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HP 811 OA Service Guide
4-8 Tr oubles h ootin g
Caut
i
on
So m e voltages on th e Prim ary Sect io n
o
f t he
P
ow er S upply are
dan gero u s and can k ill .
F
or
y
our own safet y do
n
ot touch th ese
p
arts .
Using an isolat in g tran sfor m er
m
ay p re v ent t h ese vo ltages
f
rom b eing
f
atal, but e lectrical s h ock s
f
rom t he uni t can cau se seri o u s di scomfor t,
es p eci al ly on cap acitors C406, C407 and C408 (see Fig u re 4-4 for
t heir posit i on ) .
Getti n g Started
Before
y
ou start troubles h oot ing on t h e
P
ower Supply B oard so me
setting-up is needed . Fi gure 4-5 sho w s what t h e set up loo k s like
whe n you are ready to start . You
n
eed the foll owin g e quipmen t :
REAR
PANEL
1 . The main
c
h ass i s o f the HP 8110Α
2 . An isol atin g
m
ain s tran sformer
3 . An Oscill oscop e wi t h
g
r ounding to t he
m
ain s eart h
4 . Α Hi gh-imp edance Vo lt meter
5 . Α 100 Ω res istor, 5 W .
Fi rst re m ov e t he in str ume nt co v er an d t h e
P
o w er S upply B oard, as
s h o wn
i
n Fi g u re 4-5 . Pl ace t he
P
C Board in fro n t of yo u on t he
be n ch , wi t h
t
h e instrum ent ch assi s be hin d it, as s hown in Fi g ure 4-5
HP
8110Α
t
P
OWER
S
UPPLY
B
OARD
ιSΟιΑΜΝG
M
ANS
T
R
A
N S FORMER
LAWN S POWER CONNE CTO R
A
ND LINE FILTER
MAINS FU SE
5 .
ι
all ,
Ι 00 Ω 51Ν
R
ESISTOR
F
ig ure 4-5 . Test Setu p for
t
h e
P
ower S u p ply
B
oard
On th e Power S upply B oard :
1 . Connect t h e cable
f
rom th e isol atin g main s tran sformer to t h e
m
ai n s
p
ow er conn ector
2 . Connect t he 2
f
an s to J402 an d
J
403 . This is essent i al as t h e
P
ower S upply will n ot r un wi t h t h e fan s d i sconn ected
3 . Connect t he 1009 res i stor bet wee n t h e -5 .2 V test
p
o int an d t he
AG ND (O V ) test po in t
4 . Apply p o w er to t h e isol atin g tra n s former and obser ve t he
f
an s .
If
t
he
f
an s are
n
ot runni n g :
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