Tektronix T912 - Page 60

Service
Information—T912
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CAUTION J
The bushing and
shaft may
separate abruptly. To
avoid damage to the
potentiometer and
circuit
board, or
personal
injury, grip both
pieces firmly
during shaft-knob
removal. It
may
be helpful to grip
the shaft
with
the
tip
of a long-nose
pliers and use
a
gentle
rocking
motion to separate the shaft
from
the
bushing.
Vertical
Amplifier Replacement
To
remove the vertical amplifier
(see
Fig.
5-7)
from the
instrument;
1.
Support
the vertical
amplifier, while
removing
the
retaining
screws.
One is between
the
attenuators, one is
near R4327,
and one is near R4375.
2.
Disconnect
P4 (see Fig.
5-8) from
J4
on the Interface
board by
lifting
the entire vertical
amplifier. Be careful not
to bend
the pins.
Attenuator
Replacement
To
remove
the attenuator from the
instrument;
1.
Remove the POSITION
control knob and
shaft.
2.
Remove
the
VOLTS/DI
V
VAR knob and
shaft. To
remove
the
shaft,
loosen the set screws
holding
the shaft
to the
potentiometer and pull the shaft out
(observe
knob
orientation
for
re-assembly
reference).
3.
Pull the
VOLTS/DIV
knob and shaft out
of
the front
panel.
4. Remove the
three retaining screws
from
the
attenuator
shield and the hex
nut behind
the front panel
near the
bnc
connector.
5.
Pull the
attenuator
assembly off the
Vertical
Amplifier
board. Be
careful not to
bend
the connector pins.
To reinstall the
vertical amplifier,
reverse the
above
procedure.
NOTE
The front panel,
switches, delay
line, and
attenuators are
attached
to
the Vertical
board.
6.
To
remove
the
attenuator
shield, first unsolder the
leads to
the bnc connector.
Take
care not to touch the
body
of
the capacitor
with
a
hot soldering
iron.
Then
remove one retaining
screw from the board
side.
Be
careful not to
remove the screws
holding
the cam
switch
against
the
attenuator board.
Lift the shield off the
attenuator.
Fig.
5-7.
Circuit
board
locations.
REV.
A APR 1977
5-13