Tektronix CURVE-TRACER 576 Instruction Manual page 93

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NOTE
The rear mounting bracket will bend outward
allowing enough clearance to remove assembly.
Disassembling the Cam Switch Assornbly.
1. Remove the cam switch assembly as doscribed pre-
viously.
2. Romovo the two screws from the top of tho metal
::;over and remove the cover.
3. Separate the cam from the circuit board by removinCJ
the four connecting screws from the circuit board.
4.
The cam may be disconnected from its support
blocks by removing the retaining ring from the shaft on the
front of the switch and sliding the cam out of the support
block. Be careful not to lose the small detent roller.
5. Defective switch contacts may be replaced by first
unsoldering the damaged contacts and cleaning the solder
from the holes in the circuit board. Next, position the new
contacts in the holes so they are properly aligned in relation
to the other switch contacts and the mating area on the
circuit board (an alignment tool is provided in the cam
switch repair kit). Solder the new contacts into place. Be
sure that the spring ends of the contacts have adequate
clearance from the circuit board.
6.
Reassemble the cam switch assembly by reversing the
previous process.
Replacement of a Cam Switch Assembly.
1. Connect the switch to the front panel.
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Maintenance-Type 576
2. Connect tho circuit board to the rear mounting
bracket.
NOTE
Do not bend the circuit board while securing it to the
rear mounting bracket. If the circuit board must be
bent to secure the board to the rear mounting
bracket, re-adjust the rear mounting bracket.
3. Reconnect the pin connections to the proper pins
(see Figs. 4-6 through 4-28).
Rotary Switches. Individual wafers or mechanical parts
of rotary switches are normally not replaceable. If a switch
is defective, replace the entire assembly. Replacement
switches can be ordered either wired or unwired; refer to
the Electrical Parts List for the applicable part number.
When replacing a switch, tag the leads and switch termi-
nals with corresponding identification tags as the leads are
disconnected. Then, use the old switch as a guide for
installing the new one. An alternative method is to draw a
sketch of the switch layout and record the wire color at
each terminal. When soldering to the new switch, be careful
that the solder does not flow beyond the rivets of the
switch terminals. Spring tension of the switch contact can
be destroyed by excessive solder.
Semiconductor Replacement_ Semiconductors should
not be replaced unless they are actually defective. If re-
moved from their sockets during routine maintenance,
return them to their original sockets. Unnecessary replace-
ment or exchange of semiconductors may affect the calibra-
tion of this instrument. When semiconductors are replaced,
check the operation of that part of the instrument which
may be affected.
CAUTION
POWER switch must be turned off before removing
or replacing transistors.
Replacement semiconductors should be of tho original
type or a direct replacement. Fig. 4-2 shows the lead con-
figuration of the semiconductors used in this instrument.
Some plastic case transistors have lead configurations which
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