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HP 811 OA Se rvice Guide
O
u
t
p u
t
B
oar
d
Ο
PER
IOD
DATA
D
E
L
AY
TO OUTPUT
BOA
R
D 2
OF RT
E
D1
7- 2 8
Functio nal Desc ription
A
s O utpu t 1 and O utput 2
b
oards are funct ionally
s
imilar, α
descrip tion is given
o
nly
o
f
O
utput 1
b
oard . The Output
B
oard
receives α 50% duty
c
ycle signal from
t
he
P
er iod
B
oard, or where two
outpu t channels are fitted,
f
ro m
t
he optional Deske w Board . Th e
signal is first de layed and then wi dt h is set. The slopes of
t
he
l
eading
and traili ng edges are then set,
f
oll owed by
t
he amplitude
v
erni er and
the output ampli fier . Finally, the offset
v
oltage
l
evel is set . These
parameters are controlled by data
f
rom
t
he
D
evi ce Bu s Interface sent
in response to
F
ro nt
P
anel co ntrols.
Fi gure 7-7 shows the funct ional units on the Output
b
oard . Th ese
have
b
ee n numb ered
f
or easy cross-reference bet wee n
t
he descrip tion
and the diagram.
P
OW
E
R
F
I
L
T
E
R
S
SLOPE
CURRENTS
SL
O
PE
51
M f?_
J
ADJUST
DAC
V
E
~
J
1
E σ R
~ωω
r
ωε I I
CONT
R
O
L
νεRΝιF Α
CURRENTS
D
SEL
F
7ΣSΤ
Unit
Function
OF
F
S
E
T
ιι
D
EV
IC
E
BUS
INTERFACE
Figure 7-7. The Outpu t Board Functional Un its
OUT
R
I
i
ENABLE &
i PROTECT-
[ON
ι 2
Th e units, and what they do, are as
f
oll ows :
TO
C
H
A
NNEL
2
-> TO
N
Y
C
R
OP
R
OC
E
SSO
R
CHANNEL I
0Lf1"ΡΙΙΓ
1- Power filters
N
oise
i
s re moved
f
rom
p
ower applied to the
Outpu t
b
oard and additional
v
oltages are
p
roduced
2-Selftest and
A
djust DA C
The in strument checks that
i
t
i
s funct ional. Th e
A
djust DA C adjusts
v
oltages to
m
eet calib ration
sett in gs
3- Devi ce Bu s Interface
Th e Output
B
oard
u
ses thi s to co mmunicate wi th
t
he Mi croprocessor
4- Delay Generator
This sect ion provides delay after the
p
eriod
p
ulse .
Th e
D
es kew Board (if fitted)
p
rovi des additional
delay
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