Text from Service Alert SA-1330
S/N affected: All
Service Alert Date: 1-Aug-1996
Units affected: All
Purpose: Visible Noise on DC Output Signal
Fluke Authorized Service Centers have noticed a noise problem on DC Outputs from the 5500A normal output terminals. These spikes are particularly noticeable when programming a DC Voltage in the 33 Volt range of the calibrator and viewing the output with a digital storage oscilloscope. These spikes are due to digital noise from the clock on the in-guard processor.
The noise, however, does not affect the utility of the output as a meter calibrator. This particular output is used only for meter and not for scope calibration. The normal meter workload of the 5500A will not register these spikes. The frequency response of the input circuitry that is typical of these meters is not sufficiently broad to detect them. Any noise from these spikes is taken into account in the floor specs for the individual ranges.