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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 calcula-
tion 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-.
If power is turned on while probe is absent, the same display should occur.

6.9.1 “Help” Display (Appears on 392E or 392M only, 392EX or 392MX
does not display “Help”)
The microcomputer is programmed to display “Help” when span adjustment
outside the normal range is attempted. If “Help” continues to be displayed, it
indicates that an incorrect adjustment is being attempted or a faulty meter.

7.0  THERMAL CALIBRATION PROCEDURE
For thermal calibration of temperature, baths are needed for immersion
probes, and surface plates are used for surface probes. However, remember
that calibrating with a specific probe will introduce the error of the probe into
the meter system. Other probes may therefore introduce greater or lesser
error, because the meter is moved away from its nominal curve. DO NOT cali-
brate a surface probe by immersion. There will be an error because compen-
sation is made at the factory for heat loss in surface probes.

Insert the probe in the unit and into well stirred, controlled ice baths at 0°C.
(Be sure it is well stirred). The temperature can vary 1°C, depending on the
layer of water the probe is in, or proximity to a piece of ice.

With the top cover removed (as explained in Section 6.2) and instrument
open, adjust until the 0.0 reading is obtained.

For span, a 250°C or higher bath, should be used. Adjust R35 until the tem-
perature reading is achieved.

8.0  392M and 392HP OPTIONS

8.1  392HP
The “HP” option allows probes to be calibrated and interchangeable over the
entire temperature range. This also results in superior system accuracies at
all temperatures. The “HP” option utilizes a Noise Rejection program which
minimizes transient noise effects.

In this version a special 4-pin receptacle is installed at the probe connection,
and the four pins are wired to the printed circuit board from the probe con-
nector side as shown in Figure 8-1. A resistor with a nominal value of 5K is
installed in each individual probe via the extra pin. 5K resistance indicates to
the microprocessor that nominal curve values in the memory shall be used.
Other values of this resistor tell the microprocessor to initiate corrections to
the nominal curve.

Close matching with a probe is achieved as follows: The probe is tested at a
specific bath temperature, and a decade box is attached where the R33 resis-
tor would be in the probe. The resistance is adjusted until the 392HP reads
the precise temperature of the bath, for example 100°C, taking out the toler-
ance of the probe. A value of 4K, for example, may be needed in the decade
box to adjust the reading by 0.2%. The new resistor value of 4K tells the
microprocessor to make an adjustment for that specific probe. The decade
box is removed, and a resistor with the same value as the adjusted box is
potted inside the 4-pin probe connector between pins 3 and 4 (See Figure 8-
2)
.

8.2  Degree F to C Conversion (Specify Suffix D)
The microprocessor provides true digital conversion for temperature
throughout the whole range of the instrument. This switch is a convenience
where dual measurement scales are needed.

8.3  Intrinsically Safe for Hazardous Operations (Order -S Models)
The standard 392M instrument is Factory Mutual classified for Class I and II,
Division I, Group D (for methane and propane), and Group G (for grain dust).
To achieve the higher level Group C rating (for ethylene gas), Group F (for
coal dust), and Group E rating (for metal dust), the instrument is required to
have an additional current limiting resistor in the NiCad battery pack.
Therefore -S Models use battery pack Model Number 11681-2, which
includes the current limiting resistor. In all other aspects, it is the same as
the standard 392M.

Содержание 392M

Страница 1: ...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 Printed in USA W 392 Rev M ...

Страница 2: ...s authorized to assume for Wahl any liablility except as set forth above Warranty Temperature Probes and Meter Accessories Wahl warrants its Hand Held Meter Temperature Probes to be free of defects in workmanship or material Due to the environmental nature of their use probes cannot be replaced without cost unless returned unused within a 30 day period Wahl assumes no liability for damages of any ...

Страница 3: ...y in all light conditions To minimize power drain the display is multiplexed The LCD display is 0 4 high with excellent contrast A large portion of the circuit is designed with low power C MOS components The result is a design which provides a low power drain operation which allows operation for 8 hours per charge for the 392E 392EX 392M and 392MX meters Battery life is 50 hours for the replaceabl...

Страница 4: ...e to conserve battery life 2 1 Meter Operation The HEAT Prober instrument has an accurate measuring range as stated on the front label The probes however may not be capable of this entire range of use Wahl probes are typically capable of 40 C to 500 C or 40 F to 900 F The digital readout will show resolution to 0 1 increments from 180 0 C to 190 C or 290 F to 375 F At approximately 190 C or 375 F ...

Страница 5: ...able of 50 hours continuous operation 2 4 1 Recharging To recharge the batteries use the recharger supplied Plug in directly to 115VAC 60 cycle wall plug and insert jack into socket on left side of HEAT Prober For overseas 220 volt lines use a Franzus converter adapter with the recharger supplied or request a 220 volt recharger 2 4 2 Continuous Operation The 392HP 392E 392EX 392M and 392MX HEAT Pr...

Страница 6: ...a body temperature it requires good contact with that body or in the case of liquids or gases good immersion and mixing A portable probe temperature sensor must have the following characteristics a a low thermal mass product of its specific heat and weight b a large area for surface contact to permit heat transfer between the object being measured and the probe sensor c a minimum of heat conductio...

Страница 7: ...thane Propane E Metal Dust F Coal Dust and G Grain Dust All 392 Models Available in F C or Dual Scale add F C or D to Model Number Dual Scale not available on S Models 392 SERIES METER SPECIFICATIONS Model 392M 392MX 392M S 392MX S 392VX Range 60 to 752 F 51 to 400 C 60 to 752 F 51 to 400 C Digital Display 392M 392M S Bright 0 33 high LED Red 0 4 high LCD 392MX 392MX S Red 0 4 high LCD Resolution ...

Страница 8: ...igure 5 1 392M Platinum Heat Prober with Wahl Calibrator Model Number CAL392HT 6 0 SET UP AND CALIBRATION 6 1 Equipment Needed A Digital voltmeter Fluke 41 2 digit Model 8600A or equivalent B Wahl Platinum Calibrator Model Number CAL392HT or CAL392LT or General Radio decade box Model 1433 1 or equivalent with standard coil cord Model 10434 01 or 10434 02 cable as used with Wahl probes C Power supp...

Страница 9: ...t a quick and accurate calibration can be achieved 6 6 1 Setup and Calculations The decade resistor box may be used as the source to perform a standard calibration A coiled cord cable with connector for the Wahl probe should be used Model Number 10434 01 This has an approximate resistance of 0 36 ohms The actual resistance should be determined for your setup and this value used in the calculations...

Страница 10: ...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 ...

Страница 11: ...e entire temperature range This also results in superior system accuracies at all temperatures The HP option utilizes a Noise Rejection program which minimizes transient noise effects In this version a special 4 pin receptacle is installed at the probe connection and the four pins are wired to the printed circuit board from the probe con nector side as shown in Figure 8 1 A resistor with a nominal...

Страница 12: ...the program Details of the components will be discussed in this section 9 2 Program Flow When Power is turned on the program will start executing instructions from address 000 the location of the top level program labeled Main The first routine called is Initialize This is a house keeping routine which establishes the starting conditions The data memory RAM is cleared the input output ports are co...

Страница 13: ...rage be crammed with new data Additionally if over range is displayed indicating on open probe lead or removed probe conditions are set for the next entry into Gaincheck to cause the compensation reading to be crammed and also that rapid updates to it are to be made on following passes This is done to accommodate changes in probes by the user so that the display will repre sent the actual probe re...

Страница 14: ... 58MHz square wave with levels from 0 to 5 volts Replace U6 If still no display go to Step 9 Replace U4 If still no dis play go to Step 7 4 Check voltage at Q4 collector It should be equal to the battery voltage or applied voltage from test power supply Proceed to next step Check for open trace from Pin 5 to Q4 C 5 Check voltage on junction of R30 and CR5 cathode Should be 5 000 005V Proceed to ne...

Страница 15: ...16 Return unit to factory for repair NOTE Does not apply to 392MX and 392M with Serial Numbers before N120 11 0 ACCESSORIES 392 SERIES CALIBRATORS Model Number Usable With Meter Calibration Points CAL392 HT 392E 392EX 392EVX 392M 392MX 392VX and 700M 58 F 32 F 212 F 284 F 752 F 50 C 0 C 100 C 140 400 C CAL392HP HT 392HP only CAL392 LT 392E 392EX 392EVX 392M 392MX 392VX Ice Point to Boil Calibrator...

Страница 16: ...s the same as the 392M which is a recharge able nickel cadmium battery pack composed of five AA size cells with a com bined voltage of 6 0 volts and capacity rating of 65 amp hours The unit is supplied with a recharger which can be plugged in at any time to maintain the charge of the battery pack Low battery condition is displayed as L in the left hand side of the display The 700M is available onl...

Страница 17: ...50 plug connector 3 Set resistance to 29 490 ohms and adjust R5 for a display read ing of 0 00 C 32 F 4 Set the decade box to a resistance of 2760 ohms and adjust R13 for a display reading of 60 00 C 140 00 F 5 Set the decade box to a resistance of 12 260 ohms and check the unit for a correct display reading of 20 00 C or 68 00 F 6 Repeat steps 3 4 and 5 as necessary for best calibration 14 0 392M...

Страница 18: ...d to next step 8 Measure voltage at pin 6 of wire harness It should be equal to the battery or power supply voltage Proceed to next step Check wire harness for broken wires 9 Replace Q1 and repeat Step 7 Done Go to Step 19 10 Unit con stantly read OL Measure voltage at U4 28 with DVM It should be 4 3 0 2V Go to step 12 Proceed to next step 11 Check voltage at U3 8 It should be 5 0V 0 25V Replace U...

Страница 19: ...u 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 Ship to WAHL INSTRUMENTS...

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