Brymen BM789 User manual

USER'S
MANUAL
BM789
BM786
BM785
Digital
Multimeter

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1) SAFETY
This manual contains information and warnings that must be followed for operating the
meter safely and maintaining the meter in a safe operating condition. If the meter is
used in a manner not specified by the manufacturer, the protection provided by the
meter may be impaired.
Observe proper safety precautions when working with voltages above 30 Vrms, 42.4
Vpeak or 60 VDC. These voltage levels pose a potential shock hazard to the user. Do
not expose this product to rain or moisture. The meter is intended only for indoor use.
Keep your hands/fingers behind the hand/finger barriers (of the meter and the test
probe assembly, where applicable) that indicate the limits of safe access of the hand-
held parts during measurements. Inspect lead wires, connectors, and probes for
damaged insulation or exposed metal periodically. If any defects are found, replace
them immediately. Only use the test probe assembly provided with the meter or a UL
Listed test probe assembly to the same meter ratings or better.
Optional offer premium test probe assembly using silicone lead wire insulation, at
agent’s discretion, is equipped with white inner insulation layers as wear indicators.
Replace them immediately if any of the white layers has become visible.
Disconnect the test leads from the test points before changing functions.
The meter meets IEC/EN/CSA_C22.2_No./UL standards of 61010-1 Ed. 3.0, 61010-2-
030 Ed. 1.0, 61010-2-033 Ed. 1.0 to Measurement Categories CAT III 1000V and CAT
IV 600V ac & dc.
The accompanied test probe assembly meets IEC/EN/CSA_C22.2_No./UL standards
of 61010-031 Ed. 2.0 to the same meter ratings or better. The 61010-031 requires
exposed conductive test probe tips to be ≤4mm for CAT III & CAT IV ratings. Refer to
the category markings on your probe assemblies as well as on the add-on accessories
(like detachable Caps or Alligator Clips), if any, for applicable rating changes.
INTERNATIONAL SYMBOLS
Marking of Electrical and Electronic Equipment (EEE). Do not dispose of this
product as unsorted municipal waste. Contact a qualified recycler
Refer to the explanation in this Manual
Possibility of electric shock

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Earth (Ground)
Meter protected throughout by Double Insulation or Reinforced insulation
Fuse
Direct Current (DC)
Alternating Current (AC)
3Three-phase Alternating Current
Application around and removal from hazardous live conductors is permitted
BRIEF INFORMATION ON MEASUREMENT CATEGORIES
Measurement Category IV is applicable to test and measuring circuits connected at
the source of the building’s low-voltage MAINS installation. Examples are
measurements on devices installed before the main fuse or circuit breaker in the
building installation.
Measurement Category III is applicable to test and measuring circuits connected to
the distribution part of the building’s low-voltage MAINS installation. Examples are
measurements on distribution boards (including secondary meters), circuit-breakers,
cables, bus-bars, junction boxes, switches, socket-outlets, stationary motors in the
fixed installation, and equipment for industrial use.
Measurement Category II is applicable to test and measuring circuits connected
directly to utilization points (socket outlets and similar points) of the low-voltage MAINS
installation. Examples are measurements on MAINS CIRCUITS of household
appliances, portable tools and similar equipment.
2) EUROPEAN DIRECTIVES
The instruments conform to EUROPEAN Low-Voltage Directive 2014/35/EU,
Electromagnetic Compatibility Directive 2014/30/EU and RoHS 2 Directive 2011/65/EU
plus amendment Directive (EU) 2015/863.
3) PRODUCT DESCRIPTION
This user's manual uses only representative model(s) for illustrations. Please refer
detailed specifications for function availability to each model.

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1) 4-5/6 digits 60000 counts
display
2) Push-buttons for special
functions & features
3) Selector to turn the Power On
or Off and Select a function
4) Positive Input Jack for T2 and
mA/µA functions
5) Positive Input Jack for all
functions EXCEPT T2, A and
µA/mA
6) Common/ Negative (Ground
reference) Input Jack for all
functions EXCEPT T2
7) Positive Input Jack for A
function while Negative for T2
Analog bar-graph
The analog bar graph provides a visual indication of measurement like a traditional
analog meter needle. It is excellent in detecting faulty contacts, identifying
potentiometer clicks, and indicating signal spikes during adjustments.
4) OPERATION
Note: Before and after hazardous voltage measurements, test the voltage function on

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a known source such as line voltage to determine proper meter functioning.
AutoV (LoZ) (Model 789 only)
Inputs are made via the test lead terminals V-COM. AutoV automatically selects
measurement function of DCV or ACV based on their input levels via the test leads.
The input also provides a low ramp-up impedance (LoZ) to drain ghost voltages.
◎With no input, the meter displays “Auto” when it is ready.
◎When a signal above the voltage threshold of 1V DC or AC up to the rated 1000V is
present, the meter displays the voltage value in appropriate DC or AC, whichever
larger in peak magnitude.
◎Push-button features of only HOLD, AutoHold, EF and Backlight are available in
AutoV mode.
Note:
1) Ghost-voltage Buster: Ghost-voltages are unwanted stray signals coupled from
adjacent hard signals, which confuse common multimeter voltage measurements. The
AutoV mode provides low (ramp-up) input impedance (approx. 2.1kΩ at low voltage) to

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drain ghost voltages leaving mainly hard signal values on meter readings. It is an
invaluable feature for precise indication of hard signals, such as distinguishing between
hot and open wires (to ground) in electrical installation applications.
2) AutoV Mode input impedance increases abruptly from initial 2.1kΩ to a few
hundred kΩ’s on high voltage hard signals. “LoZ” displays on the LCD to remind the
users of being in such a low impedance mode. Peak initial load current, while probing
1000VAC for example, can be up to 673mA (1000V x 1.414 / 2.1kΩ), decreasing
abruptly to approx. 2.1mA (1000V x 1.414 / 670kΩ) within a fraction of a second. Do
not use AutoV mode on circuits that could be damaged by such low input impedance.
Instead, use rotary selector or high input impedance voltage modes to minimize
the test loadings for such circuits.
ACV; VFD-ACV; dBm (Model 789 only)
Inputs are made via the test lead terminals V-COM. Press the SELECT button
momentarily to select the subject functions in sequence. Last selection will be saved as
power up default for repeat measurement convenience.
Note: In dBm function, power up default reference impedance will be displayed for 1
second before displaying the dBm readings. Press dBm-  (RANGE) button
momentary to select different reference impedance of 4, 8, 16, 32, 50, 75, 93, 110,
125, 135, 150, 200, 250, 300, 500, 600, 800, 900, 1000, up to 1200  . Last selection
will be saved as power up default for repeat measurement convenience.

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~Hz Line Frequency
Press the ~Hz button momentarily to switch to Line Frequency function. It is only
available to the functions as in the table below. Input sensitivity varies automatically
with the function range selected while the ~Hz function is being activated. Level 0 is the
highest sensitivity while LEVEL 3 is the lowest. Press momentarily the ~Hz (LEVEL)
button can manually select the available Trigger Levels (see table below) in sequence.
Press the ~Hz button for one-second-or-more to leave Line Frequency function.
TRIGGER
ACV/dBm/DCV/AC+DCV
VFD-ACV
A
mA
A
LEVEL 0
6V
600A
60mA
6A
LEVEL 1
60V
6000A
600mA
10A
LEVEL 2
600V
600V
LEVEL 3
1000V
1000V
Note: It is recommended to direct measure the signals (voltage or current) in auto-
ranging mode before activating the ~Hz function right in that range to get the most
appropriate trigger level automatically. If the ~Hz reading is unstable, select lower
sensitivity to avoid possible electrical noises. If the reading shows zero, select higher
sensitivity to measure.

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DCV; DC+ACV
Inputs are made via the test lead terminals V-COM. Press the SELECT button
momentarily to select the subject functions in sequence. Last selection will be saved as
power up default for repeat measurement convenience.
DCmV; ACmV; DC+ACmV; Logic-level Hz; Logic-level Duty %; dBm (Model 789
only)
Inputs are made via the test lead terminals V-COM. Press the SELECT button
momentarily to select the subject functions in sequence. Last selection will be saved as
power up default for repeat measurement convenience.

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Note: In dBm function, power up default reference impedance will be displayed for 1
second before displaying the dBm readings. Press dBm-  (RANGE) button
momentary to select different reference impedance of 4, 8, 16, 32, 50, 75, 93, 110,
125, 135, 150, 200, 250, 300, 500, 600, 800, 900, 1000, up to 1200  . Last selection
will be saved as power up default for repeat measurement convenience.

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Resistance; BeepLitTM Continuity; nS Conductance (Models 789 & 786
only)
Inputs are made via the test lead terminals V-COM. Press the SELECT button
momentarily to select the subject functions in sequence. Last selection will be saved as
power up default for repeat measurement convenience.
◎ BeepLitTM Continuity
This function is having improved convenience for checking wiring connections and
operation of switches. Resistance threshold is being used. A continuous beep tone
together with display backlight flashing indicate a complete wire. Such audible and
visible indications improve continuity readabilities in noisy working environments.
◎nS Conductance (Models 789 & 786 only)
nS Conductance is the inverse of Resistance. That is, S=1/  or nS=1/G  . It virtually
extends the Resistance measurements to the order of Giga-Ohms for leakage
measurements.
Note: Using Resistance, BeepLitTM Continuity or nS Conductance function in a live
circuit will produce false results and may damage the meter. In many cases, the
suspected component(s) must be disconnected from the circuit to obtain an accurate
measurement reading.

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Capacitance; BeepLitTM Diode
Inputs are made via the test lead terminals V-COM. Press the SELECT button
momentarily to select thesubject functions in sequence. Last selection will be saved as
power up default for repeat measurement convenience.
◎BeepLitTM Diode
●Reading indication: Forward voltage drop (forward biased) for a good silicon diode
is between 0.400V to 0.900V. A higher reading indicates a leaky diode (defective). A
zero reading indicates a shorted diode (defective). An over-range display indicates an
open diode (defective). Reverse the test leads connections (reverse biased) across the
diode. The digital display shows over-range if the diode is good. Any other readings
indicate the diode is resistive or shorted (defective).
●Beep-Alert & BeepLitTM indication: When the display reading drops across 0.850V,
the meter alerts a short beep to signal a reasonable forward voltage drop of common
diodes. However, if the reading further drops below 0.100V, the meter gives a
continuous beep tone together with flashing display backlight to indicate a shorted
diode or a complete wire. It is similar to that of BeepLitTM Continuity function but
BeepLitTM Diode, instead, is based on voltage threshold to indicate a complete wire.
Note:

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1) Discharge capacitor(s) before making capacitance measurements. Large value
capacitors should be discharged through an appropriate resistance load.
2) Using BeepLitTM Diode or Capacitance function in a live circuit will produce false
results and may damage the meter. In many cases, the suspected component(s) must
be disconnected from the circuit to obtain an accurate measurement reading.
Temperature: T1 (Models 789 & 786 only); +T2 (Model 789 only)
T1 inputs are made via the input terminals V-COM. Press SELECT button momentarily
can toggle between °C (Celsius) and °F (Fahrenheit) readings when enabled. Last
selection will be saved as power up default for repeat measurement convenience.
Additional T2 inputs are made via the input terminals -. Press RANGE (T1-
T2) button momentarily to select T1, T2 and T1-T2 in sequence.
◎Enabling °F and/or °C readings
1) Enabling both °F and °C readings: Press-and-hold EF button to power on the
meter. The meter displays “C-F”to acknowledge both °F and °C readings are enabled.
2) Enabling °C readings only: Repeat step #1 when needed. Turn on the meter to
temperature function. Select readings in °C and then turn the meter off. Press-and-hold
CREST button to power on the meter again. The meter displays “C”to acknowledge °C
readings only is enabled.
3) Enabling °F readings only: Repeat step #1 when needed. Turn on the meter to
temperature function. Select readings in °F and then turn the meter off. Press-and-hold
CREST button to power on the meter again. The meter displays “F”to acknowledge °F
readings only is enabled.

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Note:
1) Temperature accuracies assume meter interior has the same temperature
(isothermal stage) of the ambient for a correct junction voltage compensation. Allow the
meter and the type-K probe set to reach isothermal stage for a significant change of
ambient temperature. It can take up to an hour for changes > 5°C.

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2) Beware +/- polarities of the banana-plug when using the type-K temperature bead-
probe Bkp60.
3) Banana-pins to type-K socket adapter Bkb32 (Optional purchase) can be used to
adapt other type-K probes with standard miniature plugs. However, the adapter
becomes part of the measurement isothermal block when in use, and should be
included in the overall isothermal considerations to minimize erratic readings.

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A Current
Inputs are made via the input terminals -COM. Press the SELECT button
momentarily to select DC, AC,DC+AC in sequence. Last selection will be saved as
power up default for repeat measurement convenience of all current functions.
µA Current
Inputs are made via the input terminals -COM. Press the SELECT button
momentarily to select DC, AC, DC+AC in sequence. Last selection will be saved as
power up default for repeat measurement convenience of all current functions.

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mA Current
Inputs are made via the input terminals -COM. Press the SELECT button
momentarily to select DC, AC, DC+AC and %4-20mA (Model 789 only) in sequence.
Last selection will be saved as power up default for repeat measurement convenience
of all current functions.
EF-Detection of Electric Field
Press EF button momentarily to enter EF-Detection function. Defaults at high
sensitivity EF-H. The meter displays “EF-H” when it is ready. If it is too sensitive for
your applications, press EF button momentarily to select lower sensitivity “EF-L”. The
detected Electric Field strength is indicated as a series of bar-graph segments on the
display plus variable beep tones. Press EF button for one-second-or-more to exit EF-
Detection function.
◎Non-Contact EF-Detection (NCV): An antenna is located along the top-right
corner which detects the electric field surrounding energized conductors. It is ideal for
tracing live wiring connections, locating wiring breakages and to distinguish between
live and earth connections.
◎Probe-Contact EF-Detection (Single-pole): For more precise indication of live
wires, such as distinguishing between Live and Ground connections, use one single
test-probe to test via terminal COM for direct metal contact probing to achieve the most

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distinctive indications.
LCD Backlight
Press the SELECT button for one-second-or-more to toggle the LCD backlight. The
LCD backlight goes off automatically after idling for approximately 16 minutes to extend
battery life.
Manual or Auto-ranging

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For most auto-ranging functions (LCD “ ” turns on by default), press the RANGE
button momentarily to override and select manual-ranging. The meter will remain in the
range it was in, the LCD “ ” turns off. Press the button momentarily again to select
the next range. Press RANGE button for one-second-or-more to resume auto-ranging.
Note: Manual-ranging feature is not available to the Auto-V, dBm, Capacitance & Hz
functions.
HOLD
HOLD feature freezes the display for later view. LCD “ ” turns on. Press the HOLD
button momentarily to toggle the HOLD feature.
AutoHold Real-Read™
AutoHold feature displays the last latched stable-reading for later view when the test
leads are removed from the test points after a significant-measurement session. Real-
Read™ is to show real-time readings during the significant-measurement session to
avoid “blind”measurements. Press the AutoHold button for one-second-or-more
to toggle the AutoHold feature on. LCD “ ” turns on. Availability: Resistance,
Continuity, LoZ AutoV, VFD Volts, Voltage and Current functions.
◎Significant-measurements (readings) are >5% of range in Voltage and Current
functions, or non-OL in Resistance function.
◎Stable-reading is a significant-measurement reading having ≤30 counts in
difference with its two immediate preceding measurement readings.
◎Significant-measurement readings are being displayed in real time (Real-Read™);
“- - - - -”is being displayed while awaiting significant-measurements.
◎The AutoHold gives a short-beep with a flashing “ ” when a stable-reading is
successfully latched ready for later display. If any of the further significant-
measurement readings differs from the latched reading by >30 counts, the latched-
reading will be reset waiting to re-latch a new stable-reading.
◎After a significant-measurement session, AutoHold gives a short-beep and
displays the latched-reading. The reading flashes to emphasize it is on hold to avoid
confusions.
◎The AutoHold gives 3 short-beeps and “- - - - -”flashes to indicate a null capture
after a significant-measurement. It represents no stable-reading is being latched or that
has been reset after further encountering unstable signal changes to avoid displaying
misleading readings.

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Note:Make sure both test probes are making good contacts simultaneously when
using the AutoHold feature. Single probe contact may lead to latching floating-signal
readings. Removing both probes from the test points simultaneously largely avoids the
mis-latching of an unwanted floating-signal.
MAX/MIN/AVG Record mode
Press REC button momentarily to activate MAX/MIN/AVG recording mode. LCD “
MAX AVG MIN”turn on. The meter beeps when new MAX (maximum) or MIN
(minimum) reading is updated. Press the button momentarily to read the MAX, MIN,
AVG and MAXAVGMIN (active measurement) readings in sequence. Press REC
button for one-second-or-more to exit this mode. Auto-Power-Off is disabled
automatically in this mode.
Relative mode
Relative mode allows the user to offset the meter consecutive measurements with
the displaying reading as the reference value. LCD “ ” turns on. Press the button
momentarily to toggle Relative mode.
CREST mode
Press CREST button momentarily to activate CREST mode (Instantaneous PEAK-
HOLD) to capture current or voltage peak values in duration as short as 0.25ms. LCD
& MAX turn on. The meter beeps when new MAX (maximum) or MIN (minimum)
reading is updated. Press the button momentarily to toggle the MAX and MIN
readings. Press the button for one-second-or-more to exit this mode. Auto-Power-Off is
disabled automatically in this mode. Availability: Voltage and Current functions.
Beep-Jack™ Input Warning
The meter beeps as well as displays “InEr” to warn the user against possible damage
to the meter due to improper connections to the A, mA, or A input jacks when another
function, especially a voltage function, is selected.
Auto-Power-Off (APO)
The Auto-Power-off (APO) mode turns the meter off automatically to extend battery life
after approximately 30 minutes of no rotary switch or push button operations. To wake
up the meter from APO, press the SELECT button momentarily and release, or turn the
rotary switch OFF and then back on. Always turn the rotary switch to the OFF position
when the meter is not in use

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Power-on Options
◎Disabling APO
Press-and-hold the SELECT button while powering on the meter can disable APO
feature temporarily during the power-on session. The LCD will display “dSAPO”to
confirm selection before the SELECT button is released.
◎Disabling beep tone
Press-and-hold the RANGE button while powering on the meter can toggle the beep
tone OFF or ON in sequence. The meter confirms selection by displaying “dSbEP”for
beeper OFF (disabled) or “EnbEP”for beeper ON (enabled), before the RANGE button
is released. Last selection will be saved as power up default. When disabled, most
operation beep tones are turned off except those for BeepLitTM Continuity and
BeepLitTM Diode functions.
◎Shortening APO idling time for inspection
Press-and-hold the (Relative) button while powering on the meter can shorten the
APO idling time to approximately 8 seconds temporarily during the power-on session. It
is designed mainly for production inspection.
◎Disabling/Enabling oC or oF function availability
See Temperature measurement operation description for details.
5) MAINTENANCE
Note: To avoid electrical shock, disconnect the meter from any circuit, remove the test
leads from the input jacks and turn OFF the meter before opening the case. Do not
operate with open case.
Trouble Shooting
If the instrument fails to operate, check batteries and test leads etc., and replace as
necessary. Double check operating procedure as described in this user’s manual.
Refer to the LIMITED WARRANTY section for obtaining calibration, repairing or
warranty service.
Accuracy and Calibration
Accuracy is specified for a period of one year after calibration. Periodic calibration at
intervals of one year is recommended to maintain meter accuracy.