Section VII
each contain many diodes
in
series and their forward
resistance (as measured with -hp- Model 412A) can
be
as
high
as
SO
megohms while their leakage (reverse) resistance
will generally be about 100 megohms. The primary wind-
ings
of
the high voltage transformer and the CRT heater
windings have a de resistance
of
only a
few
ohms. The other
two secondary windings have de resistances
of
100
to
200
ohms.
7-25.
Crystal
Replacement.
7-26.
If
it
is
found that the
AS
filters or
A2
crystal
oscillator need a new crystal, the crystal cannot
be
exchanged individually
but
must be exchanged
as
a
matched set
of
crystals and resistors. For this reason, the
03S80-69SOS exchange assembly, and 03S80-69SlS
re-
placement assemblies
are
available. These assemblies consist
of:
Item
Qty Description
1 1
AS
IF Filter Board, 03S80-66SOS
(ExchangeAss'y, 03S80-69SOS, con-
tains a rebuilt
AS
Board; Replace-
ment Ass'y, 03S80-69SlS contains
a new
AS
Board).
2
1
0410-0480 Crystal Set (This
is
a
matched set
of
six crystals.
Five
of
the crystals are already part
of
Item
1 ; the sixth cyrstal is for the
A2
Tracking Oscillator).
3 1
A resistor matched to the sixth
crystal supplied by Item
2.
7-27.
If
you need a new crystal, order the exchange or
replacement assembly through your local
-hp-
Sales
and
Service Office. Exchange credit can only be given
if
you
return both your old 03S80-66S05 board and the appropri-
ate crystal and matching resistor from the
A2
board.
Always
use
care when removing these crystals,
as
undue
stress on the leads can damage the
glass
encapsulation.
NOTE
This 03S80-69SOS exchange assembly
is
intend-
ed
as
an
aid
in
crystal replacement.
It
is
not
intended to
be
used in place
of
repairing other
components on the
AS
board (03S80-66SOS).
The 03S80-69Sl S replacement assembly
is
pro-
vided for those who want
to
purchase a new
AS
Assembly and do not wish
to
use the exchange
program.
7-28.
CRT
Replacement
7-6
I
WARNING
I
Use
care
when handling the CRT. Undue stress
can
cause dangerous implosion
of
the tube.
Model 3S80A
When
shipping the CRT, follow the shipping
instructions outlined
in
the Cathode Ray Tube
Warranty information at the beginning
of
this
manual.
7-29.
If
it
is
determined that the CRT needs replacement,
fill
out the Cathode-Ray Tube Failure Report supplied at
the beginning
of
this manual. To remove the CRT,
use
the
following procedure:
a.
Remove the front panel bezel (black hood).
b. Remove the metal support and plastic lens (under
bezel).
c.
Remove the rear protective CRT cover (on rear
panel).
d. Remove the CRT rear tube socket.
e.
Remove the bottom instrument cover.
f.
Through a hole in the left side, at the rear
of
the
instrument, unscrew the CRT neck clamp using a long
shaft screwdriver.
g.
Slide the CRT out. This may require moderate force.
On instruments which
have
been used extensively, it may
be
necessary
to
cut the white CRT mounting tape to
separate the CRT from the CRT tube shield. This tape
is
located on the top and bottom
of
the CRT, one inch to the
rear
of
the CRT face.
Send the CRT and Failure Report to your local
-hp-
Sales
and Service Office.
NOTES
1.
If
the
CRT
Mounting Tape
is
cut, replace
it
with a new mounting tape -hp- Part No.
0460-lllS.
2.
When
reinstalling the CRT, push the
CRT
slightly forward while tightening the
CRT
neck
clamp. This secures the plastic lens in front
of
the
CRT
7-30.
Battery
Replacement
(Option
001
only).
7-31. Each
of
the
five
.battery sticks can be replaced
individually. Do not attempt to replace individual cells
within a battery stick.
When
ordering a new battery stick,
order either the center tapped stick (-hp- Part No.
1420-0203) or the regular stick (-hp- Part No. 1420-0202).
Do
not
remove the individual battery sticks
until the entire battery pack
has
been removed
from the instrument. The battery pack
can
be
removed
by
disconnecting the battery plug (Pl)
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