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Secondary Section
This
is
t h e p art of Figure 7-2 shown on t he right of
t
he dotted-lin e.
R
ectifier a nd Filter for DC
S
up plies
Thi s secti on i s on sche mati cs 4Α
a
nd 4Β
-5.2 V
S
upp ly : Direct
P
ower Co ntrolled
Thi s sect i o n i s on schematic 4Β
+32 V Reg ulato r Gate Supp ly
Thi s sect i o n i s on schemati c 4Α
HP 8110 Α Service Guide
Diodes C R408, CR409, C R421, CR422, C R423, C R 424 are bl ockin g
durin g 'on-time' . The diodes are
f
orward-bi assed during 'off time',
res ulting in h alf-w a v e r ectificat ion in the secon dary secti on . Th e
unregulated v o l tage
i
s s moothed by el ectrolytic capac itors and fil-
terd by L C
n
et works .
The reg ul ator stage
i
s
f
ollo w ed by α seco nd
L
C filter stage .
Th e -5.2 V DC o utpu t
i
s direct ly pow er -controlled . The outpu t
vol tage
i
s appli ed to pin 1 of the PWM control unit, vi a the
op to-coupler C P402 . The voltage applied to pin 1 of U 401
deter mines t he 'on-time' . The -5 .2 V DC
i
s reg ul ated in t he
seco ndary sect i on by t he reg ulator VR 406 .
±32
V,
±12
V,
+5 .1 V
S
u pplies :
L
i n ear
P
ower Controlle d
Thi s sect i o n i s on schematics 4Α
a
nd 4Β
Th e ±32
V,
±12
V,
an d +5 .1 V D C out puts are pow er controlled
by FET tran sistors op erat ing as series-pass elem ents. The +32 V
i
s
u
sed as gate supply v o ltage
f
or t he series- pass ele ment in α11 ot her
supplies. All
o
f t he v oltages are reg ulated: VR 403 (+12
V), V
R 404
(-12 V), VR 405 (+5 .1
V),
VR 410 (+32
V),
an d VR 411 (-32
V) .
F
or correct op eration of t he +32 V regulator the gate supply vo ltage
mu st be at
l
east 10 V
h
igher than
t
he 32 V ou tput at C E 434 . Th e
vo l tage
i
s do ub led wit h
t
he circuitr y con si sting of C443, C R430,
CR 431,
R
430, C E444, and
Z
ener diode Ζ404 . To protect
V
R401
f
rom
ov ervo ltage (>40
V),
Ζ410
i
s added .
Functional Desc ription 7- 9
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