Accutorr Plus Service Manual - Mindray

7.6.2 Water Bath Method
1. Prepare a water bath set to 89.6 to 110.0 F as a temperature reference. Confirm
temperature with a separate precision thermometer.
2. Snap a protective sheath onto the temperature probe, and immerse into the reference
water bath for 30 seconds, or until the temperature display stops flashing. Record the
temperature shown on the temperature display.
3. Apply the correction factor, shown in table 7-13, to obtain the calibrated measurement.
Table 7-13
Celsius Readouts Fahrenheit Readouts
Range Subtract Range Subtract
32.0 to 41.0 0.6 89.6 to 102.0 1.1
41.0 to 43.0 0.5 102.1 to 106.0 1.0
106.0 to 110.0 .5
4. Compare readouts after correction factors are calculated. Proceed to System Calibration
Procedure if readings are out of specification.
7.6.3 System Calibration Procedure
1. Connect a fresh 9 volt battery or an external power supply set to 9 .1V to the
predictive thermometer. NOTE: Newer modules do not contain a 9V battery. Skip
this step.
2. Set SW2-3 to closed position (the switch is towards the PCB). Connect resistor decade
box to the temperature probe connector. Set the decade box to 8343 ohms, 2 ohms.
NOTE: (All other settings of SW2 should be in the open position; away from the PCB.)
3. Connect the DVM to J4-2 (-) and J4-7 (+) output jacks.
4. Jumper J4-2 and ground terminal ( J2-1) jacks.
5. Switch power supply on.
6. Adjust R1 until a reading of 100 mV, 5mVisontheDVM.
7. Adjust the decade box to 4746 ohms, 2 ohms. Record the voltage displayed on the
DVM.
8. Connect the DVM + lead to J4-4. Adjust R2 until the DVM reading is the same as
the one recorded in step “7”, 1mV.
9. Remove all jumpers and test leads. The calibration is completed.
10. Set the decade box back to 8343 ohms. Power cycle the unit (switch off then on).
The initial start-up temperature of 85.0 o F should be displayed.
Accutorr Plus Service Manual Revised 01/11/00
7-15
Chapter 7 - Calibration