PLC1/AVC5-UB
General Soldering GuidelinesRemoval
1. Use a grounded-tip, low-wattage soldering iron and1. Desolder and straighten each IC lead in one operation by
appropriate tip size and shape that will maintain tipgently prying up on the lead with the soldering iron tip as
temperature within the range 500!F to 600!F.the solder melts.
2. Use an appropriate gauge of resin-core solder composed2. Draw away the melted solder with an anti-static suction-
of 60 parts tin/40 parts lead.or with solder braid
removing the IC.
3. Keep the soldering iron tip clean and well-tinned.
Replacement
4. Thoroughly clean the surfaces to be soldered. Use a1. Carefully insert the replacement IC in the circuit board.
0.5 inch or 1.25 cm
handle. Do not use freon-propelled spray-on cleaners. 2. Carefully bend each IC lead against the circuit foil pad
and solder it.
5. Use the following desoldering technique.
a. Allow the soldering iron tip to reach normal3. Clean the soldered areas with a small wire-bristle brush.
500!F to 600!FIt is not necessary to reapply acrylic coating to areas.
b. Heat the component lead until the solder melts.OSmall-signal� Discrete Transistor Removal/Replacement
Quickly draw away the melted solder with an anti-1. Remove the defective transistor by clipping its leads as
static, suction-type solder removal device or withclose as possible to the component body.
solder braid.
CAUTION: Work quickly to avoid overheating the2. Bend into a OU� shape the end of each of the three leads
circuit board printed foil.remaining on the circuit board.
6. Use the following soldering technique.3. Bend into a OU� shape the replacement transistor leads.
a. Allow the soldering iron tip to reach normal
500!F to 600!F4. Connect the replacement transistor leads to the
corresponding leads extending from the circuit board and
b. First, hold the soldering iron tip and solder strandcrimp the OU� with long nose pliers to insure metal to
against the component lead until the solder melts.metal contact, then solder each connection.
c. Quickly move the soldering iron tip to the junction ofPower Output Transistor Devices Removal/Replacements
the component lead and the printed circuit foil, and1. Heat and remove all solder from around the transistor
hold it there only until the solder flows onto andleads.
around both the component lead and the foil.
CAUTION: Work quickly to avoid overheating the2. Remove the heatsink mounting screw (if so equipped).
circuit board printed foil or components.
3. Carefully remove the transistor from the circuit board.
d. Closely inspect the solder area and remove any
excess or splashed solder with a small wire-bristle4. Insert new transistor in circuit board.
brush.
5. Solder each transistor lead, and clip off excess lead.
6. Replace heatsink.
Diode Removal/Replacement
1. Remove defective diode by clipping its leads as close as
possible to diode body.
2. Bend the two remaining leads perpendicularly to the
circuit board.
Use Soldering Iron to Pry Leads3. Observing diode polarity, wrap each lead of the new
diode around the corresponding lead on the circuit board.
IC Removal/Replacement4. Securely crimp each connection and solder it.
Some Hitachi unitized chassis circuit boards have slotted
oblong5. Inspect (on the circuit board copper side) the solder joints
then bent flat against the circuit foil. When holes are theof the two Ooriginal leads�. If they are not shiny, reheat
slotted type, the following technique should be used tothem and, if necessary, apply additional solder.
remove and replace the IC. When working with boards using
the familiar round hole, use the standard technique as
outlined in paragraphs 5 and 6 above.
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ACEC
