FLUKE FLUKE 525A
Manual de Servicio

525A
Service Manual

14: Calibrate DAC, Digital to Analog Converter Adjustment If all of the functions that are affected by the digital to analog converter (DAC) adjustment are going to be adjusted, start with step 14 which adjusts the DAC. Do not adjust the DAC unless all of the ranges affected are going to be readjusted. During normal calibration adjustment, it is necessary to adjust the DAC. However, for example, if a mistake were made in the 100 V range, the user would not want to readjust the DAC. If it were readjusted, the user would have to readjust everything that depends on that range.
To adjust the calibration of the DAC from the menu, type 14 and then press the Enter key on the PC keyboard. No external connection is necessary. The DAC adjust will execute, save the calibration constants, then display the Calibration Menu on the PC.

1: 100 mV Source to 4: 100 V Source, Adjusting DC Source Adjusting the voltage output breaks down into four distinct ranges; each can be adjusted separately using menu selections 1-4. The adjustments are done in 2 parts. The first part sets the 0 and span values. The second part is to fine adjust the zero, span, and adjusts the linearity. The example below is for the 1 V range. The other ranges use the same steps with different voltage values. Refer to Table 17 for a list of equipment used in this section.
Table 17. List of Equipment for Voltage Calibration Adjustments Manufacturer Fluke Wavetek Model FLUKE-525A/LEADS 1281 Equipment Test Lead Set DMM

1. Connect the calibrator VOLTS HI and LO to the DMM input. 2. Set the DMM to DC Volts. 3. Type 2 and push the Enter key on the PC. The following is displayed on the PC:
First Calibration Point. Enter the Volts displayed:

4. When the reading on the DMM stabilizes, type the reading value on the PC and press Enter. After the value has been entered, the following is displayed on the PC:
Second Calibration Point. Enter the Volts displayed:

5. When the reading on the DMM stabilizes, type the reading value on the PC and press Enter. After the value has been entered, the following is displayed on the PC:
Second Calibration Point. Enter the Volts displayed: Adjust the 0 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

The second part of the calibration adjustment follows. In the 10 key section of the PC keyboard, use the 8 (up arrow) to increase the output voltage displayed or 2 (down arrow) to decrease the output voltage displayed. Keep in mind the lag time between a change in output voltage to a stable display on the DMM. Make small changes then wait for a stable reading. Adjust the output so that you get a good, stable 0 V reading. When satisfied with the reading, press the Enter key.

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