HP-37B
DIGITAL MULTIMETER
OPERATOR’S MANUAL
1. Overview
The multimeter is characterized at slim size, portable, stable performance and
anti-droppingcapacity.Using31/2digits LCD monitor with character 28mm
high, theyoffer clear readings. With overall circuitrydesigncenteringon
large-scale ICA/D converters in conjunction and over-load protection circuit,
the metersgive excellent performance and exquisite makingas a handyutilit
y
instrument.
The meters can be used to measure DC &ACvoltage, DC &ACcurrent,
resistance, capacitor, temperature, batterytest, Non ContactACVoltage(NCV
)
detection, positive diode voltage fall and audible continuity.
2. Panel Layout
1
Test lead fixture: Fix the test lead.
2
CDS sensor: The CDS sensor can reaction to the ambient brightness
range, then automaticallycontrol the LCD backlight to lighten orgoout.
3
NCV detection area: Non ContactACVoltage(NCV)detection area.
4
NCV red light: Non ContactACVoltage(NCV)detection red light.
5
NCVgreen light: Non ContactACVoltage(NCV)detectiongreen light.
6
LCD display:31/2digits LCD display.
7
HOLD key:Pressthe“HOLD”keyto lock displayvalue, and the “DH”
sign will appear on the display,pressitagain to exit.
8
NCV Key:Pressthe“NCV”key, the meter enters Non ContactAC
Voltage(NCV)detection, the NCVgreen LED light will light up, and the
“NCV”sign will appear on the display,pressitagain to exit.
9
RotarySwitch: Use this switch to select functions and ranges.
10
COM: COM andTemperature “-” Input Jac
k
11
10A: 10AInput Jac
k
12
VΩmA: V/mA/BATT/20uF/ andTemperature “+” Input Jac
k
13
Crust of meter
14
Protective casin
g
3. Safety Information
3-1 The meter is desi
g
ned accordingto IEC-1010 concerningelectronic
measuringinstruments with an over-voltagecategory600V(CATⅢ)and
pollution 2.
3-2 Follow all safetyand operatinginstructions to ensure that the meter is used
safelyand is kept ingood operatingcondition.
3-3 safetysymbols:
Important safetyinformation, refer to the operatingmanual.
Dangerous voltagemaybe presence.
Double insulation (protection Class II)
4. Special Cautions for Operation
4-1 The meters can be safe onl
y
accordingto standard procedures when used
in conjunctions with the supplied test leads. To replace damaged test leads
with onlythe same model or same electric specifications.
4-2Toavidriskof electric shock, do not use the meters before the cover is in
place.
4-3 The rangeswitchshouldberight position for the testing.
4-4 To avoid electric shock and damagingthe instruments, the input signals are
forbidden to exceed the specified limits.
4-5 When measuringTV set or switched power, attention should be paid to the
possible pulses that maybringdestruction to the circuit.
4-6 Range switch position is forbidden to be changed at random durin
g
measurement.
4-7 T ake caution against shock in the course of measuringvoltagehigher than
DC 60V &AC30V.
4-8 Protection fuse should be replaced onlywith same type and same
specification.
4-9After operation is finished, set function switch at OFF rangetosavebatter
y
power.
4-10 If the meter is without usageforlongtime, take out batteryto avoid
damagebybatteryleakage.
5. GENERAL SPECIFICATIONS
5-1 Max Voltage between input terminal and Earth Ground: CAT Ⅲ 600V
5-2 Over-range Indication: display“1”or“-1”forthesignificant digit.
5-3Automatic displayof negative polarity“-” .
5-4 Low BatteryIndication: “ ”displayed.
5-5 Display:31/2digit LCD with a max. readingof 1999.
5-6 Manual range control
5-7Auto Power Off: The meter will switch to standbymode when power on
after approx. 30 minutes. Rotate the rotaryswitch to OFF position, then
power on to exit standbymode.
5-8Auto LCD backlight
5-9 Fuse protection: 200mA/250V PPTC Resettable Fuse
5-10 Power supply:9Vbatter
y
(
6F22 or NEDA 1604
)
5-11 OperatingTem p . : 0℃ to 40℃(relative humidity<85%
)
5-12 Storage Temp.:-10℃ to 50℃((relative humidity<85%
)
5-13 Guaranteed precision Temp.: 23±5℃(relative humidity<70%
)
5-14 Dimension: 150x106x36mm
5-15 Weight: approx. 250
g
(
includingbatter
y)
6. TestingSpecifications
A
ccuracyis specified for a period ofyear after calibration and at 18℃ to 28℃
(
64℉ to 82℉)with relative humidityto 70%.
6-1 DCVoltage
Range Resolution Accurac
y
2V 1mV
±(0.5% of rdg+2digits
)
20V 10mV
200V 100mV
600V 1V ±
(
0.8% of rdg+2digits
)
-- Impedance: 1MΩ
-- Overload protection: 600V DC orACrms
6-2ACVoltage
Range Resolution Accurac
y
200V 100mV
±
(
1.2% of rdg+3digits
)
600V 1V
-- Impedance: 1MΩ
-- Overload protection: 600V DC orACrms
-- FrequencyRange: 40 to 400Hz
-- Response: average, calibrated in rms of sine wave
6-3 DC Current
Ran
g
e Resolution Accurac
y
200mA 100μA±
(
1.2% of rdg+2digits
)
10A 10mA ±(2.0% of rdg+3digits
)
-- Overload protection: 200mA/250V PPTC Resettable Fuse
Note: 10
A
range is not fused, 10Aup to 10 seconds
6-4
A
C Current
Ran
g
e Resolution Accurac
y
200mA 100μA±
(
1.5% of rdg+3digits
)
10A 10mA ±(2.5% of rdg+5digits
)
-- Overload protection: 200mA/250V PPTC Resettable Fuse
Note: 10
A
range is not fused, 10Aup to 10 seconds
-- Frequenc
y
Range: 40 to 400Hz
-- Response: average, calibrated in rms of sine wave
6-5 Resistance
Ran
g
e Resolution Accurac
y
200Ω 0.1Ω ±(1.0% of rdg+3digits
)
2kΩ 1Ω
±
(
1.0% of rdg+2digits
)
200kΩ 100Ω
2MΩ 1kΩ ±
(
1.5% of rdg+3digits
)
-- Overload protection: 250VDC orACrms
6-6 Capacitance
Ran
g
e Accurac
y
Resolution
20µF ±
(
2.5% of rdg+5digits
)
10nF
-- Overload protection: 200mA/250V PPTC Resettable Fuse
6-7 Temperature
Range Accurac
y
Resolution
℃
-20~150℃ ±
(
3℃+ 1digit
)
1℃
150~1000℃ ±
(
3% of rdg+2digits
)
-- NiCr-NiSi K-type sensor
-- Overload protection: 200mA/250V PPTC Resettable Fuse
6-8 Batterytest
Ran
geA
ccurac
y
Load current Resolution
±(5.0% of rdg+5digits
)
A
pprox. 50mA 1mV
A
pprox. 10mA 10mV
-- Overload protection: 200mA/250V PPTC Resettable Fuse
6-9 Diode andAudible continuitytest
Ran
g
e Description Test Condition
Displa
y
read approximatel
y
forward voltageofdiode
Forward DC current
approx. 1m
A
Reversed DC voltage
approx. 3V
Built-in buzzer sounds if
resistance is less than 50Ω
Open circuit volta
g
e
approx. 3V
Overload protection: 250V DC orACrms
6-10 Non ContactACVoltage(NCV)detection
Test voltagerange: 90V～1000VACrms
TheNCVredLEDlight andgreen LED light will light up alternatelytogether
with sound.
7. OPERATING INSTRUCTIONS
7-1 Attention before operation
7-1-1 Check battery. When the battery voltage drop below proper operation
range, the “
” symbol will appear on the LCD display and the battery need to
changed.
7-1-2 Pa
y
attention to the “ ” besides the inputjack which shows that the
input voltage or current should be within the specified value.
7-1-3 The range switch should be positioned to desired range for measurement
before operation.
7-2 Measuring DCVoltage
7-2-1 Connect the black test lead to COM
j
ack and the red to VΩmAjack.
7-2-2 Set the rotaryswitch at the desired “V ” rangeposition.
7-2-3 Connect test leads across the source or load under measurement.
7-2-4 You canget readingfrom LCD. The polarityof the red lead connection
will be indicated alongwith the DC voltage value.
NOTE:
1. When the value scale to be measured is unknown beforehand, set the range
selector at the highest position.
2. When onl
y
the figure“1” or“-1” isdisplayed, it indicatesover-range situation and the
higher range hasto be selected.
3. “
” means you can’t input the voltage more than 600V, it’s possible to show
higher voltage, but it may destroy the inner circuit or pose a shock.
4. Be cautious a
g
ainst shock when measuringhighVoltage.
7-3 Measuring
ACV
oltage
7-3-1 Connect the black test lead to COM
j
ack and the red to VΩmAjack.
7-3-2 Set the rotaryswitch at the desired “V ” rangeposition.
7-3-3 Connect test leads across the source or load under measurement.
7-3-4 You canget readingfrom LCD. The polarityof the red lead connection
will be indicated alongwith the DC voltage value.
NOTE:
1. When the value scale to be measured is unknown beforehand, set the range
selector at the highest position.
2. When onlythe figure“1” or“-1” isdisplayed, it indicatesover-range situation and the
higher range ha
s
to be selected.
3. “
” means you can’t input the voltage more than 600V, it’s possible to show
higher voltage, but it may destroy the inner circuit or pose a shock.
4. Be cautious a
g
ainst shock when measuringhighVoltage.
7-4 Measuring DC Current
7-4-1 Connect the black test lead to COMjack and the red to theVΩmAjack
for a maximum 200mA current , for a maximum 10A current, move the red lead
to the 10Ajack.
7-4-2 Set the rotaryswitch at the desired “A ” rangeposition.
7-4-3 Connect test leads in series with the load under measurement.
7-4-4 You canget readingfrom LCD. The polarityof the red lead connection
will be indicated alongwith the DC current value.
NOTE:
1. When the value scale to be measured is unknown beforehand, set the range
selector at the highest position.
2. When onlythe figure“1” or“-1” is displayed, it indicates over-rangesituation
and the higher range has to be selected.
3. “ ” means the socket mA’s maximum current is 200mA and 10A’s
maximum current is 10A, over 200mAcurrent can be protected bythe PPTC
resettable fuse, but the 10Arangeisnotfused.
4. On the 10Arange, the measuringtime should be less than 10 seconds to
prevent precision from affectin
g
bycircuit heating.
7-5 Measuring
A
C Current
7-5-1 Connect the black test lead to COM
j
ack and the red to theVΩmAjack
for a maximum 200mA current , for a maximum 10A current, move the red lead
to the 10Ajack.
7-5-2 Set the rotaryswitch at the desired “A ” range position.
7-5-3 Connect test leads in series with the load under measurement.
7-5-4 You canget readingfrom LCD. The polarityof the red lead connection
will be indicated alongwith the DC current value.
NOTE:
1. When the value scale to be measured is unknown beforehand, set the range
selector at the highest position.
2. When onlythe figure“1” or“-1” is displayed, it indicates over-rangesituation
and the higher range has to be selected.
3. “ ” means the socket mA’s maximum current is 200mA and 10A’s
maximum current is 10A, over 200mAcurrent can be protected bythe PPTC
resettable fuse, but the 10Arangeisnotfused.
4. On the 10Arange, the measuringtime should be less than 10 seconds to
prevent precision from affectingbycircuit heating.
7-6 Measuring Resistance
7-6-1 Connect the black test lead to COM
j
ack and the red to VΩmAjack.
7-6-2 Set the rotaryswitch at the desired “Ω”rangeposition.
7-6-3 Connect test leads across the resistance under measurement.
7-6-4 You canget readingfrom LCD.
NOTE: Max. input overload: 250V rms＜10sec
1. When onlythe figure “1” or “-1” is displayed, it indicates over-rangesituation
and the higher range has to be selected.
2. For measuringresistance above 1MΩ, the mete maytake a few seconds to
g
et stable reading.
3. When the input is not connected, i.e. at open circuit, the figure “1” or “-1” will
be displayed for the over-range condition.
4. When checkingin-circuit resistance, be sure the circuit under test has all
power removed and that all capacitors have been discharged fully.
7-7 Measuring Capacitance
7-7-1 Connect the black test lead to COM
j
ack and the red toVΩmAjack.
7-7-2 Set the rotaryswitch at the desired “20uF” rangeposition.
7-7-3 Connect test leads across the capacitance under measurement.
7-7-4 You canget readingfrom LCD.
NOTE: Capacitors should be discharged before beingtested.
7-8 Measuring Temperature
7-8-1 Connect the black banana plugof the sensor to COMjack and the
red banana plugto theVΩmAjack.
7-8-2 Set the rotary switch at the desired “ ” range position.
7-8-3 Put the sensor probe into the temperature field under measurement.
7-8-4 You can
g
et readingfrom LCD.
NOTE:
1. The accessoryof the meter WRNM-010 type contact thermocouple limit
temperature is 250
(
300 shortly), please use special probe for test
higher temperature.
2. Please don't change the thermocouple at will, otherwise we can'tguarantee
to measure accuracy.
3. Please don’t importingthe voltage in the temperature function.
7-9 Battery Testing
7-9-1 Connect the black test lead to COM
j
ack and the red toVΩmAjack.
7-9-2 Set the rotary switch at the desired “
”or“ ” range position to
test 1.5
V
or 9V battery.
7-9-3 Connect test leads across the source or load under measurement.
7-9-4 You can
g
et readingfrom LCD.
7-10 Diode &
A
udible continuity Testing
7-10-1 Connect the black test lead to COM
j
ack and the red toVΩmAjack.
7-10-2 Set the rotary switch at the “
” range position.
7-10-3 On diode ran
g
e, connect the test leads across the diode under
measurement, displayshows the approx. forward voltage of this diode.
7-10-4 OnAudible continuityrange, connect the test leads to two point
of circuit, if the resistance is lower than approx. 50Ω, the buzzer sounds.
NOTE: Make sure the power is cut off and all capacitors need to be discharged
under this measurement.
7-11 Non ContactACVoltage detection
7-11-1 Power on the meter, on an
y
range, press the “NCV”key,themeter
enters Non ContactACVoltage(NCV)detection, the NCVgreen LED light will
light up, and the “NCV”sign will appear on the display.
7-11-2 Hold the Meter so that the mater’s top is verticallyand horizontall
y
centered and contactingthe conductor, when the live voltage ≥90VAC
rms, the NCV red LED light andgreen LED light will light up alternatel
y
together with sound.
NOTE:
1. Even without LED indication, the voltagemaystill exist. Do not relyon
non-contact voltage detector to determine the presence of voltagewire.
Detection operation maybe subject to socket design, insulation thickness and
different type and other factors.
2. When the meter input terminals presence voltage, due to the influence of
presence voltage, voltagesensingindicator mayalso be bright.
3. Keep the meter awayfrom electrical noise sources duringthe tests, i.e.,
florescent lights, dimmable lights, motors, etc.. These sources can trigger
Non-ContactACVoltage detection function and invalidate the test.
8. Battery replacement
1) When the battery voltage drop below proper operation range the "
"
s
y
mbol will appear on the LCD displayand the batteryneed to changed.
2)Before changingthe battery, set the selector switch to “OFF”position.
Open the cover of the batterycabinet bya screwdriver.
3)Replace the old batterywiththesametype batter
y
(
9V 6F22 or NEDA
1604).
4)Close the cover of the batterycabinet and fasten the screw.
9. Maintenance
9-1 Before attemptin
g
to remove the batterydoor or open the case, be sure
that test leads have been disconnected from measurement circuit top avoid
electric shock hazard.
9-2 You must replace the test leads if the lead is exposed, and should adopt
the leads with the same specifications as origin.
9-3 Use onlymoist fabric or small amount of detergent but not chemical
solution for cleaning.
9-4 Do not use the meter before the back cover is properlyclosed and screw
secured. Upon anyabnormality, stop operation immediatelyand send the
meter for maintenance.
9-5 Please take out the batterywhen not usingfor a longtime.
10.
A
ccessories
[1] Test Leads: electric ratin
g
1000V 10A
[2] “K” type thermocouple sensor probe
[3] Operator’s Manual
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