When soldering on circuit boards or small insulated
wires, use only a 15-watt, pencil-type soldering iron. A
higher wattage soldering iron may cause etched circuit
conductors to separate from the board base material and
melt the insulation on small wires. Always keep the
soldering-iron tip properly tinned to ensure best heat
transfer from the iron tip to the solder joint. Apply only
enough solder to make a firm joint. After soldering,clean
the area around the solder connection with an approved
flux-removingsolvent (such as isopropyl alcohol)and allow
it to air dry.
Use rosin-core wire solder containing 63% tin and 37%
lead. Contact your local Tektronix Field Office or repre-
sentative to obtain the namesof approvedsolder types.
To avoid an electric-shock hazard, observe the fol-
lowing precautions before attempting any soldering:
turn the instrument off, disconnect it from the ac
power source, and wait at least three minutes for
the line-rectifierfilter capacitors to discharge.
WARNING
I
The reliability and accuracy of this instrument can be
maintainedonly if proper solderingtechniquesare used to
remove or replace parts. General soldering techniques,
which apply to maintenance of any precision electronic
equipment, should be used when working on this instru-
ment.
SOLDERING TECHNIQUES
To remove a soldered DIP IC when it is going to be
replaced, clip all the leads of the device and remove the
leads from the circuit board one at a time. If the device
must be removed intact for possible reinstallation, do not
heat adjacentconductorsconsecutively.Apply heat to pins
at alternate sides and ends of the IC as solder is removed.
Allow a moment for the circuit board to cool before
proceedingto the next pin.
To remove socketed dual-in-line packaged (DIP)
integrated circuits, pull slowly and evenly on both ends of
the device. Avoid disengaging one end of the integrated
circuit from the socket before the other, since this may
damagethe pins.
The chassis-mounted power supply transistor is insu-
lated from the chassis by a heat-transferring mounting
block. Reinstall the mounting block and bushings when
replacing these transistors. Use a thin layer of heat-
transferring compound between the insulating block and
chassis when reinstallingthe block.
6-14
After replacing a power transistor, check that the
col/ector is not shorted to the chassis before apply-
ing power to the instrument.
Any replacement component should be of the original
type or a direct replacement. Bend transistor leads to fit
their circuit board holes, and cut the leads to the same
length as the original component. See Figure 9-2 in the
"Diagrams" section for lead-configurationillustrations.
Transistors and integrated circuits should not
be
replaced unless they are actually defective. If removed
from their sockets or unsoldered from the circuit board
during routine maintenance, return them to their original
board locations. Unnecessaryreplacementor transposing
of semiconductordevicesmay affect the adjustment of the
instrument. When a semiconductor is replaced,check the
performanceof any circuit that may be affected.
TRANSISTORS AND
INTEGRATED CIRCUITS
Multipin Connectors
When pin connectors are grouped together and
mounted in a plastic holder, they are removed,reinstalled,
or replacedas a unit. If any individualwire or connector in
the assemblyis faulty, the entire cable assemblyshould
be
replaced.To provide correct orientation of a multipin con-
nector, an index arrow is stamped on the circuit board,
and either a matching arrow is moldedinto or the numeral
1 is marked on the plastic housing as a matching index.
Be sure these index marks are aligned with each other
when the multipinconnectoris reinstalled.
End-Lead Pin Connectors
Pin connectors used to connect the wires to the inter-
connect pins are factory assembled. They consist of
machine-insertedpin connectors mounted in plastic hold-
ers. If the connectors are faulty, the entire wire assembly
should be replaced.
Interconnectionsin this instrument are made with pins
soldered onto the circuit boards. Several types of mating
connectors are used for the interconnectingpins. The fol-
lowing information provides the replacement procedures
for the varioustypes of connectors.
INTERCONNECTIONS
Maintenance-2430 Service
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