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

3-9. THEORY OF OPE RATI ON
This paragraph d iscusses about the 4284A's principle of operation, and how the 4284A's
high measurement accuracy and its fully automated measurement performance are
achieved.
The HP 4284A is composed of five block sections: power supply block section, digital con­
trol block sectio n , source block section, transducer (TR D) 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 d iagrams (Source , TRD, and VRD sections)
are shown at the end of th is paragraph.
3-9- 1 . POWER SU PPLY BLOCK SECTION
The power supply is only A1 board which supplies the dc voltage (+5 V, ± 1 2 V, ± 1 8 V, and
-21 V) to each assembly. All service information for the A1 power supply board is g iven on
the S E CTION 4. SERVICE S H E ET.
Table 3-1 0 shows the relationship between the output dc voltages from the A 1 board and
each assembly.
At
Po w e r Supp l y
;;
'
< <
". < <
A 2 , A 3 , A4 , A5 , A6 , A7 , A20 , A30 , A31 , A4 0 , A5 0
An a l o g Bo a r d s a n d D i g i t a l
Fig u re 3-3. Power Supply Simplified Block Diag ram
Figure 3-3 shows the simplified block diagram , and
A9
A13
±12V
DC-AC Converter
Keybo a r d
�
'"
A9t
A90
+5V
-21V
K e y b oa r d !
D i sp l a y
Cont r o l
All
Mo therboa r d
..j. ..j.
�
1+ � Q) '"
<
<
B o a r d s
3-21
LCD
( D i s p l a y )
+5V_MEM C Af'Q AIO
Memory C a r d
+12'JFAN
COOL I NG
FAN