Hitachi 42EDT41A Service Manual page 7

NOTE: These components are affixed with glue. Be careful not to break or damage any foil under the
component or at the pins of the ICs when removing. Usually applying heat to the component for a short time
while twisting with tweezers will break the component loose.
Leadless Chip Components
(surface mount)
Chip components must be replaced with identical chips
due to critical foil track spacing. There are no holes in the
board to mount standard transistors or diodes. Some chip
capacitor or resistor board solder pads may have holes
through the board, however the hole diameter limits
standard resistor replacement to 1/8 watt. Standard
capacitors may also be limited for the same reason. It is
recommended that identical chip components be used. .
Chip resistors have a three digit numerical resistance code
-1st and 2nd significant digits and a multiplier. Example:
162 = 1600 or 1.6KΩ resistor, 0 = 0Ω (jumper).
Chip capacitors generally do not have the value indicated
on the capacitor. The color of the component indicates the
general range of the capacitance.
Chip transistors are identified by a two letter code. The first
letter indicates the type and the second letter, the grade of
transistor.
Chip diodes have a two letter identification code as per the
code chart and are a dual diode pack with either
common anode or common cathode. Check the parts list
for correct diode number.
Component Removal
1. Use solder wick to remove solder from component end
caps or terminals.
2. Without pulling up, carefully twist the component with
tweezers to break the adhesive.
3. Do not reuse removed leadless or chip components
since they are subject to stress fracture during
removal .
Chip Component Installation
1. Put a small amount of solder on the board soldering
pads.
2. Hold the chip component against the soldering pads
with tweezers or with a miniature alligator clip and
apply heat to the pad area with a 30 watt iron until
solder flows. Do not apply heat for more than 3
seconds
Chip Components
TYPE
C
GRADE
B
TRANSISTOR
E
COMMON CATHODE
ANODES
MH DIODE
TABLE OF CONTENTS
SOLDER
CAPS
CAPACITOR
1ST DIGIT
2ND DIGIT
MULTIPLIER
= 1600 = 1.6K
SOLDER CAPS
RESISTOR
How to Replace Flat-lC
—Required Tools—
• Soldering iron
• De-solder braids
1. Remove the solder from all of the pins of a Flat-lC by
using a de-solder braid.
Flat-IC
2. Put the iron wire under the pins of the Flat-lC and pull
it in the direction indicated while heating the pins using
a soldering iron. A small awl can be used instead of
the iron wire.
Soldering
Pull
Iron
3. Remove the solder from all of the pads of the Fiat-
lC by using
a de-solder braid.
4. Position the new Flat-lC in place (apply the pins of the
Flat-lC to the soldering pads where the pins need to be
soldered). Properly determine
the positions of the soldering
pads and pins by correctly
aligning the polarity symbol.
5. Solder all pins to the soldering pads using a fine tipped
soldering iron.
Solder
6. Check with a magnifier for solder bridge between the
pins or for dry joint between pins and soldering pads. To
remove a solder bridge, use a de-solder braid as shown in
the figure below.
Bridge
Solder
7
PW1A
• iron wire or small awl
• Magnifier
De-Solder
Braid
Soldering
Iron
Iron
Wire
Awl
Soldering
Iron
Soldering
Iron
De-Solder
Braid
Flat-IC
Polarity Symbol
Soldering
Iron
De-Solder
Braid
Soldering
Iron