DATA PRECISION 1350 User manual

62-5008
Instruction Manual
M0DEL1350
3-1/2 DIGIT
QENERALPURPOSEDIGITALMULTIMETER
kpHoAIA PRECISION
...years ahead

62-5008 MODEL 1350
FIRST EDITION
November, 1977
Copyright 1977. Data Precision Corporation
Printed in U.S.A.
PROPRIETARY NOTICE
The information contained in this publication is
derived in part from proprietary and patent data
of the Data Precision Corporation.This informa
tion has been prepared for the express purpose of
assisting operating and maintenance personnel in
the efficient use of the instrument described
herein, and publication of this information does
not convey any rights to reproduce it or to use it
for any purpose other than in connection with the
installation, operation, and maintenance of the
equipment described herein.

62-5008 MODEL 1350
CONTENTS
1. INTRODUCTION & SPECIFICATIONS
1.1 General
1.2
Book Plan
1.3
Specifications
1.3.1 DC Volts
1.3.2 AC Volts
1.3.3 Resistance
1.3.4
DC Current
1.3.5 AC Current
1.3.6
Functional Characteristics
1.3.7
Power Supply
1.3.8
Environment
1.3.9
Mechanical Configuration
1.4 Accessories
2. OPERATION
2.1 General
2.2 Unpacking & Repacking
2.3 Front Panel Controls & Indicators
2.4 Rear Panel Features
2.5 Signal Connections
2.6 Making A Measurement
2.7 Application Notes
2.7.1 General
2.7.2 Avoiding Ground Loops (Grounded Measurements)
2.7.3 Making "Floating" Measurements
2.7.4 Making High Resistance Measurements
2.7.5 Making Very Low Voltage Measurements
3. CALIBRATION
3.1 General
3.2 Calibration Adjustments
3.3 Calibration Procedure
©
Copyright 1977. Data Precision Corporation. All rights reserved.

62-5008 MODEL 1350
4. PRINCIPLES OF OPERATION
4.1 General
4.2 System Block Diagram
4.3 System Timing
4.4 Signal Conditioning Details
4.4.1 DCV Signal Conditioning
4.4.2 DCmA Signal Conditioning
4.4.3 AC/DC Converter Signal Conditioning
4.4.4 Resistance Signal Conditioning
4.5 A/D Converter Details
4.5.1 Analog Section
4.5.2 Digital Section
4.6 Display
4.7 Power Supply
4.8 Reference Supply
5. MAINTENANCE
5.1 General
5.2 Trouble Shooting Strategy
5.3 Access to Model 1350 DMM Assemblies & Test Points
5.4 Open-Case Trouble Shooting Procedures
5.5 Power Supply Test
5.6 Reference Power Supply Test
5.7 AC/DC Converter Tests
5.8 A/D Converter Tests
5.9 Display Tests
5.10 Replaceable Parts
6. PARTS LISTS
Reference Schematic
©
Copyright 1977. Data Precision Corporatton. Afl rights reserved.
Ill

62-5008
MODEL 1350
Frontispiece. Model 1350 DMM 3/4 Digit Digital Multimeter
©
Copyright 1977. Data Precision Corporation. AH rights reserved.

62-5008 MODEL 1350
Chapter 1
INTRODUCTION & SPECIFICATIONS
1.1 GENERAL
Data Precision Model 1350 Digital Multimeter (DMM) is a 3V2 digit, gen
eral purpose, rugged and reliable bench-top performer. Its light weight
assembly, mounted in a high impact-proof plastic case with integral
carrying handle tilt stand makes it an ideal work horse tor shop, industry,
and school applications.
The Model 1350 provides 27 Measuring Function/Range Capabilities,
including DCV, ACV, DCmA, ACmA, and Hi or Lo Ktl, with resolutions of
100 microvolts, 100 nanoamperes, and 100 milliohms tor voltage, cur
rent, and resistance measurements, respectively. Input circuitry is pro
tected against application of voltages up to 1200VDC, up to 1000V
RMS, and currents up to 2 amperes, while also being protected against
6000-V spikes applied tor up to 500 nanoseconds. High common mode
rejection of 140dB at dc and over 120dB at 50 and 60Hz enhance the
applications in harsh industrial environments.
The display of 0.43" (1.1 cm) LED digits provide excellent visibility even
in high level ambient light. They are mounted immediately behind a front
panel optical filter tor wide-angle, parallax-tree readings. Polarity is dis
played automatically tor dc measurements, and the decimal point is po
sitioned automatically in all measurements so that readings are made
directly in units indicated by the range scale selection. The display digits
are blanked tor out-ot-range signals, leaving the decimal point, MSD,
and polarity sign (it dc measurement) lighted to indicate an operable
multimeter and to avoid making invalid readings of out-ot-range signals.
Model 1350 DMM is factory-calibrated and performance warranted tor
one year. Recalibration, when necessary, is accomplished with only two
simple, non-interactive adjustments.
^Copyrigrit 1977. Data Precision Corporation. Ail rights reseri/ed. ^ ^

62-5008
MODEL 1350
1.2 BOOK PLAN
Information in ttiis manual is organized so that operators and system
users may locate applicable data and instructions (through Chapter 3)
without having to wade through technical detail necessary for mainte
nance and repair. Information in Chapter 4 and Chapter 5 essentially
support the technical requirements for maintenance, trouble-shooting
and repair activities.
1.3 SPECIFICATIONS
1.3.1 DC VOLTS
Nominal Range
Overrange
Resolution
±100.0 mVDC
±199.9
100/xV
±1.000 VDC
±1.999
ImV
±10.00 VDC
±19.99
lOmV
±100.0 VDC
±199.9
lOOmV
±1000. VDC
±1200.
IV
Input Impedance:
lOMfi, all ranges
Maximum Voltage:
±1200VDC, all ranges
±6000V for .5/xS, all ranges
Accuracy (1 year, 23°C, ±5°C):
±0.1% input ±1 l.s.d.
Temperature Coefficient
(0°C to 40°C, all ranges):
±0.01% input/°C ± .01% range/°C
Common Mode Rejection Ratios (minimum)
with lOOOn source impedance imbalance:
140dB at DC. >120dB at 50 and 60Hz
Normal Mode Rejection Ratio:
SOdB at 50Hz and 60Hz
Common Mode Voltage:
500VDC (or peak AC) maximum when connected
to AC power line.
1-2
©
Copyright 1977. Data Precision Corporation. All rights reserved.

62-5008
MODEL 1350
1.3.2 AC VOLTS
Nominal Range Overrange
Resolution
lOO.OmVAC 199.9
100/aV
1.000 VAC
1.999
ImV
10.00 VAC 19.99 lOmV
100.0 VAC 199.9 lOOmV
1000. VAC
1000. IV
Input Impedance:
10Mn in parallel with 10Opf or less
Sensing and Calibration:
Average Sensing, caiibrated in RMS of sinewave
Accuracy (1 year, 23°C ±5°C):
Range 30-50HZ
50-500HZ
lOOmV
± 1 % ± 5 isd ±.5% ±2 Isd
1 V
±1% ±5 Isd
±.5% ±2 Isd
10 V
±1% ±5 Isd
±.5% ±2 Isd
100 V
±1% ±5 Isd
±.5% ±2 Isd
1000 V
±1% ±5 Isd
±.75%±2 Isd
500-1 GODHz
1000-2000HZ
2kHz-10kHz
±1% ±2 Isd
±1% ±2 Isd
±1% ±2 Isd
±1% ±2 Isd
±1.5% ±2 Isd
±2% ±2 Isd
±2% ±2 Isd
±2% ±2 Isd
±4% ±2 Isd
±3dB ±10 Isd
±3dB ±10 Isd
±3dB ±10 isd
Temperature Coefficient
(0°C to 40°C, all ranges):
30Hz to 500Hz: ±.02% input/°C ±.02% range/°C
500Hz to 2kHz: ±.05% input/°C ±.05% range
Maximum Input Voltage
(sinewave RMS):
30Hz to 2kHz: 1000V
''Copyright 1977. Data Precision Corporation. AM rights reserved.
1-3

62-5008
MODEL 1350
1.3.3 RESISTANCE
Nominal Range
Overrange
Resolution
- il
199.9 a
looma
i.oookn
1.999ka
1 a
lo.ookn
19.99ka
10 a
loo.okn
199.9ka
100 a
looo.kn
1999.ka
ika
lo.ooMn
19.99Ma
lOka
Accuracy (1 year, 23°C ±5°C):
HIV
LoV
looa:
Ika to lOOOka:
lOMa:
±.2% ±2 Isd + lOOma
±.1% ±1 Isd
± .3% ± 1 Isd
±.2% ±2 Isd
± 1% ±2 Isd
Maximum Open Cir
cuit Voltage:
Temperature Coefficient
(0°C to 40°C):
lOO.Onto lOOO.kfi:
lOMil:
Maximum Test Current:
1.4mA
Maximum Input Voltage:
500V RMS AC or DC
Settling Time:
lOO.Onto lOOOkn:
lOMfl:
2.8V
±.01% inputyC
± .02% input/°C
SOOmV
.01% range/°C
.02% range/°C
2 seconds
5 seconds
1.3.4 DC CURRENT
Nominal Range
Overrange
Resolution
±100.0/mA ±199.9,xA
O.VA
± 1.000mA
± 1.999mA
1 fiA
± 10.00mA
± 19.99mA
10/xA
± 100.0mA
± 199.9mA
lOO^A
±1000 mA
± 1999 mA
1mA
1-4
©
Copyright 1977. Data Precision Corporation. All rights reserved.

62-5008
MODEL 1350
Maximum Current:
Series 2A fuse (250V)
Nominal Full Scale Voltage
across Shunts:
100mV
Accuracy (1 year, 23°C ±5°C):
±0.5% input ±1 l.s.d.
Temperature Coefficient
(O-C to 40°C):
± .02% input/°C ± .01 % range/°C
1.3.5 AC CURRENT
Nominal Range
Overrange Resolution
100.0/liA
199.9iaA O.VA
1.000mA 1.999mA
1 /xA
10.00mA
19.99mA
10/xA
100.0mA
199.9mA
lOOjuA
1000 mA
1999 mA 1mA
Maximum Current:
Series 2A fuse (250V)
Nominal Full Scale Voltage
across Shunts:
lOOmV RMS
Accuracy (1 year, 23°C ±5°C):
30Hz to 50Hz:
50Hz to 500Hz:
500Hz to 2kHz:
Temperature Coefficient:
30Hz to 2kHz:
±1.5% input ±5 l.s.d.
±.75% input ±2 l.s.d.
±1.5% input ±5 l.s.d.
±.03% input/°C ±.02% range/°C
1.3.6 FUNCTIONAL CHARACTERISTICS
Reading Rate:
2.5 readings/second
Polarity:
Autopolarity
Overload Protection:
Blanking of all digits leaving sign and decimal point illuminated.
Overrange:
100%, except on 1000V ranges
^Copyright 1977. Data Precision Corporatton. All rights reserved.
1-5

62-5008 MODEL 1350
1.3.7 POWER SUPPLY
100-130V, 47-400HZ, 5 Watts
1.3.8 ENVIRONMENT
Temperature Range:
Operating, 0°C to 40°C
Storage, -25°G to +50°C
Humidity:
80% RH maximum, 0°C to 40°C
1.3.9 MECHANICAL CONFIGURATION
Package:
New Plastic Case
8V2" W X 9%" D X 2W H (Including Handles)
Weight 3V4lb(1.5kg)
Display:
3V2 Digit, .43" (1.1 cm) LED
Switches:
Eleven (11) Pushbuttons in Three (3) Groups
1. On/Off
2. Mode-V, kn, mA, AC/DC — Hin/LoD
3. Range —.1,1, 10, 100, 1000, lOMft
Connectors:
Four: V, kft High
mA High (Front Panel Banana)
Input Low
Earth ground (Rear Panel Universal)
Fuses:
Rear Panel Line Fuse
Internal Current Shunt Protection Fuse
Power Input:
3 wire Line Cord.
1-8
©Copyright 1977. Data Precision Corporation. All right

62-5008 MODEL 1350
1.4 ACCESSORIES (OPTIONS)
The following optional accessories are avaiiabie to extend the Modei
1350 DMM performance; they may be obtained from Data Precision
distributors.
Data Precision
Description Model No.
*Test Leads T5
Rack Mount (L, R, or Dual) L75, R75, D75
High Voltage Probe (to 40KV) V41A
Current Probe (to 150 Amp.) IP151
E-Z Hooks (Probe attachments) E-Z
Deluxe Test Leads Kit TX
*One set included at no charge as part of basic ordering configuration.
1 1-7
-'Copyright 1977. Data Pracision Corporation. All rights rasarvad.

62-5008 MODEL 1350
Chapter 2
OPERATION
NOTE:
Read this chapter carefully before attempting to use your
Model 1350 DMM. Retain these Instructions. Observe all
WARNINGS and CAUTIONS.
2.1 GENERAL
a. Chapter 2 contains detailed Instructions for connecting and operating
the Model 1350 DMM, Including safety precautions to prevent damage
to personnel or equipment. Refer to the specifications In Paragraph 1.3
to obtain the tolerance with which displayed measurements may be
Interpreted.
b. SAFETY MARKINGS. The front panel Incorporates two standard
operator warnings. The significance of each Is:
A
Located among the Input terminals.
This advises the operator to refer to the Instruction manual before using
these temlnals.
/
©
Located to the right of terminal "V, Kil".
This warns the operator that there may be dangerously high voltage at
this location, or that there Is a voltage limitation to be considered when
using this terminals.
The rear panel mounts a standard grounding lug, electrically connected
to the "ground" terminal of the 3-wlre line cord receptacle In the rear
panel.
2.2 UNPACKING & REPACKING
a. Figure 2-1 identifies the components of the packaging configuration
for Model 1350 DMM. As shown In that Illustration, the multimeter Is
placed In a waterproof plastic wrapper, securely fitted between molded-
foam shock Isolators, and placed with the documentation In Its shipping
carton. When unpacked, you should find:
Copyright 1977. Data Precision Corporation. All rights reserved.
2-1

62-5008
MODEL 1350
FOAM LINER
,MODEL 1350 DMM
DOCUMENTATIO
PLASTIC
CONTAINER
PROIE SET. CLIPS. SPARE FUSES.ETC.
Figure 2-1. Model 1350 DMM Packaging Configuration
(1)Model 1350 DMM
(2) Test Probe Assembly & Alligator Clips
(3) Certificate of Conformance
(4) Warranty Card
(5) Factory Test Data Sheet
(7) Spare 2A 250V 3AG Fuse, F301
(8) Spare V4A 250V 3AG Fuse, F302
b. Carefully examine these articles, noting especially the matching serial
numbers of the instrument and the test data. Inspect the packing case
and the instrument for any signs of damage during shipment and report
immediately to the carrier. Fill out and return the warranty card to regis
ter your instrument and to establish your warranty service interval.
c. Accessories, such as spare leads or high voltage probes, may have
been ordered. These will be shipped in their own containers.
d. Retain the packing material for reshipment. When shipping Model
1350 DMM, place the instrument in its protective carrying case, includ
ing test probes and line cord. Use foam liners and pack in original ship
ping carton, if available.
2.3 FRONT PANEL CONTROLS & INDICATORS
Figure 2-2 and Table 2-1 identify and describe operating features at the
front panel of the standard Model 1350 Digital Multimeter.
2-2
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Copyright 1977. Data Praclston Corporation. AM right
ad.

62-6008 MODEL 1350
Table 2-1
FRONT PANEL OPERATING FEATURES (Figure 2-2)
Fig.
Ref.
Name/Description Function
1. Display (0.43" LED) 3 full decades, MSD "1", polarity (+,-),
and decimal point. Direct reading in units
determined by function & range selected.
2.
V, Kn — COM
(J400-J402)
Two banana plug connectors (tiigh and
return), for voltage and resistance inputs.
COM may be up to ± 500 VDC from eartfi
ground: voltages may be up to 1000 VDC
or VRMS. Displayed polarity is ttiat of
J400 with respect to J402.
3. mA — COM
(J401-J402)
Two banana plug connectors (source and
return) for current input signals, up to 2
amperes.
4. Range Selector
6 interlocked pushbuttons, with panel
markings identifying the magnitude and
unit of the selected range scale. Range
selection automatically positions the deci
mal point.
5. Conditioning
Mode Selection
Push-push switch. Determines the type
of signal conditioning for the selected
function of item 6. IN selects ac for volt
age, current, and LO voltage for resis
tance. OUT selects dc for voltage, cur
rent, and HI voltage for resistance.
6.
Function Selectors
3 interlocked pushbuttons, with panel
markings identifying the measuring func
tion (V, kn, mA) selected by each.
7. POWER ON-OFF Push-push switch. Applies and removes
line power to meter circuitry.
''Copyright 1977. Data Pracision Corporation. All rights resarvad.
2-3

62-5008 MODEL 1350
v-kn
100 noo mk
TA PRECI
Figure 2-2. Model 1350 DMM Front Panel Features
2-4 Figure 2-3. Model 1350 DMM Rear Panel Features
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Copyright 1977. Data Precision Corporation. All rights reserved.
L

62-5008
MODEL 1350
2.4 REAR PANEL FEATURES
Figure 2-3 and Table 2-2 identify and describe features at the rear panel
of Model 1350 Digital Multimeter.
Table 2-2
REAR PANEL OPERATING FEATURES (Fig. 2-3)
Fig.
Name/Description
Function
1. Retaining Screws
2 Screws fastening top case cover to rear
panel.
2. Fuse (F300)
VaA 250V Fast Blow 3AG line fuse.
3. Line Cord
3-conductor ac line cord.
4.
Ground (J300)
Binding post for line and chassis ground.
5.
Fuse (F301) 2A, 250V, Fast Blow 3AG fuse in series
with current measurement input.
6. Retaining Screws
2 Screws fastening bottom case cover to
rear panel.
2.5 SIGNAL CONNECTIONS
a. A pair of test leads is furnished as a standard accessory with each
Model 1350 Digital Multimeter. A banana plug connector at one end
mates with the Model 1350 Digital Multimeter front panel input connec
tor, while the probe end of each lead may be configured for spade lug
contact, or mini-E-Z hook using the deluxe test lead accesory kit, TX.
Alligator clip adaptors are furnished at no additional charge with each
standard test lead set.
b. When measuring with a Model 1350 Digital Multimeter, it is important
to minimize ground loops that may introduce noise into the input circuit.
(See applications data, paragraph 2.7.)
c. Input terminals (Figure 2-2, Item 2) are used as the front panel con
nector pair to measure voltages up to 1000 volts, and resistances up to
20 Megohms.
'^Copyright 1977. Data Pracision Corporation. All righ
ad.
2-5

62-5008 MODEL 1350
d. Input terminals (Figure 2-2, Item 3) are used as the front panel con
nector pair to measure currents up to 2 amperes.
CAUTION
Before connecting the Model 1350 DMM to the unit under
test, be sure that the values do not exceed the limits indica
ted on the front panel.
2.6 MAKING A MEASUREMENT
To make a measurement with Model 1350 DMM:
a. Turn power ON.
b. Operate the appropriate one of three pushbuttons for the measure
ment parameter (V, Kft, mA).
0. Select the appropriate position (In or Out) for the mode of signal con
ditioning (AC or DC, Hi or Lo).
d. Connect test probes to the circuit and to the meter front panel, using
designated connector pair for the parameter to be measured (Voltage/
Resistance, or Current).
e. Read value on the display directly in terms of the units of selected
measuring function. Polarity (for dc measurements) is displayed auto
matically, indicating the relative value of the HI input with respect to the
COM terminal input. The decimal point is positioned automatically for
the selected range. If the display indicates an out-of-range signal (digits
are blanked), shift to the next higher range, if possible. If out-of-range
for the highest range scale, the signal exceeds safe limits, unless
measuring resistance^and should be disconnnected immediately! Use
caution!
If value displayed is less than 190 counts (and lowest range scale has
not been selected), then shift to next lower range scale to obtain im
proved resolution of measurement. For example;
If display is-1-1.12 on Range 10,
It may become -i-1.126 on Range 1 (or some other least significant
digit).
2-6
^Copyright 1977. Data Preciiion Corporation. All rights retarvad.

62-5008
MODEL 1350
f. Table 2-3 summarizes the pushbutton selections for measurements of
the different parameters, and the modes of signal conditioning for each.
g. Table 2-4 illustrates some typical display values and their
interpretations.
Table 2-3
FRONT PANEL MEASUREMENT/SWITCH CONFIGURATIONS
TO
MEASURE
SELECT
OPERATE
V
KO
mA ■H OUT
i| IN
DCV
•
•
ACV
•
DCmA
f •
ACmA
•
KS2(HI)
f •
KfifLO)
•
•
2.7 APPLICATION NOTES
2.7.1 General
Optimum performance is obtained from your Model 1350 DMM by ofc)-
serving a number of precautions in establishing the test measurement
conditions. The few hints included in these paragraphs are only indica
tive of the types of measuring environment problems which may influ
ence the meter performance. It is suggested that the user record his
own application aids as he determines them.
2.7.2 Avoiding Ground Loops (Grounded Measurements)
A potential difference may exist between the "ground" of the power
source and the "ground" of the measured circuit. (See Figure 2-4.) This
difference of ground potentials may set up ground-loop currents and af
fect the measured values although the instrument will reduce their ef
fects significantly (CMRR = 120dB, NMRR = 60db).
■^Copyright 1977. Data Pracision Corporation. Alt righ
•d.
2-7

62-5008
MODEL 1350
<5>
IMODEL
1350
COMMON MODE VOLTAGE
SIGNAL SOURCE
Figure 2-4. Ground Loops in Grounded Measurements
MODEL
2-8
Figure 2-5. Noise Coupling in AC Measurements
©
Copyright 1977. Data Precision Corporation. All rights reserved.