COVER AS 4777699 - Caterpillar

New calibrator circuit.New Calibration Procedure to Check Reading Accuracy of the 1P3060 Pyrometer Group
Only use the calibration circuit and information that follows to check the pyrometer reading accuracy:
Circuit Conditions
1. All resistors are 1/4 watt, 20%.2. Digital voltmeter (DVM) has a maximum resolution of 100 microvolts (10 microvolts minimum) and not less than 0.1% accuracy.3. 12 VDC can be a 12 volt automotive battery or a bench power supply.4. R1 is a carbon potentiometer (volume control). The circuit does not have to be exact, but the voltage produced (made) across the resistance must be known.The input power (12 VDC) is decreased to millivolts when sent across the three parallel resistors. This is similar to a thermocouple output with 3.33 ohms resistance. The potentiometer (R1) is adjusted until the digital voltmeter (DVM) reads each of the values in the chart that follows. The pyrometer must read the temperature opposite, within 16°F.
If a bench power supply is used, the potentiometer (R1) can be zero ohms and the power supply voltage can be adjusted to give the necessary calibration voltages.