Omega Products 872A Installation Manual

®

User’s Guide

http://www.omega.com

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Only model 871A has
CE certification

871A and 872A

Digital Thermometers

omega.com

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OMEGA

®

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http://www.omega.com [e-mail]

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Canada: 976 Bergar

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For immediate technical or application assistance:

USA and Canada: Sales Service: 1-800-826-6342 / 1-800-TC-OMEGA

Customer Service: 1-800-622-2378 / 1-800-622-BEST
Engineering Service: 1-800-872-9436 / 1-800-USA-WHEN

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TELEX: 996404 EASYLINK: 62968934 CABLE: OMEGA

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Servicing Europe:

Benelux: Postbus 8034, 1180 LA Amstelveen, The Netherlands

Czech Republic: Ostravska 767, 733 01 Karvina

France: 9, rue Denis Papin, 78190 Trappes

Germany/Austria: Daimlerstrasse 26, D-75392 Deckenpfronn, Germany

United Kingdom: 25 Swannington Road, P.O. Box 7, Omega Drive,

ISO 9002 Certified Broughton Astley, Leicestershire, Irlam, Manchester,

It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that apply. OMEGA is
constantly pursuing certification of its products to the European New Approach Directives. OMEGA will add the
CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct but OMEGA Engineering, Inc. accepts no liability for any
errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient connected applications.

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TABLE OF CONTENTS

MODEL 871A AND MODEL 872A

DIGITAL THERMOMETERS

SECTION PAGE

SECTION 1 INTRODUCTION .................................................................. 1

1.1 General Description ................................................................... 1

1.2 Features ..................................................................................... 1

2.1 Accessory Items......................................................................... 1

SECTION 2 INSTALLATION .................................................................... 2

2.1 Unpacking.................................................................................. 2

2.2 Battery Installation ..................................................................... 2

SECTION 3 OPERATION ......................................................................... 3

3.1 Controls and Indicators.............................................................. 3

3.2 Operating Procedure.................................................................. 5

SECTION 4 SERVICE INFORMATION .................................................... 5

4.1 Verification Check ...................................................................... 5

4.1.1 Functionality Check ................................................................... 5

4.1.2 Accuracy Check ......................................................................... 6

4.2 Calibration for Model 871A ........................................................ 6

4.2.1 Equipment Needed .................................................................... 6

4.2.2 Environmental Conditions .......................................................... 6

4.2.3 Setup.......................................................................................... 7

4.2.4 Calibration Procedure ................................................................ 7

4.3 Calibration for Model 872A ........................................................ 8

4.3.1 Equipment Needed .................................................................... 8

4.3.2 Environmental Conditions .......................................................... 8

4.3.3 Setup.......................................................................................... 8

4.3.4 Calibration Procedure ................................................................ 9

4.4 Disassembly for Model 871A and Model 872A.........................10

4.5 Troubleshooting Guide .............................................................11

4.5.1 DC Voltage checks Model 871A ...............................................12

4.5.2 DC Voltage Checks Model 872A ..............................................12

4.5.3 Waveform Checks Model 871A ................................................13

4.5.4 Waveform Checks Model 872A ................................................13

SECTION 5 SPECIFICATIONS FOR MODEL 871A

AND MODEL 872A .............................................................13

5.1 Parts List ...................................................................................16

i

SECTION 1 INTRODUCTION

1.1 GENERAL DESCRIPTION

The OMEGA
ultrasensitive hand held instruments. Low power LSI devices combined
with a large 0.6" (15 mm) LCD, deliver reliability, extended battery life, and
an extremely readable readout. One nine volt battery will deliver 100 hours
of continuous operation.

The 871A and 872A are operationally identical except for minor differences
related to each model’s thermocouple input: Model 871A is designed for
use with type K (Chromel-Alumel) thermocouples; Model 872A is designed
for use with type J (Iron-Constantan) thermocouples.

Cold junction electronic circuitry in the Model 871A and Model 872A
automatically compensates for ambient temperature changes. A special
integrating A/D converter corrects for thermocouple non-linearity during
each digitization cycle. The resulting conformity to the standard
thermocouple voltage table is within 1ºC over the entire measurement span of
the instrument.

Although the 871A and 872A are ideal for temperature measurement in the
field, they also function well as bench instruments when equipped with the
optional tilt stand. The Model 871A and Model 872A provide dual inputs,
selectable scales (ºF/ºC), 1.0º and 0.1º resolution, and an analog output.
The versatile dual input configuration permits two point temperature
measurement such as those required in process monitoring. The analog
output allows interfacing with chart recorders or data acquisition system’s
functioning as an electronic ice-point reference.

1.2 FEATURES

• Wide temperature range • Dual thermocouple inputs

• Selectable scales (ºF/ºC) • Analog output

• 0.1º and 1.0º resolution • Heavy duty construction

• 0.25% accuracy

1.2.1 ACCESSORY ITEMS
SC-GG-[*]-30-36-SMP-M Thermocouple sensor (supplied with

KS-871 Tilt stand
SC-800 Soft carrying case
880-A2 Deluxe carrying case
U9VL 9 V lithium battery
SMP-[*]-M Subminiature thermocouple connector, male
SMP-[*]-F Subminiature thermocouple connector,

OS-201-1 2 oz. jar of high thermal conductivity paste

*Insert thermocouple type: J for Model 872, K for Model 871

®

Model 871A and Model 872A Digital Thermometers are

unit) if purchased separately.

female

for fast surface measurements

1

SECTION 2 INSTALLATION

2.1 UNPACKING

Remove the Packing List and verify that all equipment has been received. If there
are any questions about the shipment, please call OMEGA Customer Service
Department at 800-622-2378 or [phone].

The following items are included:

Quantity Description

1 871 or 872 Digital Thermometer
2 Beaded Wire Thermocouples
1 TAS Transition Adapter
1 9 Volt Alkaline Battery
1 Operator’s Manual

Upon receipt of shipment, inspect the container and equipment for any sign of
damage. Take particular note of any evidence of rough handling in transit.
Immediately report any damage to the shipping agent.

The carrier will not honor any claims unless all shipping material is
saved for their examination. After examining and removing contents,
save packing material and carton in the event reshipment is necessary.

2.2 BATTERY INSTALLATION

Turn the model 871/872A off and disconnect the input probes before
replacing the battery. Put the cover back into place on the battery com­partment before resuming use of the instrument.

NOTE

WARNING

A 9 V battery is supplied with the instrument but not installed. To install the
battery, remove the cover from the battery compartment by sliding it off in the
direction of the arrow located on the battery cover. The battery connector snaps
on and off the terminals of the battery. Improper installation of the battery will
cause the connecting wires to be severed by excess strain. Proper installation
requires that the battery be positioned in such a manner (see Figure 2-1) that the
leads protruding from the boot of the battery connector face toward the outside
of the battery compartment. If the instrument is going to be stored for a long
period of time or in a high temperature environment, remove the battery to
prevent damage due to leakage.

2

Figure 2-1. Battery Installation

SECTION 3 OPERATION

The Model 871A is designed to work with any type K thermocouple probe or sen­sor, fitted with an OMEGA miniature thermocouple connector SMP-K-M or industry
equivalent.

The Model 872A is designed to work with any type J thermocouple probe
or sensor, fitted with an OMEGA miniature connector SMP-J-M or
industry equivalent.

3.1 CONTROL AND INDICATORS

Figure 3-1 and Table 3-1 illustrate and describe the controls and indicators on the
871A and 872A.

Figure 3-1. Model 871A Controls and Indicators

*Model 872A has same controls and indicators, only range selections differ.

3

TABLE 3-1

MODEL 871A AND MODEL 872A

CONTROLS AND INDICATORS

ITEM CONTROL/INDICATOR FUNCTION

1. ON/OFF switch Turns unit on or off.

2. Scale and range selector Allows user to select: ºF or ºC scale,
any of four possible thermocouple
ranges, and 1.0º or 0.1º resolution.

3. Thermocouple selector Allows user to read either of two
thermocouples by simply turning
the dial.

4. Thermocouple input jacks Allows direct connection of two
thermocouples to the unit via an
OMEGA miniature male connector.

5. Analog output jack, The analog output is a nonlinearized,

+mV OUT and -mV OUT cold junction compensated, amplified

thermocouple output. (Not isolated
from selected TC input.) Use a
recorder to monitor temperature or
a sensitive DMM to make higher
resolution reading. Refer to mV
output specifications for mV output
to temperature ratios.

6. Low battery indicator When the battery level is low, BAT
will appear in upper left corner of
the display. Battery should then be
replaced to avoid error erroneous
readings due to battery failure.

7. Overrange/open When an overrange indication or

thermocouple indication open thermocouple condition exits,

a 1 followed by blanked digits will
appear in the display.

4

3.2 OPERATING PROCEDURE

1. Turn power on.

2. Select scale and range (see Tables 3-2 and 3-3).

3. Select thermocouple TC1 or TC2.

4. Connect one or two thermocouples to the input jacks.

5. Connect a recorder to the analog output to monitor temperatures,
or connect DMM to make high resolution readings, if desired.

MODEL 871A TEMPERATURE RANGE

Range Span Resolution

200°F -40.0° to 199.9°F 0.1°F

2000°F -40° to 1999°F 1°F

200°C -40.0° to 199.9°C 0.1°C

1370°C -40° to 1370°C 1°C

MODEL 872A TEMPERATURE RANGE

Range Span Resolution

200°F -40.0° to 199.9°F 0.1°F

1400°F -40° to 1400°F 1°F

200°C -40.0° to 199.9°C 0.1°C
760°C -40° to 760°C 1°C

TABLE 3-2

TABLE 3-3

SECTION 4 SERVICE INFORMATION

4.1 VERIFICATION CHECK

4.1.1 Functionality Check

Attach the GG-TC-K-24-36-SMP beaded wire thermocouple probe
(supplied) to the Model 871A and the GG-TC-J-24-36-SMP beaded wire
thermocouple probe (supplied) to the Model 872A. Hold the sensor end
between two fingers. The reading should change from ambient to between
77º to 104º F (25º to 40ºC).

5