MAINTENANCE
8.8 HANDLING AND CLEANING
PRECAUTIONS
When troubleshooting or otherwise working inside the in-
strument, care should be taken not to indiscriminately
touch PC board traces and open wires to avoid con-
taminating them with body oils or other foreign matter.
In particular, there are two areas within the Model 263 that
have high impedance devices or sensitive circuitry where
contamination could cause degraded performance. These
include the shielded area on the analog board and shielded
area on the mother board.
The same general precautions apply when replacing parts
in these amas. When unsoldering and soldering parts, be
careful not to spread the flux around the board to adja-
cent areas.
1. Using a squeeze bottle, carefully apply clean, uncontami-
nated methanol to the area to be cleaned. Use sufficient
solution to thoroughly wet the circuit board.
2. Using a small, clean brush, wipe the area thoroughly
until it is free of flux or contaminants. In some cases,
it may be helpful to tilt the board at an angle and brush
contaminants away fmm the affected area, allowing con-
taminated residue and methanol to run off the board.
3. Wash the area again with fresh, clean methanol, allow-
ing it to drain, flushing contaminants off the board.
4. Once the area is thoroughly cleaned, it should be dried
with pressurized dry clean air or nitrogen. Do not use
compressed air from an ordinary air compressor, as oil
particles in the ait could contaminate the circuit board.
5. After cleaning or parts replacement check to see that ary
components connected to the Teflon insulators are not
physically touching the board or adjacent parts.
h.
1
WAVEFORM
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8-22
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