Fluke 5500A, Service Manual

Page: 53 / 296

Theory of Operation
Voltage Assembly (A8)
2
2-7
2-6. Voltage Assembly (A8)
The Voltage assembly (A8) generates dc and ac voltage outputs in the range 3.3 V and
above. It also provides all the inguard supplies referenced to SCOM as described under
the heading “Power Supplies.”
Figure 2-5 is a block diagram of the voltage function and shows the signal paths for dc
and ac voltage outputs. The DAC shown in the figure is VDAC, which resides on the
DDS assembly. Note that the voltage amplifier for outputs
≥
3.3 V resides on the Voltage
assembly, but the amplifier for voltage outputs
<
3.3 V is on the DDS assembly.
+
_
+
_
VDAC
Error
Amp
DDS
AC
Converter
SCOM
SCOM
Voltage
Amp
( > 3.3V on A8,
< 3.3V on A6 )
Ref
ac
dc
Sense
Amp
dc
ac
±G
± 1
NORMAL
HI
NORMAL
LO
om007f.eps
Figure 2-5. Voltage Function