Maintenance—492/492P Service Vol. 1 (SN B030000 & up)
CORRECTIVE MAINTENANCE
Corrective maintenance consists of component replace
ment and instrument repair. Special techniques and proce
dures required to replace components in this instrument are
described here.
Obtaining Replacement Parts
All electrical and mechanical parts are available through
your local Tektronix Field Office or representative. The Re
placeable Parts list section contains information on how to
order these replacement parts.
NOTE
Some components that are heat sinked to the circuit
board extrusion or module wall are soldered to the
board after the board is mounted in place. This is nec
essary to avoid cracking the IC case when the mount
ing screw is tightened. These components are
identified by a note on the schematic drawing. Their
part number appears with chassis mounted compo
nents in the Replaceable Electrical Parts list.
Parts orientation and lead dress should be duplicated be
cause some components are oriented to reduce interaction
or control circuit characteristics.
If a part you have ordered has been replaced with a new
or improved part, your local Field Office or representative
will contact you concerning any change in the part number.
After repair, the circuits may need recalibration.
Parts Repair and Return Program
Assemblies containing hybrid circuits or substrates in a
semi-sealed module, complex assemblies such as the YIG
oscillator, 829 MHz converter assembly, or phase gate de
tector can be returned to Tektronix for repair under the re
pair and return program. Contact your local Field Office for
exchange rates.
Tektronix repair centers provide replacement or repair
service on major assemblies as well as the unit. Return the
instrument or assembly to your local Field Office for this
service.
Soldering Techniques
Disconnect the instrument from its power source be
fore replacing or soldering components.
Some of the circuit boards in this instrument are
multilayer; therefore, extreme caution must be used when a
soldered component is removed or replaced. Excess heat
from the soldering iron and bent component leads may pull
the plating out of the hole. We suggest clipping the old com
ponent free. Leave enough lead length so the new compo
nent leads can be soldered in place. If you desire to remove
the component leads, use a 15 watt or less pencil type iron.
Straighten the leads on the back side of the board; then
when the solder melts, gently pull the soldered lead through
the hole. A desoldering tool should be used to remove the
old solder.
Replacing the Square Pin for the Multi-pin
Connectors
It is important not to damage or disturb the ferrule when
removing the old stub of a broken pin. The ferrule is pressed
into the circuit board and provides a base for soldering the
pin connector.
If the broken stub is long enough, grasp it with a pair of
needle nose pliers, apply heat with a small soldering iron to
the pin base of the ferrule, and pull the old pin out. (The pin
is pressed into the ferrule so a firm pull is required to pull it
out.)
If the broken stub is too short to grasp with pliers, use a
small dowel (0.028 inch in diameter) clamped in a vise to
push the pin out of the ferrule after the solder has been
heated.
The old ferrule can be cleaned by reheating the solder
and placing a sharp object such as a toothpick or small
dowel into the hole. A 0.031 inch drill mounted in a pin vise
may also be used to ream the solder out of the old ferrule.
REV AUG 1981
4-7
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