Theory Of Operation; Power Supply Block Section - Agilent Technologies 4284A Service Manual

3-9. THEORY OF OPERATION

This paragraph discusses about the 4284A's principle of operation, and how the 4284A's
high measurement accuracy a n d i t s f u l l y automated measurement performance a r e
achieved.
The HP 4284A is composed of five block sections: power supply block section, digital con-
trol block section, source block section, transducer (TRD) block section, and vector ratio
detector (VRD) section. Each description of each block section is described from the next
paragraph, and the 4284A's analog circuit block diagrams (Source, TRD, and VRD sections)
are shown at the end of this paragraph.

3-9-1. POWER SUPPLY BLOCK SECTION

The power supply is only A l board which supplies the dc voltage (+5 V, ±12 V, ±18 V, and
-21 V) to each assembly. A l l service information for the A l power supply board is given on
the SECTION 4 . SERVICE SHEET. Figure 3-3 shows the simplified block diagram, and
Table 3-10 shows the relationship between the output dc voltages from the A l board and
each assembly.
Al
P o w e r S u p p l y
A M M M I U M O M M M I O N W O M I ,
I 1 4
y z y
V T V
A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , A 2 0 , A 3 0 , A 3 1 , A 4 0 , A 5 0
Figure 3-3. Power Supply Simplified Block Diagram
A9
2 1 2 5
K e y b o a r d
A A
A90
K e y b o a r d /
D i s p l a y
- 2 1
C o n t r o l
All
M o t h e r b o a r d
A n a l o g B o a r d s a n d D i g i t a l B o a r d s
3-21
A 1 3
DC-AC Converter
6 0 0 5 A C
A91
LCD
( D i s p l a y )
A 1 0
-1.5V_WM_C
Memory C a r d
1 2 V FA N
COOLING FAN