Tektronix 5441 Instruction Manual page 95

3. Lift the circuit board out of the unit. Do not force or
bend the board.
4. To replace the board, reverse the order of removal.
Use care when replacing pin connectors; if forced into place
incorrectly, the pin connectors may be damaged.
Circuit-board Pins
C A U T I O N
a
Most circuit boards in this instrument are multi-layer
type boards with a conductive path@) laminated be-
tween the top and bottom board layers. All soldering
on these boards should be done with extreme care to
prevent breaking the connection to the center conduc-
tor(~); only experienced maintenance personnel
should attempt repair of these boards.
A circuit-board pin replacement kit including the neces-
sary tools, instructions, and replacement pins is available
from Tektronix, Inc. Order from your local Tektronix Field
Office or representative. Replcement of circuit-board pins on
multi-layer boards is not recommended; refer such repairs
to your local Tektronix Field Office or representative.
Semiconductors
C A U T I O N
a
To avoid component damage, power must be turned
off before removing or replacing semiconductors.
Semiconductors should not be replaced unless actually
defective. If semiconductors are removed during routine
maintenance, return them to their original sockets. Unnec-
essary replacement of semiconductors may affect the ad-
justment of this instrument. When semiconductors are
replaced, check the operation of that part of the instrument
that may be affected.
Handle silicone grease with care. Avoid getting sili-
cone grease in eyes. Wash hands thoroughly after
use.
Replacement devices should be of the original type or a
direct replacement. Figure 5-2 shows the lead configura-
tions of the semiconductor devices used in this instrument.
Some plastic-case transistors have lead configurations that
do not agree with those shown here. When replacing, check
the manufacturer's basing diagram for correct basing. All
transistor sockets in this instrument are wired for the stan-
dard basing used for metal-case transistors. Semiconduc-
tors that have heat radiators use silicone grease to increase
heat transfer. Replace the silicone grease with replacing
these semiconductors.
An extraction tool should be used to remove the 14- and
16-pin integrated circuits to prevent damage to the pins.
This tool is available from Tektronix, Inc. If an extraction
tool is not available when removing one of these integrated
circuits, pull slowly and evenly on both ends of the device.
Try to avoid having one end of the integrated circuit disen-
gage from the socket before the other, as the pins may be
damaged.
To replace one of the power transistors mounted on the
chassis adjacent to the Power Supply circuit board, first un-
solder the leads. Then, loosen the nuts on the plastic bar, or
the screw in the metal clamp, that clamps the transistor to
the chassis. Remove the defective transistor. When replac-
ing the transistor, use silicone grease on both sides of the
insulator plate and on the metal tab, if the transistor has
one, to increase heat transfer from the transistor to the
chassis.
Interconnecting Pin Replacement. To replace a pin that
is mounted on a circuit board, first disconnect any pin con-
nectors. Then, unsolder the damaged pin and pull it out of
the board with a pair of pliers. Be careful not to damage the
wiring on the board with too much heat. Ream out the hole
in the circuit board with a 0.031-inch drill. Remove the fer-
rule from the new interconnecting pin and press the new pin
into the hole in the circuit board. Position the pin in the same
manner as the old pin. If the old pin was bent at an angle to
mate with a connector, bend the new pin to match the asso-
ciated pins.
Switches
Two types of switches are used in this instrument. Con-
tact alignment and spacing are critical to the operation of
the pushbutton and cam switches. Therefore, defective
switches should either be replaced as a unit or repaired only
by personnel experienced with these types of switches.
Your local Tektronix Field Office or representative can pro-
vide additional information. The following special mainte-
nance information is provided for switch replacement.
REV MAY 1982