Loose hardware, burned components, broken
c o n n e c t i o n s , and bent or broken pins on
Polyurethane materials are flammable and toxic. Do
assemblies and subassemblies
not smoke or permit sparks or open flames in the work
area. The work area must be well vented. Wear eye
You can clean the assemblies and subassemblies by
wiping them with a dry cloth or brush. Use a water
protectors, protective clothing, and polyethylene or
soluble detergent to clean the air falters on control
rubber gloves while working with the materials. Wash
consoles. For general cleaning of the consoles, use a
hands and exposed skin areas thoroughly with soap and
general cleaning solvent. To remove corrosion and
hot water after handling.
oxidation from the aluminum surfaces of the consoles,
Exercise care and observe the following
use trichlorotriflouroethane. Remember to observe all
precautionary measures during the handling and repair
safety precautions when using cleaning solvents.
of circuit cards. These measures will help you to prevent
further damage to the circuit cards and the replacement
1. Ensure all leads of removed parts are tagged.
Dangerous voltages exist in control consoles.
2. Make sure all hardware removed is replaced in
Observe all safety precautions before performing any of
the proper order.
the scheduled preventive maintenance.
3. Observe the polarity of the capacitors and
4 . Observe the placement and height of the
When you replace a part, remember that the new
part must be electrically and physically identical to the
defective part. Identification of repair parts is given in
integrated circuits is 18 watts maximum (tip temperature
the parts listing of the technical manual.
between 450° and 550°F) and for other parts is 25 watts
maximum (tip temperature between 750° and 850°F).
Unless otherwise specified in the detail repair
6. Ensure that the leads of the replaced parts are
repairing the control consoles:
trimmed flush on the back of the circuit card.
1. Remove and disassemble parts only to the extent
7. Avoid accidental touching of the soldering iron
necessary to inspect, clean, or replace a defective part.
or other heated instruments to the wire insulation.
2. When removing attaching hardware, note the
number and arrangement of hardware at each attaching
point. Be sure to replace hardware properly when
reassembling the item removed.
Do not touch integrated circuits with your bare
3. Inspect all removed parts as specified in the
hands because of possible damage by static electricity.
technical manual. Install only parts that are serviceable.
The hand tools you use must be properly grounded.
4. Check to be sure that mating parts are properly
engaged and aligned before tightening the mounting
Replacement of Assemblies
Repair of circuit cards will, in most instances,
After performing repair work, you must replace the
consist of removal and replacement of detail parts. In
assemblies or subassemblies. Instructions for replacing
some instances, however, the PCBs may be defective.
a s s e m b l i e s or subassemblies are listed in the
You can make practical repairs of defective (open)
m a n u f a c t u r e r ' s technical manual. In most cases,
printed conductors by installing jumper wires across the
replacement is the reverse of removal. Whenever special
open circuit. Upon completion of any circuit card repair
instructions are necessary, they are given in the technical
operation, calibrate and retest the circuit card. After
manual. After replacing the assemblies, thoroughly
calibration and retesting, apply a polyurethane coating
check out the repair and replacement.
to the reworked areas.