W-392 (Rev. M) HEAT-Prober® PLATINUM-RTD THERMOMETERS Models 392HP, 392E, 392E-S, 392EX, 392EX-S, 392EVX, 392M, 392M-S, 392MX, 392MX-S, 392VX, 360X and 700M INSTRUCTION MANUAL ©Copyright 2004 Wahl Instruments, Inc.
RECEIVING INSPECTION TABLE OF CONTENTS Check your new Wahl Portable Platinum HEAT-Prober Thermometer upon receiving to assure that: 1. It has not been physically damaged in transit. 2. All parts are included. Page ® Then, plug in the probe at top and turn it on to see that it reads room temperature. If a fault is determined, take the following steps: 1. Notify the Wahl factory of the difficulty. Give number and description.
TABLE OF CONTENTS (Continued) 8.3 Intrinsically Safe for Hazardous Location (-S Versions) Rate of Change with Hot and Cold Peak Hold (Option R) 18 9.0 9.1 9.2 THEORY OF OPERATION General Program Flow 19 19 19 10.0 10.1 10.2 392M TROUBLE-SHOOTING AID Scope Procedure 22 22 22 11.0 ACCESSORIES 25 8.4 17 12.0 CALIBRATION SERVICE 26 13.0 13.1 13.2 13.2.1 13.2.2 THERMISTOR — .
2.0 OPERATION (See Figure 2-1) Insert probe into jack at top. Turn on the switch at the left. The switch is 3position; the lower detent is marked “N” for normal temperature monitoring, the middle detent is “OFF” and the upper detent is marked “P” for use of the “Maxi Temp” Peak hold circuit. This will track temperature and hold the highest attained reading. The room temperature will be displayed in °C or °F as indicated.
2.4 The Batteries The 392HP, 392E, 392EX, 392M, and 392MX HEAT-Prober are powered with five size AA rechargeable nickel-cadmium batteries, 1.2 volts each. The total capacity is 650 milliampere hours at 6.0 volts. The display demands the largest power drain. Depending on the number of digits being displayed, the batteries can power the instrument for a minimum of 5 hours or for as long as 8 hours. The 392EVX and 392VX meter utilizes an LCD type display to conserve battery life.
3.0 PROBES Probes compatible with the 392 HEAT-Prober are constructed utilizing a wire wound Platinum RTD sensor with an R0 of 100 Ohms wired in a 3-wire configuration to compensate for lead length effects. To provide probe interchangeability at 0 degrees C, a balancing resistor is added to the sensor circuit and trimmed for a total resistance of 100.94 Ohms at 0°C.
4.0 SPECIFICATIONS 392 SERIES METER SPECIFICATIONS 392 SERIES METER SPECIFICATIONS Model 392HP Range -290 to 1450°F -180 to 788°C Digital Display Bright 0.33" LED 392E 392EX 392E-S 392EX-S -290 to 1450°F -180 to 788°C 392E/392E-S Bright 0.33" high LED 392EX/392EX-S Red, 0.4" high LCD 392EVX Model -290 to 1450°F -180 to 788°C Range Red, 0.4" high LCD Digital Display Resolution 0.1° below 375°F (190°C). Auto Ranges to 1˚ above 375°F (190°C). Meter Accuracy at 77°F ±0.
5.0 MAINTENANCE/REPAIR The HEAT-Prober instrument may be recalibrated, or adjusted for a particular probe in the field by following the directions in Section 6.0. However, it is recommended that calibrations and repair be done at the factory. Return the HEAT-Prober in its foam package with a description of symptoms, and a repair estimate will be made for your approval.
Keep decreasing the supply voltage until 5.5 volts is reached, as measured with a digital DVM. The meter should maintain correct operation even though the small “L” or “Lo Bat” is on, indicating a low battery. Now raise the voltage back up until the small “L” or “Lo Bat” turns off. The voltage at which this happens should be from 5.50 to 5.55 volts. Under normal operation, an additional 20 minutes will elapse from the time the small “L” or “Lo Bat” appears until the battery voltage decreases to 5.
Models 392MX, 392MVX, 392EX, and 392EVX Models 392HP, 392M and 392E Use the Circuit Board Diagrams on these pages to locate potentiometer placement of Zero Adjustment and Span Adjustment. Note that placement varies with Model. See page 28 for Model 700M Board Layout.
6.8 Fahrenheit to Centigrade Conversion The HEAT-Prober can be ordered as a °F or °C unit. The 392 will read out in °F unless a jumper is in place. When jumped to equivalent reading of what was displayed in °F will be displayed in °C. The computer makes the calculation and there is no adjustment. “D” versions will have a front power switch for selecting between °F and °C. 6.9 Open Probe Display Remove the calibrator or decade box from the meter while the power is on. The display should show -OL-.
Each HP version probe, therefore, has its specific resistor to indicate to the microprocessor the correction to be taken. 9.0 THEORY OF OPERATION 9.1 General The microcomputer, as directed by this program receives and evaluates data from the analog-to-digital converter, and delivers the proper temperature values to the display driver. The readings may be in Fahrenheit or Celsius, peak or current value. The Flow Chart (Figure 9.1) shows the operation of the program.
for the probe readings. Both use a common subroutine, “Get M.A.”, which calls “Get ND”. Control and handshaking between the converter and the computer is performed by this latter subroutine. Data is fetched in 2 bytes, first the low order 8 bits, then the high order 4 bits, the sign and over range bits. “Get M.A.” uses the converter reading to either cram or update, as directed by a counter within the computer. Main Program Platinum Heat Prober 392M Power On The program then enters “Compensate”.
10.0 392M TROUBLE-SHOOTING AID 392 SERIES TROUBLE SHOOTING PROCEDURE 10.1 Scope This section describes basic diagnostics to find the majority of the problems with malfunctioning 392M units. Equipment Required: 1. Wahl 392M Calibrator (Model Number CAL392-HT) 2. 4- Digit DVM, Fluke 8600A or equivalent. 3. Oscilloscope. 4. Power supply, Power/mate BPA-10c or equivalent. Step Problem 1. 2. Blank Display* Measure voltage at U6-19 with DVM. It should be at +4.3 ±.2V.
11.0 ACCESSORIES 392 SERIES TROUBLE SHOOTING PROCEDURE Step Problem 13. Action to be Performed Set the Wahl Calibrator to 212°F Proceed to and insert into the T/C connector. next measUse DVM to measure the follow- urement. ing voltages U3-12 should be .255 to .275V U3-13 should be .071 to .079V *U3-1 should be .580 to .620V *U3-3 should be .660 to .710V *U34 should be .660 to .710V U3-14 should be .017 to .079V U3-15 should be .580 to .620V 14. 15. 16.
12.0 CALIBRATION SERVICE 13.0 700M THERMISTOR .01°C/F RESOLUTION HEAT PROBER Recalibration service can be provided at a nominal cost, if desired. Special thermal calibration traceable to NIST is available. Standard temperature points are: 0°C, 94°C, and 250°C. Custom points are available upon request. 13.1 General Discussion The Wahl Thermistor unit measures temperature over a range of -1.00°C to 60.99°C (30.20°F to 141.78°F) with .01°C resolution.
13.2 Calibration Procedure (See Figure 13-1) 13.2.1 Equipment Required 1. Digital Voltmeter, Fluke 8600 41/2 digit or equivalent. 2. Decade resistance box with a range to 30K and resolution to one ohm. Accuracy required can be determined by using the thermistor slope at 60°C where an error of 1 ohm is equivalent to .01°C. 13.2.2 Calibration 1. Connect DVM(+) to TP2 and (-) to TP1. Turn on power switch and adjust R15 for a DVM reading of 2.110 ±.002 volts.
HOW TO USE TROUBLE-SHOOTING PROCEDURE: Locate the problem on this table and proceed with the action starting with Step 1. Note, for all DVM and scope measurements, connect the (-) lead to TP1 (GND). 14.0 700M TROUBLE-SHOOTING AID 700M TROUBLE SHOOTING PROCEDURE Step Problem 1. 2. 3. 4. 5. 6. 7. 8. 9. Blank Display* Action to be Performed If Correct Measure voltage at U6-19 with DVM. It should be at +5.0 ±0.25V. Measure voltage at Q3 output lead.
15.0 WARRANTY REGISTRATION Fill out the Warranty Registration Form included in this manual and return to Wahl. We will send you follow-up reminders about recalibration dates. 16.0 RETURN FOR REPAIR/CALIBRATION SERVICE Warranty Repair Information Please contact Wahl Customer Service at (800) 421-2853 for a Return Merchandise Authorization number (RMA) before returning your instrument to the factory. Shipping Material being returned should be packed well, preferably in the original foam shipping container.
