Keithley 236 Service Manual

SECTION
3
Maintenance
A. Disconnect
the
display
board ribbon
cable
from
J24.
B.
Place
the
instrument
on
its left
side. From
the
bottom
of
the
instrument
case, notice
that
there
are eight
screws
(seven
slotted
and
one
Phillips)
securing
the
digital
board
to
the
three
mounting
rails.
The
Phillips
head screw
installs
into
a kep
nut
on the
other
side of
the board,
Remove
this
screw
first
and make
sure
not
to lose
the kep
nut.
c.
Remove
the
other
seven screws
that
secure
the
digitalboard
to the mounting
rails.
Be sure
not to
let the
digitalboard
fall when
the
last screw
is re
moved.
D.
Place
the
the
instrument
in
the
normal
upright
position
and
remove
the
digital
board
from
the
case.
E. Remove
the
top
and bottom
shield
for the
digital
board.
This
shield
assembly
is secured
to the
board
by four
screws.
Note
that on
the Model
237, the
bottom
shield
for
the resonant
converter
must
firstbe
removed.
This shield
is also secured
to
the
digital
board
with
four
screws.
9,
Remove
the display
board
as
follows:
A.
At
the front
panel,
pull off
the rotary
knob.
B. Remove
each
of
the four
decorative
strips
from
the
side panels
as follows:
a. From
inside
the
case, place
a
thin
blade
screwdriver
into
one
of the
holes
where
the
decorative
strip
is
secured.
b. Carefully
push outwards
until
the
strip
dis
engages
from
one
of
the fasteners.
c,
Pull
the
strip
away
from
the side
panel.
Note:
To
reinstall,
align
the
strip
in the
re
cessed
part
of the
side panel and
press
the
strip
at
the
locations of the
fasteners.
c.
Remove the
four
screws that
secure
the front
panel
assembly
to the
side
panels and disengage
the
front
panel
assembly from
the chassis.
D.
Loosen
the
four
Allen set screws
securing
the
bezel
assemblies
to the
front panel.
Remove
the
bezel
assemblies
from the front panel.
E.
Lift
the display
board
away
from
front panel.
10.
The instrument
can
be re-assembled
by
reversing
the
above
procedure.
Make
sure that all
parts
are
prop
erly
seated and
secured,
and
that all
connections
are
properly
made. To
ensure proper
operation,
shields
must
be
replaced
and
fastened
securely.
CAUTION
To
prevent
damage
to
unit
or internal
circuit
boards,
use
#6-32 x
1/4“
long Phillips
pan
head
screws
provided
in
kit
to secure
bottom
cover after
removal
of
feet.
WARNING
To
ensure
continued
protection
against
safety
hazards, verify
that
power line
ground
(green
wire
attached
to
ac
power
re
ceptacle)
and
fan
ground
are
connected
to
the
rear
panel.
3-8

Keithley 236 Specifications

General

Brand	Keithley
Model	236
Category	Measuring Instruments
Language	English