Maintenance
6-6
TDS 420A, TDS 430A & TDS 460A Service Manual
Table 6- 3: Internal Inspection Check List
Item Inspect For Repair Action
Circuit boards Loose, broken, or corroded
solder connections. Burned
circuit boards. Burned, broken, or
cracked circuit-run plating.
Remove failed module and
replace with a fresh module.
Resistors Burned, cracked, broken, blis-
tered condition.
Remove the module with the
faulty resistor and replace it with
a fresh module.
Solder connections Cold solder or rosin joints. Resolder joint and clean with
isopropyl alcohol.
Capacitors Damaged or leaking cases.
Corroded solder on leads or
terminals.
Remove the module with the
faulty capacitor and replace it
with a fresh module from the
factory.
Semiconductors Loosely inserted in sockets.
Distorted pins.
Firmly seat loose semiconduc-
tors. Remove devices that have
distorted pins. Carefully straight-
en pins (as required to fit the
socket), using long-nose pliers,
and reinsert firmly. Ensure that
straight ening action does not
crack pins, causing them to
break off.
Wiring and cables Loose plugs or connectors.
Burned, broken, or frayed wiring.
Firmly seat connectors. Repair or
replace modules with defective
wires or cables.
Chassis Dents, deformations. Straighten, repair, or replace
chassis.
Cleaning Procedure — Interior. Use the following procedure to clean the interior
of the oscilloscope.
STOP. If, after doing steps 1 and 2, a module is clean upon inspection, skip the
remaining s teps.
1. Blow off dust with dry, low-pressure, deionized air (approximately 9 psi).
2. Remove any remaining dust with a lint free cloth dampened in isopropyl
alcohol (75% solution) and rinse with warm deionized water. (A
cotton-tipped applicator is useful for cleaning in narrow spaces and on circuit
boards.)
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