Brymen EEVblog BM235 User manual

USER'S
MANUAL
BM235
Revision: 5th March 2016

INTRODUCTION
Congrats on purchasing the EEVblog BM235 mutlimeter. It's a beaut little meter, one of
the safest and ell built meters in a small form factor. You've made a ise choice
buying this instead of some questionable quality cheapie. It should return the favor ith
many years of safe and accurate service.
That UL logo you see stamped on the front of the meter ensures that the meter design
has been independently tested to the latest IEC/UL/EN61010-1 3.0 safety standard.
With the CAT IV rating (exceptional for this size of meter), you can feel confident and
safe that you can use this meter on any high energy mains rated equipment in almost
any scenario.
The highest quality and fully rated silicone test probes have also been provided ith
the meter. They aren't just some cheapies thro n in to make it useful.
Enjoy.
And remember, don't turn it on, take it apart!
Regards
Dave Jones
That EEVblog Bloke
.eevblog.com

SAFET
This manual contains information and arnings that must be follo ed 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.
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.
WARNING
To reduce the risk of fire or electric shock, 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, here applicable) that indicate the limits of safe access of the hand-
held parts during measurements. Inspect lead ires, connectors, and probes for
damaged insulation or exposed metal before using the meter. If any defects are found,
replace them immediately. Only use the probe assembly provided ith the meter or a
UL Listed Probe Assembly to the same meter ratings or better.
IEC 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 ell as on
the add-on accessories (like detachable Caps or Alligator Clips), if any, for applicable
rating changes.
Observe proper safety precautions hen orking ith voltages above 33 Vrms, 46.7
Vpeak or 70 VDC. These voltage levels pose a potential shock hazard to the user.
Before and after hazardous voltage measurements, check the voltage function on a
kno n source such as line voltage to determine proper meter functioning.
CAUTION
Disconnect the test leads from the test points before changing functions.

International Electrical Symbols
Marking of Electrical and Electronic Equipment (EEE). Do not dispose of this
product as unsorted municipal aste. Contact a qualified recycler
Caution! Refer to the explanation in this Manual
Caution! Possibility of electric shock
Earth (Ground)
Meter protected throughout by Double Insulation or Reinforced insulation
Fuse
Direct Current (DC)
Alternating Current (AC)
3 Three-phase Alternating Current
Brief Information about Measurement Categories
Measurement Category IV is applicable to test and measuring circuits connected at
the source of the building’s lo -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 lo -voltage MAINS installation. Examples are
measurements on distribution boards (including secondary meters), circuit-breakers,
iring, including cables, bus-bars, junction boxes, s itches, socket-outlets in the fixed
installation, and equipment for industrial use and some other equipment such as
stationary motors ith permanent connection to the fixed installation.
Measurement Category II is applicable to test and measuring circuits connected
directly to utilization points (socket outlets and similar points) of the lo -voltage MAINS
installation. Examples are measurements on MAINS CIRCUITS of household
appliances, portable tools and similar equipment.
2) CENELEC DIRECTIVES
The instruments conform to CENELEC Lo -voltage directive 2006/95/EC,
Electromagnetic compatibility directive 2004/108/EC and RoHS directive 2011/65/EU.

1) 3-5/6 digits 6000
counts LCD display
2) Push-buttons for
special functions &
features
3) Selector to turn the
Po er On or Off and
Select a function
4) Input Jack for 10A
(20A for 30sec) current
function
5) Input Jack for all
functions EXCEPT A,
mA & A current
functions
6) Common (Ground
reference) Input Jack for
all functions
7) Input Jack for A and
mA current function

True RMS
RMS (Root-Mean-Square) is a term used to describe the effective or equivalent
DC value of an AC signal. True RMS is the term hich identifies a DMM that responds
accurately to the effective RMS value regardless of the aveforms such as: square,
sa tooth, triangle, pulse trains, spikes, as ell as distorted aveforms ith the
presence of harmonics. Harmonics may cause :
1) Overheated transformers, generators and motors to burn out faster than normal
2) Circuit breakers to trip prematurely
3) Fuses to blo
4) Neutrals to overheat due to the triplen harmonics present on the neutral
5) Bus bars and electrical panels to vibrate
Crest Factor
Crest Factor is the ratio of the Crest (instantaneous peak) value to the True RMS
value, and is commonly used to define the dynamic range of a True RMS DMM. A pure
sinusoidal aveform has a Crest Factor of 1.414. A badly distorted sinusoidal
aveform normally has a much higher Crest Factor.
OPERATION CAUTION
Before and after hazardous voltage measurements, test the voltage function on a
known source such as line voltage to determine proper meter functioning.

AutoV (LoZ) (Model 235 only)
AutoV automatically selects measurement function of DCV or ACV based, on their
input levels via the test leads. The input also provides a lo ramp-up impedance (LoZ)
to drain ghost voltages*.
●With no input, the meter displays “- - - -” hen 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, hichever
larger in peak magnitude.
Note:
*Ghost-voltage Buster: Ghost-voltages are unwanted stray signals coupled from
ad acent hard signals, which confuse common multimeter voltage measurements. The
AutoV mode provides low (ramp-up) input impedance (approx. 2.1kΩ at low voltage)
to 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.
*Only HOLD, EF Backlight push-button features are available in AutoV mode.

WARNING:
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 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. 2.4mA (1000V x 1.414 / 580kΩ) 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 loading for
such circuits.
ACV, DCV & VFD-ACV
Press the SELECT button momentarily to select the subject functions in sequence.
Last selection ill be saved as po er up default for repeat measurement convenience.
Note:
VFD-ACV and the associated Hz are equipped with digital low-pass filter (DSP), and
are capable of handling VFD (Variable Frequency Drives) signals for fundamental V &
Hz readings. It also improves ACV and Hz reading stability when being used in most
noisy electrical environments.

Line Frequency (Models 233 & 235 only)
Press the Hz push-button momentarily to toggle Hz function. It is only available to
Voltage and Current related ranges.
Input sensitivity varies automatically with the function range selected while activating
the Hz function. 6V function range has the highest and the 1000V range has the
lowest. When activated under DCV, ACV or VFD-ACV voltage function, the trigger
voltage range will be displayed right before starting the Hz readings. Press
momentarily the RANGE button can manually select another trigger voltage range (not
available to current ranges). It is recommended to first measure the signal voltage (or
current) level and activate Hz function in that range to get the most appropriate trigger
level. If the Hz reading becomes unstable, select lower sensitivity to avoid electrical
noise. If the reading shows zero, select higher sensitivity.

Resistance & BeepLitTM Continuity
Press the SELECT button momentarily to toggle the functions.
Last selection ill be saved as po er up default for repeat measurement convenience.
BeepLitTM Continuity function is having improved convenience for checking iring
connections and operation of s itches. A continuous beep tone together ith flashing
display backlight indicate a complete ire. Such audible and visible indications
improve continuity readabilities in noisy orking environments.
CAUTION
Using resistance and continuity function in a live circuit ill produce false results and
may damage the instrument. In many cases the suspected component must be
disconnected from the circuit to obtain an accurate reading

Capacitance (Models 235 & 233 only); Diode
Press the SELECT button momentarily to toggle the functions.
Last selection ill be saved as po er up default for repeat measurement convenience.
In Diode function, the normal for ard voltage drop (for ard biased) for a good silicon
diode is bet een 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 sho s OL if the diode is good. Any other readings indicate
the diode is resistive or shorted (defective).
CAUTION
Discharge capacitors before making any measurement. Large value capacitors should
be discharged through an appropriate resistance load.
Dave's Note: You can use the AutoV LowZ mode to discharge capacitors! (Can
be slow on big caps) You'll even get a handy voltage reading to know when it's
safely discharged.

ACmV & DCmV; Temperature oC & oF (Model 235 only)
Press the SELECT button momentarily to select the subject functions in sequence.
Last selection ill be saved as po er up default for repeat measurement convenience.
Note: Be sure to insert the banana plug type-K temperature bead probe Bkp60 ith
correct polarities. You can also use a plug adapter Bkb32 (Optional purchase)
ith banana pins to type-K socket to adapt other standard type-K mini plug
temperature probes.

A, mA and A Current
Press SELECT button momentarily to toggle bet een DC and AC.
Last selection ill be saved as po er up default for repeat measurement convenience.
Application notes for flame sensors:
DCA function is useful for HVAC/R flame sensor applications. The 0.1A resolution
can identify the minute current changes in flame detector applications. Flame signal
current check should indicate steady flame signal of at least 2A for a rectification
type, or 1.5A for an ultraviolet type (8A for self checking systems). If a flame signal
current ith inadequate strength or fluctuation beyond 10%, check the follo ing to
avoid the risk of un anted flame relay dropout :
For gas or oil flames (Minipeeper):
Lo supply voltage
Detector location
Defective detector iring
Dirty vie ing indo s
Faulty Minipeeper
For oil flames (Photocell):
Detector location & iring
Smoky flame or poorly adjusted air shutter

Faulty Photocell
Temperature over 165 oF (74 oC) at photocell
For gas flames (Flame Rod):
Ignition interference (A flame signal current difference ith the ignition both on and
off greater than 0.5A indicates the presence of ignition interference)
Insufficient ground (must be at least 4 times the detector area)
Flame lifting off burner head (ground), or not continuously in contact ith the flame
rod
Temperature in excess of 600 oF (316 oC) at the flame electrode insulator causing
short to ground.

Electric Field EF-Detection
Press the EF button momentarily to toggle EF-Detection feature. The meter displays
“EF-H” hen it is ready. If it is too sensitive for your applications, press (Level) button
momentarily toggles to lo er sensitivity “EF-L”. The detected Electric Field strength is
indicated as a series of bar-graph segments on the display plus variable beep tones.
●Non-Contact EF-Detection: An antenna is located along the top-left end of the
meter, hich detects electric field surrounding energized live conductors. It is ideal for
tracing live iring connections, locating iring breakages and to distinguish bet een
live and earth connections.
●Probe-Contact EF-Detection: For more precise indication of live ires, such as
distinguishing bet een Live and Ground connections, use direct contact testing ith
one single test-probe via the input terminal COM or V. The COM terminal (Black) has
the best sensitivity.

MAX/MIN/AVG Record mode
Press REC button momentarily to activate MAX/MIN/AVG recording mode. The LCD
“MAX MIN AVG” turn on. The meter beeps hen ne MAX (maximum) or MIN
(minimum) reading is updated. Press the button momentarily to read the MAX, MIN,
AVG readings in sequence. Press the button for 1 second or more to exit
MAX/MIN/AVG recording mode. Auto-ranging remains, and Auto-Po er-Off is disabled
automatically in this mode.
Backlighted LCD display
Press the SELECT button for 1 second or more to toggle the LCD backlight. The
backlight ill also be turned off automatically after 10 minutes to extend battery life.
Hold
The hold feature freezes the display for later vie . Press the HOLD button
momentarily to toggle the hold feature.
Relative Zero ( ) mode
Relative Zero allo s the user to offset the meter consecutive measurements ith
the displaying reading as the reference value. Practically all displaying readings can be
set as relative reference value including MAX/MIN/AVG feature readings. Press the
button for one second or more to toggle Relative Zero mode.

Manual or Auto-ranging
For most auto-ranging functions (LCD turns on by default), press the
RANGE button momentarily to select manual-ranging override. The meter ill remain
in the range it as in, the LCD turns off. Press the button momentarily again to
select the next range. Press and hold the button for 1 second or more to resume auto-
ranging.
Note: Manual-ranging feature is not available to Auto-V, Capacitance & Hz functions.
Beep-Jack™ Input Warning
The meter beeps as ell as displays “InEr” (insertion error) to arn the user against
possible damage to the meter due to improper connections to the A, mA, or A input
jacks hen another function, especially a voltage function, is selected.
Intelligent Auto-Power-Off (APO)
The Auto-Po er-off (APO) mode turns the meter off automatically to extend battery life
after approximately 32 minutes of no specified activities, here applicable:
1) Rotary s itch or push button operations
2) Significant measuring readings of above 8.5% of ranges
3) Non-OL readings for Resistance, Continuity or Diode function
4) Non-zero readings for Hz function
5) Electric field signal present for EF function
6) Significant movement indication as in Phase Rotation functions
In other ords, the meter ill intelligently avoid entering the APO mode hen it is
under normal measurements. To ake up the meter from APO, press the SELECT
button momentarily and release, or turn the rotary s itch OFF and then back on.
Al ays turn the rotary s itch to the OFF position hen the meter is not in use
APO is s itched OFF in REC MIN/MAX mode
5) MAINTENANCE
WARNING
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
ith open case. Install only the same type of fuse(s) or equivalent
Cleaning and Storage
Periodically ipe the case ith a damp cloth and mild detergent; do not use abrasives
or solvents. If the meter is not to be used for periods of longer than 60 days, remove
the battery and store it separately

Trouble Shooting
If the instrument looks to be buggered, check battery, fuses, leads, etc., and replace as
necessary. Double check operating procedure as described in this user’s manual
Battery:
1.5V AAA Size battery x 2
240 hours continuous use on
Alkaline cells
Fuse F1 for AmA current input:
0.4A/1000V DC/AC, IR
30kA FAST fuse or better;
Dimension: 6 x 32 mm
SIBA 70-172-40 FF400mA
Fuse F2 for A current input:
11A/1000V DC/AC, IR 20kA F
fuse or better; Dimension: 10 x
38mm
Bussman DMM-B-11A
Littlefuse FLU011
Battery and Fuse replacement:
Loosen the scre from the
access cover of the case bottom. Lift the access cover. Replace the batteries or
fuse(s). Re-fasten the scre .
Both fuses can be tested by inserting a probe into the A or mA/uA jack. If the IrEr
arning message and beep is not displayed, then the fuse on that input is blo n.
Dave's Note: Proper ceramic HRC (High Rupture Capacity) fuses are expensive,
but they are designed to fail safe and not explode. That makes you safer.
Don't be a tight arse and put cheap glass fuses in there instead! If you wanted
cheap you should have bought a cheap arse meter instead of this one.
Beware the fakes on ebay!
The 400mA will still be able to handle a 600mA (full scale) input for some time,
so no worries measuring full scale mA current. Fuses don't magically blow at
their rated current, it's a more complicated process than that!

GENERAL SPECIFICATION
Display: 3-5/6 digits 6,000 counts
Update Rate: 5 per second nominal
Operating Temperature: -10oC to 45oC
Relative Humidity: Maximum relative humidity 80% for temperature up to 31oC
decreasing linearly to 50% relative humidity at 45oC
Altitude: Operating belo 2000m
Storage Temperature: -20oC ~ 60oC, < 80% R.H. ( ith battery removed)
Temperature Coefficient: Nominal 0.15 x (specified accuracy)/ oC @ (-10oC ~ 18oC
or 28oC ~ 45oC), or other ise specified
Sensing: True RMS sensing
Ingress Protection: IP40
Pollution Degree: 2
Safety: Certified per IEC/UL/EN61010-1 Ed. 3.0, IEC/UL/EN61010-2-030 Ed. 1.0,
IEC/UL/EN61010-2-033 Ed. 1.0, IEC/UL/EN61010-031 Ed. 1.1 and the corresponding
CAN/CSA-C22.2 regulations to Measurement Categories:
CAT II 1000V, CAT III 600V and CAT IV 300V AC & DC
Transient Protection: 6.0kV (1.2/50s surge)
E.M.C. : Meets EN61326-1:2013
In an RF field of 3V/m:
Temperature function is not specified
Ohm function:
Total Accuracy = Specified Accuracy + 15 digits
Other functions:
Total Accuracy = Specified Accuracy
Performance above 3V/m is not specified
Overload Protection:
A & mA: 0.4A/1000V DC/AC rms, IR 30kA, F fuse or better
A: 11A/1000V DC/AC rms, IR 20kA, F fuse or better
V & AutoV: 1100V DC/AC rms
mV, Ohm & others: 1000V DC/AC rms
Low Battery: Belo approx. 2.5V
Power Supply: 1.5V AAA Size battery X 2
Power Consumption (typical): 3.2mA
APO Consumption (typical): 10A
APO Timing: Idle for 30 minutes
Battery Life: 240 hours nominal continuous use on Alkaline cells (Dave measured)
Dimension: 161*80*50mm L*W*H (With Holster)

Weight: Approx. 334 gm (With Holster)
Special Features: AutoV (LoZ) (Model 235 only); VFD; BeepLitTM Continuity; Auto-
ranging MAX/MIN/AVG Record; Backlighted LCD; Auto-ranging Relative Zero mode;
Display Hold; EF-Detection (NCV); BeepJack™ on AmA/A terminals
Accessories: Test lead pair; Batteries installed; User’s manual; BKP60 banana plug type-K
thermocouple (Model 235 only)
Optional Purchase Accessories: BKB32 banana plug to type-K socket plug adaptor
(Model 235 only); BMH-01 magnetic hanger; BMP-25x soft carrying pouch
Electrical Specification
Accuracy is given as (% of reading digits + number of digits) or other ise specified @
23oC  5oC
ACV & ACA accuracies are specified from 1 % to 100 % of range or other ise
specified. Maximum Crest Factor <2:1 at full scale & <4:1 at half scale, and ith
frequency components fall ithin the meter specified frequency band idth for non-
sinusoidal aveforms
AC Voltage
RANGE Accuracy
50Hz ~ 60Hz
6.000V 1), 60.00V, 600.0V, 1000V 0.7% + 3d
45Hz ~ 440Hz
6.000V 1), 60.00V, 600.0V, 1000V 2.0% + 3d
Input Impedance: 10M, 54pF nominal
1)<5d non-zero residue may appear hen backlight is on, hich ill not affect the
specified measuring range and accuracy
ACmV
RANGE Accuracy
10Hz ~ 500Hz
60.00mV 1) 2), 600.0mV 3) 1.0% + 3d
500Hz ~ 800Hz
60.00mV 1) 2), 600.0mV 3) 2.0% + 3d
Input Impedance: 10M, 54pF nominal
1)<5d non-zero residue may appear hen backlight is on, hich ill not affect the
specified measuring range and accuracy
2)Signal peak absolute values, including DC bias, less than 130mVpeak
3)Signal peak absolute values, including DC bias, less than 1300mVpeak