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50S & 50D
Thermometer
Calibration Information
WWarning
These service instructions are for use by qualified personnel only. To avoid
electric shock, do not perform any servicing unless you are qualified to do so.
Introduction
This document contains specifications, general maintenance information, performance tests, calibration
procedures, and a list of user replaceable parts for the Fluke 50S and 50D Thermometers, hereafter referred
to as “the thermometer”.
Service
To contact Fluke, order parts,
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50S & 50D Thermometer Calibration Information International Symbols Table 1 identifies the international electrical symbols used in this document. Table 1. International Electrical Symbols Used in this Document Low Battery Important information N Complies with relevant Canadian Complies with European Union directives Standards Association directives Underwriters Laboratories, Inc. Precautions and Safety Information Use the thermometer only in the ways specified in the 50S & 50D Users Manual, par
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Specifications Specifications General Weight 280 g (10 oz) Dimensions 2.8 cm × 7.5 cm × 16.6 cm (without holster) (1.1 in × 3 in × 6.6 in) Battery Standard 9 V battery (NEDA 1604, 6F22, or 006P) Protection Class III as defined in IEC 348, Safety Requirements for Electronic Apparatus Environmental o o o o Operating Temperature 0 C to +50 C (+32 F to +122 F) o o o o Storage Temperature - 40 C to +60 C (- 40 F to +140 F) o o o o 0 % to 90 %: 0 C to 35 C (+32 F to +95 F) o o o o Humidity 0 % to 70
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50S & 50D Thermometer Calibration Information Clean the thermometer case with a mild detergent and water. The pca may be washed with isopropyl alcohol or deionozed water and a soft brush. Dry the pca with clean o dry air at low pressure, then bake it at 50 C for 24 hours. Disassembly/Reassembly Thermometer disassembly is necessary to replace the battery and some interior parts (see “Replaceable Parts”, later in this document). Refer to Figure 1 when disassembling and reassembling the thermometer
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Basic Maintenance Changing the Battery WWarning • Replace the battery as soon as the low battery indicator (N) appears. The possibility of false readings increases when the battery is not fully charged. False readings can lead to personal injury. • To avoid electrical shock, disconnect the thermocouple(s) before opening the case. Caution • Do not attempt to recharge the battery. • To prevent explosion, do not dispose of the battery in fire. • Follow local laws or regulations when disposing of ba
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50S & 50D Thermometer Calibration Information Required Test Equipment Table 2 lists the required test equipment needed to perform the performance test and calibration procedures for the 50S and 50D thermometers. If the required equipment is not available, instruments with equivalent specifications may be used. Table 2. Required Test Equipment Test Equipment Required Characteristics Recommended Model Fluke 87 Series IV Digital DMM DC Voltage Accuracy: 0.5% Multimeter o Temperature Probe Accuracy:
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Performance Tests 50S Display 50D Display J K J K - + - + HOLD MIN MAX HOLD REC F C F C T1 T2 T1-T2 zf03f.eps Figure 3. Display Segments Wide Range Performance Test Procedure This test verifies the instrument specifications. If the instrument fails this test, perform the calibration procedure. If the unit continutes to fail, it should be taken to a Fluke service center. Ice Bath Construction To begin the wide range performance test procedure, first construct an ice bath using the following steps
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50S & 50D Thermometer Calibration Information 50S or 50D Thermocouple wire Thermometer + _ Ice bath 5520A Copper wire zf05f.eps Figure 4. Ice Bath Equipment Connections Ice Bath Test Use the following procedure to test the thermometer. This test should be conducted on both thermocouple inputs of the 50D. 1. Connect the equipment as shown in Figure 4. 2. Insert the Mercury Thermometer to the same depth as the thermocouple wires and verify that the ice o o bath temperature is 0.0 C ±
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Calibration Table 3. Performance Test Values Thermocouple Input Voltage Display Reading o o Type (mV DC) C F K -5.587 -182.0 ±(0.9) -295.6 ±(1.6) K -3.211 -89.0 ±(0.8) -128.2 ±(1.4) K 21.919 530.0 ±(1.2) 986.0 ±(2.3) K 54.297 1355.0 ±(2.1) 2471.0 ±(3.8) J -7.824 -197.0 ±(1.0) -322.6 ±(1.7) J 13.997 258.0 ±(1.1) 496.4 ±(1.9) J 39.442 705.0 ±(1.5) 1301.0 ±(2.7) Calibration When calibrating the thermometer, refer to Figure 5 for the proper setup connections and Figure 6 for adjustment locations. Ca
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50S & 50D Thermometer Calibration Information position until the display is locked in self-test (all LCD segments on). This thermometer is now in the Reference Junction Sensor calibration mode. Shorting out the VIEW switch grid turns off a filter so that the reading stabilizes immediately. 13. Using the 80T-150U and the Fluke 87 Series IV Digital Multimeter (DMM), measure the reference junction transistor temperature by placing the 80T-150U probe tip against Q1, located in the middle hole of the
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Calibration FLUKE 52-1601 zf09f.eps Figure 6. A1 Main PCA Adjustments Optimizing Thermometer Performance in the Negative Temperature Range Perform the following steps to optimize the thermometer performance in the negative temperature range: 1. Put the thermometer in normal operating mode. Normal operation can be achieved by turning the thermometer OFF and then ON. No other thermometer buttons should be pressed during the power cycle operation. 2. Insert a known good thermocouple in an ice bath
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50S & 50D Thermometer Calibration Information 5. Allow the system to stabilize, then adjust T1 or T2 offset adjustments for a temperature display equal to the reading of the lag bath reference thermometer. 6. Calibration of the thermometers is complete. Disconnect all test equipment from the instrument. 50S or 50D Thermometer _ + Thermocouple wire Mercury thermometer (0.02°C resolution) Lag bath (room temperature water) Immersed to approximately same depth zf06f.eps Figure 7. Room Temperatu
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Replaceable Parts Replaceable Parts Refer to Table 4 for all replacement part numbers and Figure 8 for part locations. Unless specified in the “Model Number” column, all parts are for all units. To order replaceable parts, see the “Service Centers” section of this manual. Table 4. 50S and 50D Replaceable Parts Fluke Item Part Model Number Qty. Number Description Number 1 778191 MAIN PCA 50S 1 1 778209 MAIN PCA 50D 2 1 696534 BATTERY, PRIMARY, 9V, 0-15MA All 3 4 832246 SCREW, PH, P, AM THD FORM,
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50S & 50D Thermometer Calibration Information 15 6 9 4 16 2 10 4X 5 1 12 8 7 11 2X 4X 13 3 4X zf08f.eps Figure 8. Exploded View Diagram (Model 50D is Shown) 14
