Tektronix 2235A Instruction Manual page 105

Maintenance
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2235A Instruction
CLEANING. Loose dust on the outside of the instrument
can be removed with a soft cloth or small soft-bristle
brush. The brush is particularly useful for dislodging dirt
on and around the controls and connectors. Dirt that
remains can be removed with a soft cloth dampened in a
mild detergent-and-water solution. Do not use abrasive
cleaners. Clean the light filter and the crt face with a soft
lint-free cloth dampened with isopropyl alcohol,
denatured ethyl alcohol, or a mild detergent-and-water
solution.
INSPECTION. lnspect the internal portions of the instru-
ment for damage and wear, using Table 6-3 as a guide.
Deficiencies found should be repaired immediately. The
corrective procedure for most visible defects is obvious;
however, particular care must be taken if heat-damaged
components are found. Overheating usually indicates
other trouble in the instrument; therefore, it is important
that the cause of overheating be corrected to prevent
recurrence of the damage.
Interior
If any electrical component is replaced, conduct a
Performance Check for the affected circuit and for other
T o gain access to internal portions of the instrument for
closely related circuits (see Section 4). If repair or
inspection and cleaning, refer to the Removal and
replacement work is done on any of the power supplies,
Replacement Instructions in the Corrective Maintenance
conduct a complete Performance Check and, if so indi-
part of this section.
cated, an instrument readjustment (see Section 5).
Table 6-3
Internal Inspection Checklist
Scans by
ARTEK MEDIA
==+
Repair Action
Clean solder corrosion with an
eraser and flush with isopropyl
alcohol. Resolder defective con-
nections. Determine cause of
burned items and repair. Repair
defective circuit runs.
Replace defective resistors. Check
for cause of burned component
and repair as necessary.
Resolder joint and clean with
isopropyl alcohol.
Replace defective capacitors. Clean
solder connections and flush with
isopropyl alcohol.
Firmly seat loose semiconductors.
Remove devices having distorted
pins. Carefully straighten pins (as
required to fit the socket) using long-
nose pliers, and reinsert firmly.
Ensure that straightening action does
not crack pins, causing them to
break.
Firmly seat connectors. Repair or
replace defective wires or cables.
Straighten, repair, or replace
defective hardware.
Item
Circuit Boards
Resistors
Solder Connections
Capacitors
Semiconductors
Wiring and Cables
Chassis
Inspect For
Loose, broken, or corroded solder
connections. Burned circuit boards.
Burned, broken, or cracked
circuit-run plating.
Burned, cracked, broken, or
blistered.
Cold solder or rosin joints.
Damaged or leaking cases.
Corroded solder on leads or
terminals.
Loosely inserted in sockets. Distorted
pins.
Burned, broken, or frayed wiring.
Dents, deformations, and damaged
hardware.