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Maintenance
c. Clean cartridge receiver using a tissue dampened with
alcohol.
d. Clean exposed areas of casting using a tissue dampened
with alcohol.
e. Replace the cartridge receiver and disc drive top cover.
f.
Restore the disc drive to operational status.
5·23.
REPAIR INFORMATION.
5-24.
The etched printed-circuit assemblies (PCA's) used
in Hewlett-Packard equipment are the plated-through type
consisting of metal bonded to both sides of an insulating
material. The metallic conductors are extended through the
component holes by a plating process. Soldering can be
performed on either side of the PCA with equally good
results. Table 5-3 lists recommeneded tools and materials
for use in repairing etched PCA's. Following are recom-
mendations and precautions pertinent to PCA repair work.
a. Avoid unnecessary component substitution; damage to
the PCA and/or adjacent components can result.
b. Do not use a high-power soldering iron on PCA's.
Excessive heat might lift a conductor or damage the
board.
I
CAUTION
I
Do not use a sharp metal object such as
an awl or twist drill to remove solder.
Sharp objects might damage the plated-
through conductor.
7901A
c. Use a suction device (refer to table 5-3) or wooden
toothpick to remove solder from component mounting
holes.
d. After soldering, remove excess flux from the solder
areas.
5-25.
The following procedures are recommended when
component replacement is necessary:
Note:
Although not recommended when both
sides of the PCA are accessible, axial lead
components such as resistors and tubular
capacitors
can
be
replaced without
unsoldering. Clip leads near body of
defective component, remove component
and straighten leads left in board. Wrap
leads of replacement component one tum
around original leads. Solder wrapped
connection and clip off excess lead.
a. Remove defective component from board.
b.
If
component was unsoldered, remove solder from
mounting holes with a suction device (refer table 5-3)
or a wooden toothpick.
c. Shape leads of replacement component to match
mounting hole spacing.
d. Insert component leads into mounting holes and
position component as original was positioned. Do not
force leads into mounting holes; sharp lead ends might
damage the plated-through conductor.
Table 5-3. Printed-Circuit Assembly Repair Equipment
ITEM
USE
OESCR IPTION
RECOMMENDED MODEL
Soldering Tool
Soldering and unsoldering
Wattage rati ng: 47 -1/2 to 56-1 /2W
Ungar #776 Handle with
Tip Temp: 850
0
to 900
0
F
Ungar #4037 Heating Unit*
Soldering Tip *
Soldering and unsoldering
Shape: pointed
Ungar#PL111*
Suction Device
Removes molten solder
Soldapullt by Edsyn Co., Arleta,
from connection
California
Resin (Flux)
Removes excess flux
Must not dissolve etched circuit
Freon
Solvent
from soldered area
base board material or conductor
Aceton
bonding agent
Lacquer Thinner
Isopropyl Alcohol (100% dry)
Solder
Component replacement,
Resin (flux) core, high tin content
printed-circuit board re-
(60/40 tin/lead). 18 gauge (AWG)
pair, and wiring connec-
preferred
tions.
*For working on etched boards; for general purpose work, use Ungar #1237 Heating Unit (37.5W, tip temp of 750
0
to
800°F) and Ungar #PLl13 1/8-inch chisel tip.
5·6
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