5560A/5550A/5540A
Service Manual
6
A7 Current
The A7 contains most of the circuitry that generates the ACI and DCI functions.
These circuits include:
• A low current (120
μA and 1.2 mA ranges) transconductance amplifier
• A mid-current (12 mA and 120 mA ranges) transconductance amplifier
• A high current linear transconductance amplifier for the 1.2 A and 3.1 A ranges
• A class D 30 A transconductance amplifier for the 12 A and 30 A ranges
• Averaging ac/dc converter
• Precision shunts and shunt amplifier
• The loop error integrator
The A6 DDS provides the precision dc reference and the aci waveforms.
A8 High Voltage
The A8 contains all circuits to generate acv and dcv above 12 V.
The A8 is comprised of:
• A 120 V, 100 kHz dc coupled amplifier
• A 1000 V, 10 kHz dc coupled amplifier
The 120V amplifier is also routed through a step-up autotransformer to generate 120 V to 330 V from
10 kHz to 100 kHz. The A8 also contains the sense dividers and buffers for the 330 V and 1000 V
ranges.
A12 Supply
The A12 contains all power supplies for the in-guard circuits.
Calibration Verification of the Product
Verification is the process of measurement data evaluation collected during the process of calibration
and evaluating whether the data is within the published specifications for the Product. Verification is
recommended annually for 5550A and 5560A, and biannually for 5540A. Calibration verification should
also be done before and after normal periodic adjustment or repair of the Product. Verification also
serves to check that internal calibration processes are in control.
Notes
Performance limits specified in the test record tables in this section are based on the 90-day
specifications for the 5560A at a 99 % level of confidence. For the 5550A, 5540A and/or if
limits to other specifications are necessary, the test records must be modified. A description of
how to determine a guardband test limit is included in this section. This manual is not updated
for changes to specifications. Before you do a verification, download the latest specifications
from Flukecal.com
.
Equivalent equipment and methods, either manual or automated, may be substituted for the
verification tests as long as the same points are tested, and equipment and standards used
provide for adequate (determined by process requirements) test uncertainty ratio (TUR). If
standards are less accurate than specified, appropriate tolerance limit and/or accuracy
reductions must be made to achieve equivalent results.
The verification points are selected based on knowledge about the hardware and the electronic circuits
of the product. Although a limited set of the product capabilities, these calibration verification points are
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