Fluke 12B, Service Manual

Page: 30 / 53

Maintenance
Calibration Adjustments for Models 12B and 18
3
3-9
Calibration Adjustments for Models 12B and 18
To ensure that the meter performs to specifications, make calibration adjustments
annually using the following procedure:
1. Set the calibrator for 0V dc. Put the meter in the 4.000V dc range.
2. Connect the calibrator to the [+] and COM jacks on the Meter.
3. Apply an input of +4.000V dc ±0.25%
The meter display should read between 3.997-4.003V. If it does not, adjust R4 (see
Figure 3-4) as described below.
To adjust R4, proceed as follows:
1. Remove any input signals to the meter.
2. Remove the four screws on the back and separate the case bottom and case top.
Notice that when you do so the battery remains in the case bottom and power to the
meter is disconnected.
3. Observing correct polarity, connect a 9V battery to the battery contacts using easy
hook jumpers or alligator clip leads (see Figure 3-4).
Note
To avoid stretching or bending the battery contacts, connect leads to the
base of the contacts as shown in Figure 3-4.
4. Set the calibrator for 0V dc. Put the meter in the 4.000V dc range.
5. Connect the calibrator to the [+] and COM jacks on the meter.
6. Apply an input of +4.000V dc ±0.25%
7. Adjust R4 (see Figure 3-4) so that the meter display reads between 3.997 and
4.003V.
StockCheck.com