Fluke 8508A - Page 36

8508A
Service Manual
2-4
A6 Rear Input
Assembly
A5 Bezel Assembly and
A5A1 Display PCA
Rear Panel
Keyboard and
Display Memory
IEEE (GPIP)
to
Serial
IEEE-488
(GPIB)
Optically Isolated
Serial Interface
Relay Control and
Relay Drivers
Range Switched
Precision Shunts
10:1
DC
Preamp
Range Selection
AC
Preamp
Range Selection
DC V
I DC
and
I AC
AC
AC + DC
Input Signal
Switching Relays
Out-Guard Power Supply
+5 V +8 V, +17 V
Line
Power
A1 DC PCA
A2 AC PCA
A3 Ohms PCA
A4 Digital PCA
Input Select
Input SelectInput Select
Input Select
2-Wire
4-Wire
Range
-15 V
I to R Converter
Rectifier
RMS
Converter
DC AMP
(Chopper
Stabilized)
AD MUX
Internal
Reference
In-guard
Out-guard
In-guard
Power Supplies
250 VAC
+5 V +8 V
+15 V
+36 V
Lo-Pass
Filter
Output
Buffer
A to D
Converter
(ADC)
Internal Bus
Input Signal Bus
–8 V
avw003f.eps
Figure 2-1. 8508A Functional Block Diagram