Agilent Technologies 4339B - Power Supply Section; Power Supply Section Block Diagram

not
lose its
data when
power is
turned
o.
The
EEPROM
is
mounted
in
a
socket
for
easy
replacement.
Jumpers
and switches
set
the
4339B
conditions
.
Refer
to
Appendix
B
for
more
information.
P
ower
Supply
Section
Figure
4-7
shows
the
P
ower Supply
Section block
diagram.
Figure 4-7.
P
ower
Supply
Section
Block
Diagram
The
ac
line
power
is
connected
to
the
A5
A
C
Inlet
Board
Assembly
,
which
consists
of
a
fuse
,
line
switch,
voltage
selection
switch,
and
the
varistors
.
The
voltage
selection
switch
selects the
ac
line
voltage
either
230
V
or
115
V
.
A
ccording to
the selection,
the ac
line power
is
connected
to
the
corresponding
primary
tap
of
the
transformer
.
V
aristor
,
VR1
protects the
circuit from
surge
voltage
on
the
line
power
.
VR2
blows
the
fuse
F1,
if
the 4339B
is turned
on with
wrong
line
voltage
setting
selection,
for
example
,
115V
selection
when
using
230
V
line voltage
.
Note
Because
very
high
dc
isolation
is
required
between
A3
Ammeter
assembly
and
the
other
assemblies
,
the
4339B
has
two
independent
dc
voltage supply
systems.
Both of the transformer secondary voltages are approximately 14 V
. One of the ac voltages is
rectied and ltered by circuitry on the A1 Main Board Assembly
, and produces approximately
14 Vdc. The dc voltage is applied to the DC-DC Converter to produce regulated +5 V, +
12 V, and
0 12 Vdc
. The dc voltages are supplied to all the assemblies except A3, either
directly or indirectly via the
A1 assembly
. The other ac voltage is rectied and ltered on the
A3 Assembly. A dc-dc converter on the A3 assembly provides regulated +5 V, +12 V, and
0 12 Vdc for the A3 assembly operation.
Troubleshooting 4-9