DMM 939
3¾ Digit LCD Autoranging Multimeter
This module is a complete multimeter in a panel instrument. It is especially useful in portable equipment and has 12 ranges:
D.C. - 400mV, 4V, 40V and 400V (Maximum IP ±375V)
D.C. - 4000µA, 40mA, 400mA, 4A,
Resistance - 4kΩ, 40kΩ, 400kΩ and 4MΩ.
15mm (0.6“)Digit Height
Digital Hold
-
M
+
k
Autoranging
uA
mAV
Low Battery Indication
LED Backlighting
D.C. Supply Isolator
Continuity Beeper Output
Stock Number
Standard Meter
METER PROTECTION
Accuracy
D.C. volts 400V
D.C. volts all other
Ohms 4 kilohms, 400 kilohms
Ohms 40 kilohms, 4 megohms
D.C. current adjusted
Linearity (best straight line)
Rollover error
Operating temperature range
Supply voltage (Vp+ to Vp-)
Supply current (excluding backlight)
Continuity detect low ohm range
Converter isolation (D.C.)
Backlight current (5V nom.)
RECALIBRATING THE METER
Power the meter with its typical working voltage and make
connections as follows:
- Connect Pin 8 to Pin 1.
- Apply -3.700 volts D.C. between V/Ω (Pin 3) and COM (Pin 4).
- Adjust R4 until meter displays -3.700V.
LOW POWER OPERATION
If ultra low power operation is required, then an isolated
supply (battery) can be applied across V+ and V- to give this
mode of operation.
Note - Ensure that the supply does not exceed 11 volts.
Low Power Operation
Supply voltage (V+ to V-)
Supply current
Low battery threshold
Min.
7
6.5
Typ.
9
1.5
7
Max.
11
2.4
7.5
DMM 939
Specification
The meter should be protected against accidental application
of high voltages on ohms and current ranges by a fast-blow
5A fuse.
Min. Typ. Max.
±1
±0.5
-1
±2
±0.3
±0.75
±4
0
5
5
9
7
1.5
50
+1
50
18
13
40
90
Unit
% Rdg ± 1 count
% Rdg ± 1 count
% Rdg ± 8 counts
% Rdg ± 9 counts
% Rdg ± 2 counts
count
counts
°C
V
mA
kilohms
V
mA
CONNECTOR SOURCING GUIDE
Unit
V
mA
V
METHOD
Cable Mounting IDC Supplied With Product
DIMENSIONS All dimensions in mm (inches)
24.0 (0.94)
40.5 (1.59)
POL/AC
mA/µA
K/m
Ω/A
BAT/V
44.0 (1.73)
HΩ-DC/
LΩ-~
Panel cut-out 72 x 40 (2.83 x 1.57)
Maximum panel thickness 3mm (0.12).
Display in "Overload"
1
19
20
RES
b c
1
2
mA
I
REAR
VIEW
1.0 (0.04)
2.0 (0.08)
6.5 (0.26)
11.5 (0.45)
10.0 (0.39)
OVERLOAD
When the meter displays
"OL" this indicates that the
meter inputs have been
taken beyond their working
range.
a
72.5 (2.85)
51.0 (2.01)
1
2
VCOM
mA/µA
76.0 (2.99)
Ω
BEEP
LED+
Vp-
19
20
Ø3.0
(0.12)
a.
b.
c.
d.
e.
51 (2.01)
REAR
VIEW
24.5 (0.96)
24.0 (0.94)
e
V+
V/Ω
mA
V/Ω/A
mA
HOLD
LEDVp+
39.0 (1.54)
d
Ø5.7
(0.22)
24 (0.94)
61.5 (2.42)
51.0 (2.01)
ON BOARD SOLDER LINKS
LASCAR ELECTRONICS LTD.
MODULE HOUSE, WHITEPARISH,
WILTSHIRE SP5 2SJ UK
TEL: +44 (0)1794 884567 FAX: +44 (0)1794 884616
E-mail: sales@lascar.co.uk
LASCAR ELECTRONICS INC.
LASCAR ELECTRONICS (HK) LIMITED
3750 West 26th Street,
Erie, PA 16506 USA
TEL: +1 (814) 835 0621 FAX: +1 (814) 838 8141
E-mail: us-sales@lascarelectronics.com
FLAT C, 5/FL., LUCKY FTY. bldg., 63-65 HUNG TO ROAD
KWUN TONG, KOWLOON, HONG KONG
TEL: +852 2797 3219 FAX: +852 2343 6187
E-mail: b4lascar@samsongroup.com.hk
PIN FUNCTIONS
1.
2.
3.
4.
V+
VV/Ω
COM
Positive power supply connection.Not isolated.
Pins 1 and 2 are used for mode selection and low power operation.
Negative power supply connection.
Positive Volts measuring input. Connect to Ω (Pin 10) to measure resistance.
Ground for analogue section of the A/D converter, it is held actively at 2.9V (typ.) below V+. COM must not be allowed to sink
excessive current (>100µA) by connecting it directly to a higher voltage.
Positive milli-Amperes measuring input.
Tri-State Input Connections
Tri-state input, connect to V+ to display 'mA' annunciator.
Pin No.
V+
OPEN or COM
VConnect to COM to display 'µA' annunciator. Note - mA/µA
6
mA
mA
Do not connect to Vannunciators will not be displayed unless Pin 7 is connected to V-.
7
V
A
Ω
Tri-state input, connect to COM to operate voltage range and to
8
HΩ-DC
LΩ
Do not connect to Vdisplay 'V' annunciator. Connect to V+ to operate Resistance range
11
HOLD
AUTO
Do not connect to Vand to display relevant 'Ω' annunciator or connect to V- to display
either mA or µA, selection between each of these annunicators is determined by Pin 6.
Tri-state input, connect to V+ to select High Ohms and D.C. range input. Connect to COM for Low Ohms.
All the ranges will show the appropriate annunciator, MΩ, kΩ or ~ symbol.
Positive micro-Amperes measuring input.
Ohms measuring input. Connect to Pin 3 when measuring resistance.
Tri-state input, connect to V+ to hold display reading.
The continuity beeper output is designed to drive a piezo-electric transducer at approximately 2KHz with a voltage swing of V+
to V-. Note - The beeper output off state is at the V+ rail.
Negative supply to LEDs for backlighting.
LED+ to LED- supply voltage of 5V.
Positive supply to LEDs for backlighting.
Positive isolated power supply connection.
It is recommended that the meter is powered using these pins.
Negative isolated power supply connection.
No pins fitted.
5. mA
6. mA/µA
7. V/Ω/A
8. HΩ-DC/
LΩ
9. µA
10. Ω
11. HOLD
12. BEEP
13. LED14. LED+
15. Vp+
16. Vp17-20
VARIOUS OPERATING MODES
1
11
15 Vp+ V+
HOLD
16
VpHΩ-DC/ 8
3
V
LΩ
7
10
V/Ω/A
Ω
12
BEEP
4 COM
SUPPLY
(5-18V)
Resistance to be
placed across
these terminals
for measurement
S2
N.C.
S3
N.C.
Piezo-electric
Transducer
+
Input Current
to be measured
-
Autoranging Resistance Meter
Ranges: Low Ohm - 4kΩ, 40kΩ
High Ohm - 400kΩ, 4MΩ
15
SUPPLY
(5-18V)
16
V/Ω
3
10
S4A
CURRENT
S5A
COM
*RS
0.1Ω
5A Quick
Blow Fuse
Vp+
Vp-
1
V+
HOLD
BEEP
9
µA
5
mA
4
COM
11
HΩ-D.C./ 8
LΩ
V
Ω
V/Ω/A
mA/µA
V-
S5A
Rs
0.1Ω
*
5A Quick
Blow Fuse
5A Quick
Blow Fuse
S1
8
1
Vp+ V+
HΩ-DC/ 8
16
LΩ
Vp11
9
HOLD
µA
15
SUPPLY
(5-18V)
S2
S3
12
7
6
Piezoelectric
Transducer
+
5
4
mA
mA/µA 6
COM
V2
V/Ω/A
15
SUPPLY
(5-18V)
S2
16
3
S5B
Input Voltage
to be measured
7
Autoranging D.C. Current Meter
Ranges: µA - 4000µA, 40mA
mA - 400mA, 4000mA
*Note - Rs is the current sensing resistor
and must be capable of handling as a
minimum the full scale current of 4 amps.
To allow for overload conditions, it is
recommended that a 6W, 0.5% resistor is
fitted. It must be fitted when EITHER of
the current ranges are being used.
4
8
1
Vp+ V+
Vp-
HOLD
11
S2
V
V/Ω/A 7
COM
Autoranging Volt Meter
S4B
S5B
2
Autoranging Voltage, Current and Resistance Meter
*See note on Current Meter diagram.
SWITCHES
S1. Switch 1 is an on/off switch.
S2. Switch 2 is used to hold the display reading.
S3. In Voltage mode, switch 3 is used to select D.C. measurement and the ~ symbol.
In Resistance mode, this switch is used to select either high or low ohms ranges.
S4. Switch 4 selects either the Voltage, Current or Resistance ranges.
S5. Switch 5 selects between Current ranges.
HEALTH AND SAFETY
1.
2.
3.
4.
When the DMM is used for current or resistance measurements, an external fuse MUST be fitted.
When measuring voltages in excess of 60V peak, the system within which the DMM is incorporated, should conform to relevant sections of
IEC 1010 (Safety Requirements for Electrical Equipment for Measuring, Control and Laboratory Use).
If this product is to be used for measuring mains supply voltages, external transient protection should be adopted.
To comply with the Low Voltage Directive (LVD 93/68/EEC), input voltages to the module’s pins must not exceed 60Vdc, then fit scaling resistors
externally to the module. The user must ensure that the incorporation of the DPM into the user’s equipment conforms to the relevant sections of
BS EN 61010 (Safety Requirements for Electrical Equipment for Measuring, Control and Laboratory Use).
Specifications liable to change without prior warning
DMM 939
Issue 3
August/1997
M.C.
Applies to DMM 939/5