BM22, BM25 & BM27
USER'S MANUAL
1) PRODUCT DESCRIPTION
Note: Top of the line model is used as representative for illustration
purposes. Please refer to your respective model for function
availability.
1) LCD display
2) Rotary Selector to Select additional functions (BM27 & BM22
only), and to turn the Power On or Off (BM22 only). BM25 does not
have a physical Rotary Selector.
3) Push-button to Select additional functions (all models), and to
switch the Power On or Off (BM27 & BM25 only)
4) Input for all functions, or otherwise specified. Red test lead for
positive (+) polarity and Black test lead for Ground reference (-)
2) SAFETY
Terms in this manual
WARNING
identifies conditions and actions that could result in serious injury or even death to the user.
CAUTION
identifies conditions and actions that could cause damage or malfunction in the instrument.
This manual contains information and warnings that must be followed for operating the instrument safely and
maintaining the instrument in a safe operating condition. If the instrument is used in a manner not specified by the
manufacturer, the protection provided by the instrument may be impaired. The meter is intended only for indoor
use. The meter is protected, against the users, by double insulation per EN61010-1, IEC61010-1, CSA C22.2 No.
1010.1-92 and UL61010B-1 to CAT III 300V & CAT II 600V (CAT II 450V for model BM25).
Measurement Category III (CAT III)
is for measurements performed in the building installation. Examples are
measurements on distribution boards, circuit-breakers, wiring, including cables, bus-bars, junction boxes, switches,
socket-outlets in the fixed installation, and equipment for industrial use and some other equipment, for example,
stationary motors with permanent connection to the fixed installation.
Measurement Category II (CAT II)
is for measurements performed on circuits directly connected to the low
voltage installation. Examples are measurements on household appliances, portable tools and similar equipment.
WARNING
To reduce the risk of fire or electric shock, do not expose this product to rain or moisture. To avoid electrical shock
hazard, observe the proper safety precautions when working with voltages above 60 VDC or 30 VAC rms. These
voltage levels pose a potential shock hazard to the user. Do not touch test lead tips or the circuit being tested
while power is applied to the circuit being measured. Keep your fingers behind the finger guards of the test leads
during measurement. Inspect test leads and probes for damaged insulation or exposed metal before using the
instrument. If any defects are found, replace them immediately.
2
INTERNATIONAL ELECTRICAL SYMBOLS
!
Caution ! Refer to the explanation in this Manual
Caution ! Risk of electric shock
Earth (Ground)
Double Insulation or Reinforced insulation
Fuse
AC--Alternating Current
DC--Direct Current
3) CENELEC DIRECTIVES
The instrument conforms to CENELEC Low-voltage directive 73/23/EEC and Electromagnetic compatibility
directive 89/336/EEC
4) OPERATION
Note: All function operations described hereafter are via the Red test lead for positive (+) polarity and Black test
lead for Ground reference (-), or otherwise specified
4-1) FUNCTIONS IN “Auto V.
Ω
Ω
Ω
Ω
” POSITION (BM27 & BM25 only)
-Quick Start (BM27 & BM25 only)
AutoCheck
TM
mode is the default function in
“
Auto V.
Ω
” position. Press the SELECT button momentarily to select
and step through the functions:
AutoCheck
TM
→Continuity→EF→ACV→DCV→
Ω
→Hz→Cx→AutoCheck
TM
-AutoCheck
TM
mode (BM27 & BM25 only)
This innovative AutoCheck
TM
feature automatically selects measurement function of DCV, ACV or Resistance (
Ω
)
based on the input via the test leads.
●With no input, the meter displays “Auto” when it is ready.
●With no voltage signal but a resistance below 6M
Ω
is present, the meter displays the resistance value. When
below 25
Ω
is present, the meter (BM27only) further gives a continuity beep tone.
●When a signal above the threshold of DC 1.2V or AC 1.5V up to the rated 600V (450V for BM25) is present, the
meter displays the appropriate voltage value in DC or AC, whichever larger in peak magnitude.
●
Overload-Alert Feature:
When above rated 600V (450V for BM25) is present, the meter displays “OL” with a
warning beep tone. Disconnect the test leads from the signal immediately to avoid hazards.
Note:
*Range-Lock Feature:
When a measurement reading is being displayed in AutoCheck
TM
mode, press the
SELECT
button momentarily
1 time
can lock the function-range it was in. The LCD annunciator
“
”
turns
off. Range-lock can speed up repetitive measurements. Press the
SELECT
button momentarily again to return to
AutoCheck
TM
mode.
*Hazardous-Alert:
When making resistance measurements in AutoCheck
TM
mode, an unexpected display of
voltage readings alerts you that the part under test is still energized.
*
AutoCheck
TM
nominal input impedances are slightly lower than that of common digital multimeters. They are, in
fact, more similar to that of most traditional analog multimeters. “LoZ” will display on the LCD to remind the users
in such cases. Although not likely, if such impedance might damage your circuits, use the common impedance (Hi-
Z) voltage mode (BM27 and BM22 only) for making voltage measurements on them.
-Continuity, Audible With Symbolic Display (BM27 & BM25 only)
From AutoCheck
TM
with “Auto” being displayed, press the
SELECT
button momentarily
1 time
to select Continuity
function. The meter displays a symbolic open-switch display “
” when it is ready. Continuity is convenient for
checking wiring connections and operation of switches. A continuous beep tone with a symbolic closed-switch
display “
” indicates a complete circuit. In noisy environments, it is helpful to “see” continuity measurements.
3
-Electric Field EF-Detection (BM27 & BM25 only)
From AutoCheck
TM
with “Auto” being displayed, press the
SELECT
button momentarily
2 times
to select EF-
Detection feature. The meter displays “EF” when it is ready. Signal strength is indicated as a series of bar-graph
segments on the display and variable beep tones.
●
Non-Contact EF-Detection:
An antenna is located at the top left corner of the meter, which detects electric field
surrounds current-carrying conductors. It is ideal for tracing live wiring connections, locating wiring breakage and to
distinguish between live or earth connections.
●
Probe-Contact EF-Detection:
For more precise indication of live wires, such as distinguishing between live and
ground sockets, use the Red (+) test probe for direct contact measurements.
-V and
Ω
Ω
Ω
Ω
of AutoCheck
TM
In Manual Selection (BM27 & BM25 only)
From AutoCheck
TM
with “Auto” being displayed, press the
SELECT
button momentarily
3 times
to select ACV,
4
times
to select DCV and
5 times
to select Resistance (
Ω
) functions of AutoCheck
TM
. Such selected function
remains auto-ranging.
-Frequency And Capacitance (BM27 & BM25 only)
From AutoCheck
TM
with “Auto” being displayed, press the
SELECT
button momentarily
6 times
to select
Frequency (Hz),
7 times
to select Capacitance (F) functions and
8 times
to return to AutoCheck
TM
mode.
Note:
*
Unlike the Line Level Hz Frequency function (for BM27 only) as stated, this (Common) Hz Frequency function is
set only at the highest input sensitivity mainly for measuring small electronic signals of below 20VAC rms.
4-2) OTHER FUNCTIONS
-DCV, ACV & Line-Level Hz functions (BM27 only)
Rotate the rotary selector to the V position selects common impedance (Hi-Z) voltage measurements. DCV is the
default function. Press
SELECT
button momentarily to select ACV. The AC annunciator “
” turns on.
Press
momentarily again to activate the Line-Level Hz function.
Note:
*Line-Level Hz input sensitivity varies automatically with ACV range selected when Line-Level Hz is selected. AC
6V range has the highest and AC 600V range has the lowest sensitivity. Measuring the signal in ACV function
WHILE selecting Line-Level Hz function in that ACV range automatically sets the most appropriate sensitivity for
higher voltage applications. This can avoid electrical noises as in 110/220V line voltage applications for example. If
the reading shows zero due to insufficient signal levels, select Line-Level Hz function BEFORE making
measurements (at AC 6V range) will set the highest sensitivity.
-Diode & 600
Ω
Ω
Ω
Ω
functions (BM27 only)
Rotate the rotary selector to the
/600
Ω
position.
Diode test is the default function. The reading shows the approximate voltage drop across the test leads. Normal
forward voltage drop (forward biased) for a good silicon diode is between 0.400V to 0.900V. A reading higher than
that indicates a leaky diode (defective). A zero reading indicates a shorted diode (defective), and the meter will
give a long beep as continuity warning. An OL indicates an open diode (defective). Reverse the test leads
connections (reverse biased) across the diode. The digital display shows OL if the diode is good. Any other
readings indicate the diode is resistive or shorted (defective).
Press
SELECT
button momentarily selects the lowest 600
Ω
range for lower resistance measurements. It is an
extended range to complement the AutoCheck
TM
Resistance (
Ω
) function.
-DC-
µ
µ
µ
µ
A & AC-
µ
µ
µ
µ
A Micro-Amp functions (BM27 only)
Rotate the rotary selector to the
µ
A position. The display-reading unit is in
µ
A although there is no unit
annunciator on the display. DC-
µ
A is the default function. There is no annunciator for DC. Press
SELECT
button
4
momentarily to select AC-
µ
A. The AC annunciator “
” turns on. These ranges, like other functions, are
protected up to the maximum rated voltages of the meter.
-DCV & ACV functions (BM22 only)
Rotate the rotary selector to the V position selects common impedance (Hi-Z) voltage measurements. DCV is the
default function. The DC annunciator “
” turns on. Press
SELECT
button momentarily to select ACV. The AC
annunciator “
” turns on.
-Resistance, Continuity, Diode & Capacitance functions (BM22 only)
Rotate the rotary selector to the
Ω
Ω
Ω
Ω
/
/
/
position. Resistance “
Ω
Ω
Ω
Ω
”is the default function.
Press
SELECT
button momentarily selects Continuity function. The Audible annunciator “
” turns on. Continuity
is convenient for checking wiring connections and operation of switches. A continuous beep tone indicates a
complete circuit.
Press
SELECT
button momentarily AGAIN selects Diode test function. The annunciator “
” turns on. The
reading shows the approximate voltage drop across the test leads. Normal forward voltage drop (forward biased)
for a good silicon diode is between 0.400V to 0.900V. A reading higher than that indicates a leaky diode
(defective). A zero reading indicates a shorted diode (defective). An OL indicates an open diode (defective).
Reverse the test leads connections (reverse biased) across the diode. The digital display shows OL if the diode is
good. Any other readings indicate the diode is resistive or shorted (defective).
Press
SELECT
button momentarily AGAIN selects Capacitance function.
-Frequency function (BM22 only)
Rotate the rotary selector to the Hz position selects Frequency function.
*
Unlike the Line Level Hz Frequency function (for BM27 only) as stated, this (Common) Hz Frequency function is
set only at the highest input sensitivity mainly for measuring small electronic signals of below 20VAC rms.
4-3) OTHER FEATURES
-Power On & Off
For models BM27 and BM25, press and hold the SELECT button for 1 second and then release to turn the power
ON or OFF. Press and hold the SELECT button for approximately 6 seconds to master reset the system to the
default stage if in case the meter hangs up unexpectedly.
For model BM22, rotate the rotary selector to turn the power ON or OFF.
-Auto Power Off
Models BM27 and BM25 turn off intelligently after approximately 3 minutes of idle measurement readings and no
button/switch activities. Model BM22 turns off automatically after approximately 30 minutes of only no
button/switch activities.
-HOLD and
30ms MAX
features (BM22 only)
The Hold feature freezes the display for later viewing. Press the
HOLD (
MAX
)
button momentarily to activate
or to exit the Hold feature.
The Max feature captures voltage signals that have durations as short as 30ms (milliseconds) within a single
range, and has automatic up range capability. This mode is available in DCV & ACV functions. Press the
HOLD
(
MAX
)
button for 1 second or more to activate or to exit the Max feature.
-Auto-ranging
If the function selected has more than one range, the meter will auto-range to the best range and resolution. No
manual ranging is required.
