TO 1-1-700 - Robins Air Force Base

TO 1-1-700
8.6.3 Cleaning Procedures/Selection Criteria. Always
select the mildest method of cleaning that will accomplish the
task. Circuit components can be damaged if cleaned using the
wrong support equipment. The method used shall be based on:
a. Type and severity of the contamination or corrosion.
b. Accessibility of the contamination or corrosion.
c. Type of electronic equipment.
8.6.3.1 Hazards of Cleaning. Always use the gentlest
materials and cleaning methods that will ensure complete
cleaning or corrosion removal. In addition, always use the
correct cleaning solutions mixed to the proper concentrations.
Substitutions are not permitted. Using incorrect equipment, or
solutions in high concentrations can result in damage to electronic
components.
8.6.3.1.1 Solvent entrapment - solvents, detergents, or water
may become trapped in crevices or cavities. This will interfere
with additional cleaning or refinishing operations. In addition,
it can prevent correct operation of the electronic equipment
after the repair is complete.
c. Ensure that drain and vent holes are open.
d. Remove covers, doors, etc.
e. Disassemble or remove from enclosures if practical and
necessary for the required cleaning.
f. Verify the availability of authorized cleaning materials.
g. Double-check the compatibility of cleaning materials
before use.
h. Mask vulnerable components to prevent the entrance of
water, solvents, or detergents.
8.6.3.4 Cleaning and Drying Restrictions. Some circuit
components are vulnerable to damage during the cleaning process.
Usually, the potential for this damage can be minimized
prior to cleaning. The biggest contributing factor to this damage
is water or solvent trapped by a component. Vulnerable
components and techniques to minimize their vulnerabilities
are shown in Table 8-6. Procedures for sealing components are
as follows:
8.6.3.1.2 Over scrubbing - prolonged abrasive scrubbing can
cause delamination in printed circuit boards.
8.6.3.1.3 Solvent attack - certain solvents can soften conformal
coatings, wire insulation, acrylics, and some circuit components.
Do not substitute solvents in the cleaning process.
8.6.3.2 When to Clean. Immediate cleaning shall occur
whenever any of the following conditions exist:
8.6.3.2.1 Electronics have been exposed to adverse weather
or salt-water spray.
8.6.3.2.2 Electronics have been exposed to fire-extinguishing
agents.
8.6.3.2.3 Batteries have discharged electrolyte solution on or
near electronic components.
8.6.3.2.4 Repair is necessary because of corrosion or component
failure.
8.6.3.3 Precleaning Treatment. Accomplish the following
before starting a cleaning operation:
a. Disconnect any external power supply from electronics.
TT-I-735, ALCOHOL, ISOPROPYL 65
a. Seal small components with SAE-AMS-T-21595, Pressure
Sensitive Tape. Ensure tape and tape residue are
removed using Solvent Cleaning followed by wiping
with TT-I-735 Isopropyl Alcohol prior to drying the
equipment.
b. Seal large components in plastic bags or seal with MIL-
PRF-131 Water Vapor Proof Barrier Material. Place the
bag or barrier material around the component and seal
with SAE-AMS-T-21595 Pressure Sensitive Tape.
Ensure tape, tape residue, and bag or barrier materials
are removed using Solvent Cleaning followed by wiping
with TT-I-735 Isopropyl Alcohol prior to drying the
component.
c. In some cases the component may be removed from the
equipment without too much difficulty. When this is
possible, the removed component shall be cleaned separately.
This method is preferred for any component that
can be easily removed.
b. Remove batteries.
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