Voltage Pca (A8); Main Cpu Pca (A9) - Fluke 5080A Service Manual

5080A
Service Manual

Voltage PCA (A8)

The Voltage PCA (A8) supplies dc and ac voltage outputs in the range 3.3 V and
above. It includes transformers and HV rectification for 330V and 1kV ACV and
DCV ranges. It also supplies all the inguard supplies referenced to SCOM. See
the "Power Supplies" section.
Figure 6 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 PCA. Note that the voltage amplifier for outputs ≥3.3 V resides on
the Voltage PCA, but the amplifier for voltage outputs <3.3 V is on the DDS PCA.
Ref

Main CPU PCA (A9)

The Main CPU PCA (A9) attached to the rear-panel assembly communicates
with:
•
•
•
The main CPU memory is Flash ROM. There is a real-time clock with a battery
backup.
The CPU PCA communicates with each of the analog PCAs via a digital bus.
Each analog assembly has the same bus structure:
•
•
•
The routing of signals to the front panel jacks are controlled by output relays on
the motherboard.
20
_
+
Error
Amp
VDAC
dc
ac
AC
Converter
Inguard CPU on the DDS PCA (A6)
Display assembly CPU
Serial interfaces
One or more Chip Select lines
Common data bus that connects to the motherboard, latched in by latches
A fault line that sets all modules to a safe condition if a malfunction is found
± 1
DDS
Sense
Amp
Figure 6. Voltage Function
Voltage
Amp
( > 3.3V on A8,
< 3.3V on A6 )
dc
±G
ac
SCOM
NORMAL
HI
NORMAL
LO
SCOM
yg120f.eps