Tektronix T912 - Page 59

Service Information—T912
NOTE
After replacing a
power
transistor,
check
that the
collector is not
shorted to
ground before
applying
power.
Fuse
Replacement
The
line-voltage
fuse, F700,
is
located
next to
the
POWER ON
switch, S700, on
the Interface
board.
The high
voltage
fuse, F722, is
located on the
Power Supply
board.
Refer
to the
Replaceable Electrical Parts
list for correct
fuse values.
Thick
Film
Resistor
Replacement
To
remove
the thick film
resistors,
first remove the
solder from the pins
and
then remove the
resistors.
2. Re-insert
connector into its
hole in
plug-in
portion of
holder.
NOTE
Holder
positions
are
numbered
(number
one Is
identified with a triangle).
3. Bend
grooved
part of holder so
that
connector
is
inserted
into groove.
When
plugging
connector
holders onto board
pins, be
sure
to
match triangle
mark on
holder
with triangle
mark
on
circuit board.
To
replace
the thick film resistor,
R444, match the pins
on
the
resistor
with the holes
in the circuit board.
Re-
solder
all of the pins to
the
circuit board.
Shaft-Knob
Removal
1.
Grip
knob end with one hand
and
shaft end with other
hand.
Interconnecting
Cable and
Pin Connector
Replace-
ment
The
interconnecting
cable
assemblies
are
factory
assembled.
They
consist
of machine
installed
pin connec-
tors
mounted in
plastic holders.
The
plastic holders are
easily replaced
as
individual
items,
but if the connectors
are faulty,
the entire
cable
should be replaced.
It is possible
for
the pin connectors
to become
dislodg-
ed from
the
plastic
holders.
If this happens, the
connector
can
be
re-installed
as follows (see Fig.
5-5).
1 . Bend grooved
portion of
holder
away from cable as
shown.
2. Pull on knob,
while
pushing on shaft, to free
recessed
portion of
shaft
from retainer bushing (see
Fig. 5-6). Some
shaft-knobs
may require
considerable
force to remove.
RETAINER
:
BUSHING ;
./
\
RECESSED
PORTION
OF
SHAFT
:
BUSHING
EXPANDS
AS
SHAFT-KNOB TS
IS
REMOVED
HSi
1907-42
Fig.
5-5.
Pin connector
replacement.
Fig.
5-6.
Shaft-knob
removal.
5-12
REV. A APR
1977