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Maintenance
6–6
TDS 684A, TDS 744A, & TDS 784A Service Manual
CAUTION. To prevent damage from electrical arcing, ensure that circuit boards
and components are dry before applying power to the oscilloscope.
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 failed module and
replace 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 damaged module and
replace 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
straightening 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, and dam-
aged hardware.
Straighten, repair, or replace
defective hardware.
Cleaning Procedure — Interior.
To clean the oscilloscope interior, do the following:
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.)