HP 8753D Option 011 User Manual

F
an Troubleshooting
F
an Speeds
The fan
speed
varies
depending
upon
temp
erature.
It
is
normal
for
the
fan
to
b
e
at high
sp
eed
when
the
analyzer
is
just
switc
hed
on,
and
then
c
hange
to
lo
wsp
eed when
the analyzer
is
co
oled.
Check
the
F
an
V
oltages
If
the
fan
is
dead,
refer
to
the
A8
p
ost
regulator blo
ck
diagram (
Figure 5-8
)
at
the
end
of
this
c
hapter.
The
fan is
driven
by
the
+18
V
and
0
18
V
supplies
coming
from
the
A15
preregulator.
Neither
of
these
supplies
is
fused.
The
0
18
V
supply
is
regulated
on
A8
in
the
fan
driv
e
blo
c
k,
and
remains
constant
at
appro
ximately
0
14
V.
It
connects
to
the
A17
motherb oard
via pin
32 of
the A8P1
connector.
The
+18
V
supply
is
regulated
on
A8
but
c
hanges
the
v
oltage
to
the
fan, dep
ending
on
airo
w
and
temp
erature
information.
Its
v
oltage
ranges
from appro
ximately
0
1.0
V
to
+14.7
V,
and
connects to
the A17
motherb oard
via
pin
31
of
the
A8P1
connector.
Measure the
voltages
of these
supplies
while
using
an
extender
b
oard
to
allo
w
access
to
the
PC
b
oard
connector,
A8P1.
Short
A8TP3
to
Ground
If
there
is
no
v
oltage
at
A8P1
pins
31
and
32,
switc
h
o
the analyzer.
Remo
v
e
A8
from
its
motherb
oard
connector
(or
extender
b
oard)
but
k
eep
the
cable
A15W1
connected
to
A8
(see
Figure
5-5
).
Connect
a
jumper
wire
b
et
w
een
A8TP3
and
c
hassis
ground.
Switc
h
on
the
analyzer.
If
all
the
green
LEDs
on
the
top
edge
of
A8
ligh
t
(except
+5
VD),
replace
the
fan.
If
other green
LEDs on
A8 do
not
ligh
t,
refer
to
\If
the
Green
LEDs
on
A8
are
not
All
ON"
earlier
in
this
pro
cedure.
DRAFT
3/21/106 15:12
Power Supply Troubleshooting 5-19
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HP 8753D Option 011 Specifications

General

Brand	HP
Model	8753D Option 011
Category	Measuring Instruments
Language	English