Eberline RO-2 - Troubleshooting Common Issues

MODEL КО-2
CAUTION
Amplifier Al is highly susceptible to damage
from static charges. When the cover is
removed, take care that no item, including
batteries, be brought in contact with the
RO-2 assembly that has not first been
grounded to the chassis of the RO-2. Grasp-
ing the chassis of the RO-2 with one hand
and touching the item concerned with the
other: should eliminate any static charge.
Soldering irons must be clipped to the
chassis prior to touching any part of the
RO-2. For added protection when working
on the instrument, remove batteries and clip
chamber
terminals
1,
3,
4,
7
and
8
(counting
clockwise
with
the
chamber
face
toward
viewer)
together.
Remove
the
clips
before
re-
installing batteries.
2.
To
remove
the
desiccant
box,
pull
open
the
nylon
retaining
straps
and
slip
the
plastic
tube
off
the
pipe
at
the side òf the'chamber assembly.
3.
То
separate
the
chassis
plate
from
the
cover,
remove
the
four
screws
at
the
corners
of
the
chassis
plate
and
lay
the
plate
over
to
the
side.
With
this
done,
access
to,
the
range
switch,
the
calibration
poten-
tiometers;
zero
control,
meter,
and
magnet
swing
arm
are
provided.
4.
To
remove
the
meter,
remove
the
instrument
han-
dle,
the
wires
to
the
meter,
and
the
three
screws
in
the
meter
bezel.
This
frees
the
meter.
5.
To
gain
access
to
the
detector
electronics,
loosen
the
two
screws
holding
the
chamber
mounting
brackets
to
the
chassis
plate.
Rotate
the
chamber
assembly
slight-
ly
to
allow
the
assembly
to
come
free.
Observe
caution
.
paragraph
above.
Cleanliness
inside
the
chamber
assembly
18
of
the
utmost
importance.
6.
The
inside
of
the
ion
chamber
can
be
reached
by
removing
the
ring
which
clamps
the
Mylar®
face
and
then
removing
the
face.
Once
the
face
is
removed,
the
center
electrode
may
be
removed
by
unscrewing
it
from
the
center
pin.
If
the
pin
starts
to
rotate,
hold
it
with
`
pliers
in
the
electronic
section.
7.
Removal
of
the
four
screws
in
the
corners
of
the
slide
holder
on
the
bottom
of
the
case
will
remove
the
slide
and
the
holder.
D. REASSEMBLY
1.
In
general,
for
reassembly
reverse
the
procedure
used
in
disassembly.
`
10
2. The chamber face and the thin window under the
slide аге both 1-mil-thick (0.001-inch) aluminized
Mylar? film. The window on the can is glued to the
aluminum surface with electrically conductive adhesive,
and the window on the chamber is clamped against a
conductive: rubber gasket so that proper electrostatic
fields can be maintained, especially inside the chamber.
If only one side of the Mylar? is aluminized, make sure
that the aluminized side is toward the inside of the
chamber in both cases. To replace the chamber face, lay
the Mylar? over the rubber gasket and press on the
clamp ring evenly to avoid large wrinkles. In very moist
conditions it may be advisable to flush the chamber with
dry nitrogen just prior to closing it with the face. If this
is not done, it may be necessary to temperature cycle the
unit later as described in part A of this section.
3. The magnet swing arm assembly should be ad-
justed so that it is against the right hand stop when the;
range switch is at OFF through ZERO, is against the. ·
left hand stop when the switch is at 5000 and 500, and ::
should be centered when the switch is at 50 and 5. Тһе,”
magnet should just clear the meter insulators as it
swings past. The swing arm operation is adjusted by
moving its mounting bracket, moving the switch cam
assembly, and by bending the arm where necessary.
Make sure the magnet cannot contact the meter case `
under any conditions of movement.
E.
TROUBLESHOOTING
~.
The
schematic
diagram
Figure
6-1,
the
system
block
diagram
Figure
3-1,
and
Section
III
“Theory
of
Opera-
боп”
are
the
primary
aids
to
troubleshooting.
7
1.
Тһе
instrument
has
по
active
electronic
сот-
ponents
except
for
amplifier
А1.
Then,
the
most
likely
sources
of
trouble
would
be
the
amplifier,
a
broken
-
wire,
poor
batteries,
or
leakage
in
the
high
impedance
areas
of
the
chamber
assembly.
f
2. If the meter remains pegged and will not zero when
the ZERO position is selected, check for proper bat-
tery
voltages.
Try
pressing
the
magnet
down
against
the
chassis plate to make sure that S2 is pulled in. Using the
schematic
Figure
6-1
as
a
guide,
check
for
proper
voltages at the chamber assembly terminals. Terminal 1
should
be
at
plus
battery
voltage,
terminal
2
should
be
slightly
less
negative
than
the
negative
battery
voltage,
terminal
3
should
be
ground,
etc.
If
these
voltages
ap-
pear
normal,
but
terminals
5
and
8
are
of
the
same
polarity,
the
amplifier
is
probably
defective
and
should
be
changed.
Observe
how
the
old
amplifier
was
installed
and install the new one the same way.
CHANGE 2