Tektronix 5441 Instruction Manual page 96

Switch Replacement. The following maintenance infor-
mation is provided for the cam switches and pushbutton
switches used in this instrument system.
C A U T I O N
E I I
Repair of cam switches should be undertaken only by
experienced repair personnel. Switch alignment and
spring tension of the contacts must be carefully main-
tained for proper operation of the switch. For assis-
tance in repair of the cam switches contact your local
Tektronix Field Office or representative.
A. CAM SWICHES
Two cam switch repair kits are available from Tektronix
Inc. The first kit is used to repair the cam switches in most
time-base plug-in units and some vertical plug-in units. The
second kit is used to repair the cam switches using the high-
frequency contact, which is used in several vertical plug-in
units.
The cam switches consist of a rotating drum with lobes,
whose position is controlled by the front-panel knobs, which
actuate spring-leaf contacts.
The following instructions have been generalized to fit all
instruments. Detailed instructions for cam switch repair,
where required, will be found in the appropriate manual.
1. Remove any shields, switch shafts, interfering wires,
components, or circuit boards that prevent access to the
circuit board with the bad cam switch contact.
NOTE
Cam switch bearing blocks that attach to more than
one circuit board should not be separated from both
boards during disassembly, unless absolutely neces-
sary, as proper bearing alignment will be difficult.
2. Completely remove from the instrument the circuit
board having the defective cam switch contact.
3. To replace the defective cam switch contacts, follow
the instructions given in the switch repair kit.
4. To reassemble the instrument, reverse the disassem-
bly procedure.
B. PUSHBUTTON SWITCHES
The pushbutton switches are not repairable and should
be replaced as a unit if defective. Use a de-soldering tool to
remove solder from the holes in the circuit board when un-
soldering the switches.
Cathode-Ray Tube
The following procedure outlines the removal and re-
placement of the cathode-ray tube (crt).
1
W A R N I N G
)
Use care when handling a crt. Protective clothing and
safety glasses should be worn. A void striking it on any
object that might cause it to crack or implode. When
storing a crt, place it in a protective carton or set it
face down in a protected location on a smooth surface
with a soft mat under the faceplate to protect it from
scratches.
A. REMOVAL
1. Remove the bezel assembly, which is held in place
with two screws. (The bezel assembly incudes a snap-in
implosion shield.)
2. Disconnect deflection leads from crt neck pin recepta-
cles and disconnect the storage-element cable connector
from the Storage circuit board.
NOTE
The red and black wires entering the crt shield are
connected to the trace-rotation coil inside the shield.
They will not hamper crt removal and need not be
unsoldered.
3. Remove the crt base cover on the rear panel of the
instrument. Remove the crt base-pin socket.
4. Disconnect the crt anode plug from the jack located
on the panel adjacent to the left side of the crt shield.
Ground the crt anode plug to the chassis momentarily to
dissipate any stored charge.
5. With one hand on the crt faceplate, push on the crt
base, being sure to feed the storage-element cable and the
anode lead through the slot and hole in the bottom and rear
of the main portion of the crt shield as the crt slides forward.
Pull the crt out of the instrument from the front.
REV MAY 1982