Omega 871A, User Manual

Page 1: ...http www omega com e mail info omega com User sGuide 871A and 872A Digital Thermometers Only model 871A has CE certification ...

Page 2: ...ree in France 0800 4 06342 e mail france omega com Germany Austria Daimlerstrasse 26 D 75392 Deckenpfronn Germany Tel 49 07056 3017 FAX 49 07056 8540 Toll Free in Germany 0130 11 21 66 e mail germany omega com United Kingdom 25 Swannington Road P O Box 7 Omega Drive ISO 9002 Certified Broughton Astley Leicestershire Irlam Manchester LE9 6TU England M44 5EX England Tel 44 1455 285520 Tel 44 161 777...

Page 3: ... 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 Mode...

Page 4: ... 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 req...

Page 5: ...in the event reshipment is necessary 2 2 BATTERY INSTALLATION 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 connecti...

Page 6: ...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 ...

Page 7: ...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 ...

Page 8: ...NFORMATION 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 Range Span Resolution 200 F 40 0 to 199 9 F 0 1 F 200...

Page 9: ...quipment Needed 1 DC Voltage Calibrator with 1 0 01 of setting 20 µV accuracy 2 100 1 divider 1 98 kilohm and 20 ohm wirewound resistors with 0 02 ratio accuracy or better 3 OMEGA TRC III Ice Point Reference Chamber or distilled water ice bath 4 OMEGA type K TRP Reference Probe or make a thermocouple transi tion junction see paragraph 4 2 3 4 2 2 Environmental Conditions To meet all specifications...

Page 10: ...k or ThermosTM to accommodate the transition junction b Firmly pack the flask with pea size ice chips made from distilled water and then fill the flask with distilled water c Replace the melted ice with more ice while removing excess water d Place cap on the flask and insert the transition junction into the flask Allow 20 minutes for temperature stabilization Using tap water may cause inaccuracies...

Page 11: ... Conditions To meet all specifications the conditions for calibration should be an ambient temperature of 23º 1ºC relative humidity less than 80 4 3 3 Setup 1 To make a thermocouple transition junction silver solder a piece of copper wire to each type J thermocouple wire and insulate the junction with a waterproof jacket 2 Connect the thermocouple wires from the type J transition junction to an OM...

Page 12: ...Calibration Procedure It is not necessary to disassemble the case for calibration All adjustments are accessible by removing the covers shown in Figure 4 2 1 Remove the battery and trimmer compartment covers from the Model 872A 2 Turn the Model 872A on and perform the calibration adjustments listed in Table 4 4 TABLE 4 4 CALIBRATION ADJUSTMENTS FOR MODEL 872A 9 872A Calibrator Trimmer Desired Step...

Page 13: ...ontact through the conductive elastomer strip between the circuit board and the LCD 4 To remove the PC board from the top cover grasp the TC switch assembly and lift until the input jacks become disengaged from the cover The PC board can now be removed using a slight clockwise motion to free the two switch knobs from their normal positions in the case 5 The LCD assembly will remain in the top cove...

Page 14: ...aintenance personnel who are familiar with the proper use of stan dard electronic test equipment To gain access to the PC board refer to the first three paragraphs of the disassembly instructions Utilize the Parts List Schematic and Component Layout for identifying parts and checkpoint locations The following checks should be made with the Models 871A and 872A set to the 200ºC Range 11 ...

Page 15: ...5mV U103B PIN 6 to È 150 25 mV 6 Cold Junction Voltage Ambient temperature 25º 3ºC COM to È 1 0 0 6 mV 4 5 2 DC Voltage Checks For Model 872A 1 Battery VBAT 7 V 2 Power Supplies V to È Analog Ground 2 8 0 4 V V to È Digital Ground 5 1 V 3 Reference Diode CR101 to È Analog Ground 1 23 0 03 V 4 Negative Reference Divider Reference to È Analog Ground R119 Pin mV Pin mV Pin mV 2 312 5 274 8 267 3 293 ...

Page 16: ...tangular Wave Backplane U101 Pin 20 50 Hz 5V pp Rectangular Wave SECTION 5 SPECIFICATIONS FOR MODEL 871A AND MODEL 872A GENERAL THERMOCOUPLE INPUTS Two switch selected ACCURACY 0 25 of reading 1ºC 0 25 1 8ºF for one year 64º to 82ºF 10º to 28ºC ambient EXTENDED SPAN ACCURACY 40º to 55ºC 2ºC 0ºC REPEATABILITY 0 2ºC Typical one hr constant ambient temperature TEMPERATURE COEFFICIENT 64º to 82ºF 18º ...

Page 17: ...al banana jacks POWER 9 V alkaline or carbon zinc NEDA 1604 battery BATTERY LIFE CONTINUOUS 100 hrs typical with alkaline battery 50 hrs typical with carbon zinc battery BATTERY INDICATOR Display indicates BAT when less than 10 of life remains DIMENSIONS H 7 0 178 mm x W 3 1 78 mm x D 1 6 42 mm WEIGHT 10 6 oz 300 grams FOR MODEL 871A TEMPERATURE SENSOR Type K NiCr NiAI thermocouple RANGES 200ºF 20...

Page 18: ... OUTPUT TEMPERATURE COEFFICIENT 0º 18ºC 28º 50ºC Less than 0 1 x accuracy specification ºC mV OUTPUT PROTECTION 35 V dc 42 V peak max mV to mV and selected TC input to mV or mV THERMOCOUPLE LINEARIZATION Multi scope A D with 11 piecewise linear segments between 40º and 1370ºC FOR MODEL 872A TEMPERATURE SENSOR Type J Fe CuNi thermocouple RANGES 200ºF 1400ºF 200ºC 760ºC TEMPERATURE SPAN 40 0º TO 199...

Page 19: ...4W Comp R107 Resistor 47 kΩ 5 1 4W Comp R108 Resistor 470 kΩ 5 1 4W Comp R109 Pot 2 kΩ R110 Thick Film Resistor Network R111 Resistor 10 kΩ 10 2W Comp R112 Resistor 10 MΩ 10 1 4W Comp R113 Resistor 5 1 kΩ 5 1 4W Comp R114 Resistor 1 MΩ 5 1 4W Comp R114 Resistor 1 MΩ 10 1 4W Comp R115 116 Resistor Selected 1 1 8W Mtf R115 R115 and U110 are a selected set SPECIFICATION con t mV OUTPUT Non linearized...

Page 20: ...rcuit Description Desig U101 3 1 2 Digit Single Chip A D Converter U102 Dual Synchronous Up Counter U103 U104 Low Power JFET Input Op Amp U103 U104 Dual JFET Input Op Amp U105 COS MOS Quad Bilateral Switch U106 CMOS Quad Exclusive OR Gate U107 Dual D Type Flip Flop U108 14 Stage Binary Counter U109 Linear Op Amp U109 R116 R222 and U109 are a selected set U110 Current Source U110 R115 and U110 are ...

Page 21: ...SCHEMATIC MODEL 871A DIGITAL THERMOMETER 18 ...

Page 22: ...SCHEMATIC MODEL 872A DIGITAL THERMOMETER 19 ...

Page 23: ...otherwise shall not exceed the purchase price of the compo nent upon which liability is based In no event shall OMEGA be liable for consequential inciden tal or special damages CONDITIONS Equipment sold by OMEGA is not intended to be used nor shall it be used 1 as a Basic Component under 10 CFR 21 NRC used in or with any nuclear installation or activity or 2 in medical applications or used on huma...

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