Panasonic CT-20SL15 - 20" CRT TV Manual de servicio - Página 4
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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 Component
(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
chips 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
capacitor may also be limited for the same reason. It is
recommended that identical components be used.
Chip resistor has a three digit numerical resistance code -
1st and 2nd significant digits and a multiplier.
Example: 162 = 1600 or 1.6k
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 terminal.
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
GRADE
C
B
E
TRANSISTOR
COMMON
CATHODE
ANODES
MH DIODE
Service Notes
resistor, 0 = 0
SOLDER
CAPS
CAPACITOR
1ST DIGIT
2ND DIGIT
MULTIPLIER
=1600 = 1.6k
SOLDER
CAPS
RESISTOR
How to Replace Flat-IC
- Required Tools -
Soldering iron
Needle nose pliers
Wire cutters (sharp & small)
1.
Cut the pins of a defective IC with wire cutters.
Remove IC from board. If IC is glued to the board,
heat the IC and release the IC. See Note above.
(jumper).
2.
Using soldering iron and needle nose pliers remove
the IC pins from the board.
3.
Using de-soldering braid and soldering iron remove
solder from affected are on board (pads).
4.
Position the new Flat-IC in place (apply the pins of
the Flat-IC to the soldering pads where the pins
need to be soldered). Determine the positions of
the soldering pads and pins by correctly aligning
the polarity symbol. Solder pin #1 first, align the IC.
Polarity
symbol
Solder the pin opposite to pin #1. This will assist
positioning the IC.
5.
Solder all pins to the soldering pads using a fine
tipped soldering iron.
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.
Solder
Bridge
A2-2
De-solder braids
Magnifier
Flat IC
2nd solder
Soldering
Solder
Iron
De-Solder
Braid
Soldering
Iron
De-soldering
Braid
Soldering
Iron
1st solder
Soldering
lron