4
The LED Display
The high-contrast 4-1/2 digit LED display is easily read from across the room. It can register from 0000 to
19999 counts. For ease of discussion, the 19999 will be rounded to 20000 in the remainder of this text.
For example, we will refer to the 2V range, not the 1.9999V range. In all linear functions, the decimal point
position is determined by the range selected. Polarity of the input signal is indicated by a ‘ – ‘ sign at the
center of the left side of the LED. The + sign is disabled in the AC V, AC mA, and k
Ω
measurement
functions. The ‘ – ‘ sign may appear in any measurement function, but is normally not meaningful when
making AC V, AC mA, and k
Ω
measurements. You will only get this indication of an energized circuit if
the power in the circuit is negative with respect to the COMMON input terminal. If the power in the circuit
is positive with respect to the COMMON input terminal, an erroneous resistance will be displayed. If there
is any doubt about whether there is energy remaining in the circuit you are reading, read the resistance,
then reverse the test lead positions. If the minus sign is displayed in either case, the remaining energy
must be removed from the circuit before correct resistance readings can be made. If you apply an input
signal that exceeds the limits of the range selected, the LED display will flash. All decimal point positions
appear in the display to indicate certain illegal combinations of front panel switch settings. For example, if
you select the DCV function and the 20M range, all four decimal points will appear on the display.
POWER Switch
The green POWER switch is located in the right corner of the DMM front panel. To turn the meter ON,
push the POWER button in. To turn the meter OFF, push the POWER button in.
CAT I
1000V
DC 1200V
AC 1000V
500V
MAX
200uA 2mA 20mA 200mA 2A 20A
200mV 2 20 200
200 2k
G
20k 200k 2M 20M
1000VAC
1200VDC
TRUE
RMS
20 A
20A MAX
AC
DC
mA-2A
2A MAX
POWER
BDM40
COM
V
Ω
1
3
2
6
5
4
W
WARNING
T
TO AVOID ELECTRICAL SHOCK
DISCONNECT TEST LEADS AND
POWER CORD BEFORE REMOVING
COVER.
DO NOT OPERATE INSTRUMENT
WITH COVER REMOVED.
TO PREVENT FIRE, REPLACE FUSE
WITH SAME AND RATING
MADE IN TAIWAN
SERIAL NO.
15 VA MAX
50 Hz / 60 Hz
B
117 VAC 105 VAC - 128 VAC
AC MAINS SELECTOR
117 V 230 V
117 VAC F 0.125 A / 250V
MAINS SUPPLY FUSE
W
230 VAC F 0.08 A / 250 V
230 VAC 210 VAC - 257 VAC
P
8
9
7
Figure 1: BDM40 Controls
1. Voltage, Ohms and Diode inputs.
2. Current (mA to 2A) and 20A inputs.
3. Reading display 0000 to 19999.
4. Power button (green).
5. Range selection switches. The pushbuttons
are interlocked with the other ranges.
6. Function selection switches.
The
pushbuttons are interlocked with the other two
white function
selection switches A and
Ω
.
7. Line Power connector.
8. Line Voltage selector switch.
9. Line
Power
Fuse.
