Tektronix CURVE-TRACER 576 Instruction Manual page 92

Maintenance-Type 576
be removed either by removing the guard box cover or
through the bottom of the instrument. If for some reason it
is necessary to remove the guard box, use the following
procedure:
1. Remove the right side panel from the Type 576.
2. Disconnect the MAX PEAK VOLTS-MAX PEAK
POWER WATTS switch assembly as follows:
a. Set the MAX PEAK VOLTS indicator to 15 and
the SERIES RESISTORS indicator to .3.
b. Looking behind the front panel, loosen the Allen
screw which can be seen through the hole in the front of
the front coupler half (see Fig. 4-4).
c. Set the SERIES RESISTORS indicator to 650 and
loosen another Allen screw which now appears through
the hole in the coupler half.
d. Pull the top portion of the switch assembly out
through the front panel.
e. Loosen the two Allen screws in the spacer sleeve.
f. Loosen the Allen screw in the end of the front
coupler half.
g. Pull the bottom portion of the switch assembly
through the front panel.
3.
Disconnect the LOOPING COMPENSATION shaft
from the coupler to the guard box by loosening the two
Allen screws in the coupler.
4. Disconnect P300 from the guard box.
5. Turn the Type 576 on its side and remove its bottom
cover.
6. Remove the screws from the chassis which hold the
iJUard box in place.
7. Carefully pull the guard box out of the instrument (it
is very heavy). The MODE switch coupling should discon-
nect as the guard box is removed.
To replace the guard box, reverse the preceding pro-
cedure.
Circuit Board Replacement. Most of the components
mounted on the circuit boards can be replaced without
removing the boards from the instrument. Observe the
soldering precautions given under Soldering Techniques in
this section. If a circuit board is damaged beyond repair,
either the entire assembly (including all soldered-on-
·components) or the board only can be replaced. Part num-
bers are given in the Mechanical Parts List for either the
completely wired board assembly or the unwired board.
Use the following procedure to remove a circuit board.
1a. To lift the board for maintenance or access to areas
beneath the board, disconnect the pin connectors which
might impair lifting.
4-12
1 b. To completely remove the board disconnect all the
remaining pin connectors.
2. Remove all screws holding the board to the chassis.
3. Lift the circuit board partially or all the way out of
the instrument. Do not force or bend the board.
4. To replace the board, reverse the order of removal.
The correct connections of the pin connectors is shown in
Figs. 4-6 through 4-28. Reconnect the pin connectors care-
fully so they mate correctly with the pins. If forced into
place incorrectly, the pin connectors may be damaged.
Cam Switches. A complete cam switch is actually a cam
switch assembly. Each assembly consists of a nylon cam
which is rotated by a front panel knob, and a set of con-
tacts mounted on an adjacent circuit board which are
actuated by the lobes on the cam. A cam switch repair kit
including the proper repair tools, instructions and replace-
ment contacts is available from Tektronix, Inc. (Tektronix
Part No. 040-0541-00).
CAUTION
Repair of cam switches should be undertaken only by
experienced maintenance personnel. The switch align-
ment and spring tension of the contacts must be care-
fully maintained for proper operation of the switch.
For assistance in the maintenance of cam switches,
contact your local Tektronix Field Office or rep-
resentative.
Removal of a Cam Switch Assembly.
1 a. To remove the cam switch assembly for main-
tenance or access to areas beneath, disconnect only those
pin connectors which might impair lifting.
lb. To completely remove the assembly disconnect all
the pin connectors.
2. Disconnect the switch from the front panel.
3. Disconnect the circuit board from the rear mount·
ing bracket.
NOTE
The thin film resistors on some of the cam switch
assemblies are brittle. Do not bend them when
handling.
4. Remove the switch assembly from the instrument.
©I
I
'-'I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
~
I
I