Tektronix 543B, Instruction Manual

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Maintenance — Type 543B/RM543B
Standard Parts
Many of the components in this instrument are standard
electronic parts that can be purchased locally. However,
all parts in the instrument can be obtained through your
Tektronix Field Engineer or representative. Before Purchas­
ing or ordering parts, check the parts list in Section 6 to
determine the value, tolerance and rating required.
Special Parts
Some of the parts in the instrument are manufactured or
selected by Tektronix to meet specific requirements, or are
manufactured
for Tektronix to our specifications. These parts
and most mechanical parts should be ordered through your
Tektronix Field Engineer or representative. See "Parts
Ordering Information " and "Special Notes and Symbols"
in Section 6.
Tubes and Transistors
Tubes or transistors should not be replaced unless they
are actually defective. If tubes or transistors are removed
and found to be acceptable, be sure to return them to their
original sockets. Tube- or transistor-tester checks on the
tubes or transistors used in the Type 543B are not recom­
mended. Testers may indicate a tube or transistor to be
defective when it is operating satisfactorily in a circuit, or
may fail to indicate tube or transistor defects which affect
the performance of the circuit. It is recommended that tubes
and transistors be checked by substitution. If the tube or
transistor is good, return it to its socket. Unnecessary re­
placement of tubes or transistors is not only expensive but
may also result in needless recalibration of the instrument.
Wafer Switches
Individual wafers of switch assemblies are normally not
replaced. Replacement switches may be ordered from
Tektronix either wired
or unwired; see the parts list for the
part numbers.
Cathode-Ray Tube
To remove and replace the cathode-ray tube, use the
following procedure:
WARNING
Be careful when handling a crt. Avoid striking
it on any object that might cause it to crack and
implode. Flying glass from an imploding crt can
cause serious injury. Use safety glasses or a plas­
tic face mask for protection.
1. Remove crt bezel nuts, bezel and plastic light filter or
crt protector plate (see Fig. 4-2).
2. Remove plastic eyebrow and retaining spring from the
top of the crt (see Fig. 4-3).
3. Remove crt anode lead, disconnect all leads from the
neck of the crt except the crt trace-rotation coil leads.
4. Using a Phillips screwdriver, loosen crt base clamp (see
Fig. 4-4) so that the crt base is loose in the base clamp.
5. With a chisel-tipped plastic or wooden dowel, care­
fully work the crt socket loose from the crt base.
6. Grasp the face of the crt with the right hand. Push the
crt carefully towards the front of the instrument with the
left hand. Be careful not to bend the neck pins. Remove
the crt through the front of the oscilloscope.
7. Before reinstalling the crt, dust talcum power on the crt
base. This prevents the base of the crt from sticking
to the neoprene bushing inside the base clamp.
8. Carefully insert the new tube into the shield and the
tube base clamp. Keep the anode button in line with
the anode connector hole so that the button is aligned
with the hole when the crt is fully inserted.
9. Reconnect the crt socket to the tube base.
10. Turn the crt so that the horizontal graticule lines are
parallel with the top of the front panel.
NOTE
If the crt face is not aligned with the front of the
oscilloscope, use a hexagonal wrench to
loosen the two socket-head mounting screws that
fasten the base clamp to the mounting bracket
(see Fig. 4-4). Move the base clamp and crt
radially to align the face of the crt with the front
panel of the instrument.
11. Install eyebrow and eyebrow retainer spring. Position
the crt so that the front surfaces of the light pipe and
eyebrow are flush.
12. Tighten the base clamp.
4-3
Fia. 4-3. Crt bezel and eyebrow arrangement.