage the meter.
4. ALWAYS discharge filter capacitors in power supplies and disconnect the power when making resistance or diode tests.
5. ALWAYS turn off the power and disconnect the test leads before opening the covers to replace the fuse or batteries.
6. NEVER operate the meter unless the back cover and the battery and fuse covers are in place and fastened securely.
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Controls and Jacks
1. 6000 count LCD Display
2. Function switch
3. 10A (positive) input jack
4. COM (negative) input jack
5. Positive input jack
6. HOLD & Backlight button
7. Max/Min button
8. Range/ /Diode button
9. Hz/% button
Symbols and Annunciators
Continuity
Low Battery
Diode
HOLD
Data Hold
AUTO
AutoRanging
AC
Alternating Current or Voltage
DC
Direct Current or Voltage
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Specifications
Display:
Polarity:
Input Impedance:
6000 counts LCD display.
Automatic, (-) negative polarity indication.
7.8MΩ
Overrange:
AC Response:
“OL” mark indication.
True RMS
Low battery indication: “ ” is displayed if the battery voltage drops below operating voltage.
Measurement rate:
Auto power off:
2 times per second, nominal.
Automatically shuts down after approx. 15 minutes of inactivity.
Operating Temperature: 0ºC to 50ºC (32ºF to 122ºF) at < 70 % relative humidity.
Storage temperature:
-20ºC to 60ºC (-4ºF to 140ºF) at < 80 % relative humidity.
Fuse:
Battery:
10A/250V Fuse, Fast blow 5x20mm
One 9V, NEDA 1604 battery.
Dimensions:
Weight:
Enclosure:
Safety / Approvals:
150 (H) x 70 (W) x 48 (D) mm
Approx.: 255g
Double molded
This meter is UL and CUL approved and conforms to IEC61010-1 for Overvoltage Category
CAT III 600V and CAT II 1000V.
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DC Voltage
Range
600.0mV
6.000V
60.00V
600.0V
1000V
AC Voltage
Range
6.000V
60.00V
600.0V
1000V
Resolution
0.1mV
1mV
10mV
100mV
1V
Resolution
1mV
10mV
100mV
1V
Accuracy
±0.5% of reading ± 2 digits
±1.2% of reading ± 2 digits
±1.5% of reading ± 2 digits
Accuracy
±1.5% of reading ± 10 digits
±1.5% of reading ± 10 digits
±2.0% of reading ± 10 digits
DC Current
Range
6A
10A
Resolution
1mA
10mA
Accuracy
±2.5% of reading ± 5 digits
AC Current
Range
6A
10A
Resolution
1mA
10mA
Accuracy
±3.0% of reading ± 5 digits
Overload Protection: 10A / 250V Fuse.
Note: Accuracy is given at 18ºC to 28ºC (65ºF to 83ºF), < 70 % RH
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Resistance
Range
600.0Ω
6.000kΩ
60.00kΩ
600.0kΩ
6.000MΩ
60.00MΩ
Resolution
0.1Ω
1Ω
10Ω
100Ω
1kΩ
10kΩ
Capacitance (Auto-ranging)
Range
40.00nF
400.0nF
4.000uF
40.00uF
400.0uF
4000uF
Resolution
10pF
0.1nF
1nF
10nF
0.1uF
1uF
Frequency (Auto-ranging)
Range
9.999Hz
99.99Hz
999.9Hz
9.999kHz
99.99kHz
999.9kHz
10MHz
Resolution
0.001Hz
0.01Hz
0.1Hz
1Hz
10Hz
100Hz
1kHz
Sensitivity: >0.5V RMS while ≤1MHz;
Sensitivity: >3V RMS while >1MHz
Accuracy
±1.2% of reading ± 4 digits
±1.0% of reading ± 2 digits
±1.2% of reading ± 2 digits
±2.0% of reading ± 2 digits
±5.0% of reading ± 10 digits
Accuracy
±5.0% of reading ± 50 digits
±3.0% of reading ± 5 digits
±3.0% of reading ± 5 digits
±5.0% of reading ± 5 digits
±5.0% of reading ± 5 digits
Accuracy
±1.5% of reading ± 5 digits
±1.2% of reading ± 3 digits
±1.5% of reading ± 4 digits
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Duty Cycle
Range
0.1%~99.9%
Resolution
0.1%
Pulse width: >100us, <100ms;
Frequency width: 5Hz – 150 kHz
Sensitivity: >0.5V RMS
Temperature
Range
-20ºC~+760ºC
-4ºF~+1400 ºF
Resolution
1ºC
1ºF
Sensor: Type K Thermocouple
Accuracy
±1.2% of reading ± 2 digits
Accuracy
±3% of reading ±5ºC/9ºF
Diode Test
Range
0.3mA typical
Resolution
1 mV
Open circuit voltage: 1.5V dc typical
Accuracy
±10% of reading ± 5 digits
Audible continuity
Audible threshold: Less than 100Ω Test current: <0.3mA
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Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are very dangerous and should be measured with great care.
1. ALWAYS turn the function switch to the OFF position when the meter is not in use. This meter automatically shuts OFF after 15 minutes of inactivity.
2. If “OL” appears in the display during a measurement, the value exceeds the range you have selected. Change to a higher range.
NOTE: On some low AC and DC voltage ranges, with the test leads not connected to a device, the display may show a random, changing reading. This is normal and is caused by the high-input sensitivity. The reading will stabilize and give a proper measurement when connected to a circuit.
Autoranging/Manual Range Selection
When the meter is first turned on, it automatically goes into Autoranging. This automatically selects the best range for the measurements being made and is generally the best mode for most measurements. For measurement situations requiring that a range be manually selected, perform the following:
1. Press the RANGE key. The “AUTO” display indicator will turn off.
2. Press the RANGE key to step through the available ranges until you select the range you want.
3. To exit Manual Ranging, press and hold RANGE key for 2 seconds.
NOTE: Manual ranging does not apply for Capacitance, Frequency functions.
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MAX/MIN
NOTE: When using the MAX/MIN function in Autoranging mode, the meter will
“lock” into the range that is displayed on the LCD when MAX/MIN is activated.
If a MAX/MIN reading exceeds that range, an “OL” will be displayed. Select the desired range BEFORE entering MAX/MIN mode.
1. Press the MAX/MIN key to activate the MAX/MIN recording mode. The display icon "MAX" will appear. The meter will display and hold the maximum reading and will update only when a new “max” occurs.
2. Press the MAX/MIN key again and the display icon "MIN" will appear.
The meter will display and hold the minimum reading and will update only when a new “min” occurs.
3. To exit MAX/MIN mode press and hold the MAX/MIN key for 2 seconds
Display Backlight
Press and hold the HOLD key for >1 second to turn on or off the display backlight function. The backlight will automatically turn off after 10 seconds.
HOLD
The hold function freezes the reading in the display. Press the HOLD key momentarily to activate or to exit the HOLD function.
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DC Voltage Measurements
CAUTION: Do not measure DC voltages if a motor on the circuit is being switched ON or OFF. Large voltage surges may occur that can damage the meter.
1. Set the function switch to the position.
2. Insert the black test lead banana plug into the negative COM jack and the red test lead banana plug into the positive V jack.
3. Touch the test probe tips to the circuit under test. Be sure to observe the correct polarity (red lead to positive, black lead to negative).
4. Read the voltage in the display.
AC Voltage Measurements
WARNING: Risk of Electrocution. The probe tips may not be long enough to contact the live parts inside some 240V outlets for appliances because the contacts are recessed deep in the outlets. As a result, the reading may show 0 volts when the outlet actually has voltage on it. Make sure the probe tips are touching the metal contacts inside the outlet before assuming that no voltage is present.
CAUTION: Do not measure AC voltages if a motor on the circuit is being switched ON or OFF. Large voltage surges may occur that can damage the meter.
1. Set the function switch to the position.
2. Insert the black test lead banana plug into the negative COM jack and the red test lead banana plug into the positive V jack.
3. Touch the test probe tips to the circuit under test.
4. Read the voltage in the display.
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DC Current Measurements
CAUTION: Do not make current measurements on the 10A scale for longer than 30 seconds. Exceeding 30 seconds may cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM jack.
2. For DC current measurements, set the function switch to the position and insert the red test lead banana plug into the 10A jack.
3. Remove power from the circuit under test, then open up the circuit at the point where you wish to measure current.
4. Touch the black test probe tip to the negative side of the circuit. Touch the red test probe tip to the positive side of the circuit.
5. Apply power to the circuit and read the current in the display.
AC Current Measurements
WARNING: To avoid electric shock, do not measure AC current on any circuit whose voltage exceeds 250V AC.
CAUTION: Do not make current measurements on the 10A scale for longer than 30 seconds. Exceeding 30 seconds may cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM jack.
2. For AC current measurements, set the function switch to position and insert the red test lead banana plug into the 10A jack.
3. Remove power from the circuit under test, then open up the circuit at the point where you wish to measure current.
4. Touch the black test probe tip to the negative side of the circuit. And touch the red test probe tip to the positive side of the circuit.
5. Apply power to the circuit.
6. Read the current in the display. The display will indicate the proper decimal point, value and symbol.
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Resistance Measurements
WARNING: To avoid electric shock, disconnect power to the unit under test and discharge all capacitors before taking any resistance measurements.
Remove the batteries and unplug the line cords.
1. Set the function switch to the Ω position.
2. Insert the black test lead banana plug into the negative COM jack and the red test lead banana plug into the positive Ω jack.
3. Touch the test probe tips across the circuit or part under test. It is best to disconnect one side of the part under test so the rest of the circuit will not interfere with the resistance reading.
4. Read the resistance in the display. The display will indicate the proper decimal point, value and symbol.
Continuity Check
WARNING: To avoid electric shock, never measure continuity on circuits or wires that have voltage on them.
1. Set the function switch to the position.
2. Insert the black lead banana plug into the negative (-) jack COM and the red test lead banana plug into the positive (+) jack Ω.
3. Press the RANGE/ / button until symbol appears in the display.
4. Touch the test probe tips to the circuit or wire you wish to check.
5. If the resistance is less than approximately 100Ω, the audible signal will sound. The display will also show the actual resistance.
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Diode Test
WARNING: To avoid electric shock, do not test any diode that has voltage on it.
1. Set the function switch to position.
2. Press the RANGE/ / button until the symbol appears in the display.
3. Insert the black test lead banana plug into the negative (-) jack COM and the red test lead banana plug into the positive (+) jack Ω.
4. Touch the test probe tips to the diode or semiconductor junction you wish to test. Note the meter reading
5. Reverse the probe polarity by switching probe position. Note this reading.
6. The diode or junction can be evaluated as follows:
A. If one reading shows a value and the other reading shows OL, the diode is good.
B. If both readings show OL, the device is open.
C. If both readings are very small or 0, the device is shorted.
NOTE: The value indicated in the display during the diode check is the forward voltage.
Frequency/Duty Cycle Measurements
1. Set the rotary function switch to the “Hz %” position.
2. Insert the black lead banana plug into the negative COM jack and the red test lead banana plug into the positive Hz jack.
3. Touch the test probe tips to the circuit under test.
4. Read the frequency on the display.
5. Press the Hz/% button again to indicate “%” on the display.
6. Read the % of duty cycle on the display.
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Capacitance Measurements
WARNING: To avoid electric shock, disconnect power to the unit under test and discharge all capacitors before taking any capacitance measurements.
Remove the batteries and unplug the line cords.
1. Set the function switch to the position.
2. Insert the black test lead banana plug into the negative (-) jack COM and the red test lead banana plug into the positive (+) jack .
3. Touch the test leads to the capacitor to be tested.
Temperature Measurements
WARNING: To avoid electric shock, disconnect both test probes from any source of voltage before making a temperature measurement.
1. Set the function switch to ºF, or ºC position.
2. Insert the type K thermocouple probe black test lead banana plug into the negative COM jack and the red test lead banana plug into the positive ºF / ºC jack.
3. Touch the Temperature Probe head to the part whose temperature you wish to measure. Keep the probes touching the part under test until the reading stabilizes (about 30 seconds).
4. Read the temperature in the display.
WARNING: To avoid electric shock, be sure the thermocouple has been removed before changing to another measurement function
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Maintenance
Replacing the Battery
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before removing the battery door.
1. will appear in the display when the battery drops below the operating voltage and requires replacing.
2. Turn off the meter and disconnect the test leads from the meter.
3. Remove the two screws securing the battery cover.
4. Replace the 9V battery observing the correct polarity.
5. Replace the cover and secure the two screws.
WARNING: To avoid electric shock, do not operate your meter until the battery door is in place and fastened securely.
Replacing the Fuses
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before removing the fuse cover.
1. Turn off the meter and disconnect both test leads from the meter.
2. Remove the two screws securing the battery/fuse cover and remove the battery.
3. Remove the old fuse from its holder by gently pulling it out.
4. Replace with fuse of proper size and value (10A/250V fast blow only).
5. Replace the battery and the cover and tighten the screws.
WARNING: To avoid electric shock, do not operate your meter until the fuse door is in place and fastened securely.
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Limited Warranty
Circuit-Test Electronics warrants to the original purchaser that this product be free of defect in material or workmanship for a period of 2 years from the date of purchase.
Any product which has been subjected to misuse or accidental damage is excluded from the warranty. Except as stated above, Circuit-Test Electronics makes no promises or warranties either expressed or implied including warranties of merchantability or the fitness for any particular purpose.
M-DMR-6550 / 07R13
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