Chip Parts Replacement - Mitsubishi HS-U748 Service Manual

CHIP PARTS REPLACEMENT

CHIP PARTS REPLACEMENT
Some resistors, shorting jumpers (0Ω resistor), ceramic
capacitors, transistors and diodes are chip parts.
When replacing these parts, note the following cautions.
Cautions :
A. Use fine tipped, well insulated soldering pencil (iron),
about 30 watts, and tweezers.
B. Melt the solder and remove the Chip Parts carefully
not to tear off the copper foil of the printed circuit
board.
C. Discard removed chips ; do not reuse them.
D. Do not apply heat for more than 3 seconds to new
Chip Parts.
E. Avoid using a rubbing stroke when soldering.
F. Take care not to scratch, or damage the Chip Parts
when soldering.
G. Supplementary cementing is not required.
1. Removal of Chip Parts
(Resistors, capacitors, etc.)
A. Grasp the part with tweezers. Melt the solder at both
sides alternately, remove one side of the part with a
twisting motion.
B. Melt the solder at the other side and remove the part.
Chip
Solder
Soldering Pencil
Pattern
Tweezers
Fig. 1
2. Removal of Chip Parts (Transistors)
A. Melt the solder of one lead. Lift the side of that lead
upward.
B. Simultaneously melt the solder of the two remaining
leads and lift the part from the PCB.
Chip
3. Replacement
A. Presolder the contact points of the circuit pattern.
B. Press the part downward with tweezers and apply the
soldering pencil as shown in Fig. 3.
Solder
Pattern
Tweezers
Chip
- 9 -
Lead
Pattern
Soldering Pencil
Tweezers
Chip
Pattern
PCB
Fig. 2
Soldering Pencil
PCB
Soldering Pencil
Fig. 3