Sharp LC-20AV7U Service Manual - Page 5

Standard Notes For Servicing - manual

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STANDARD NOTES FOR SERVICING NOTE: CBA AND PWB MEANS PRINTED WIRING BOARD. Circuit Board Indications a. The output pin of the 3 pin Regulator ICs is indicated as shown. Top View Input Out In Bottom View Precautions for Using Lead-free Solder 1 Employing lead-free solder Pb free mark (as shown below) indicates lead-free solder, and is attached on the PWBs and service manuals. For PWBs with Pb free mark, be sure to use lead-free solder. For PWB without Pb free mark, use standard solder. The alphabetical character following Pb shows the type of lead-free solder. b. For other ICs, pin 1 and every fifth pin are indicated as shown. < Bottom View > 5 Pin 1 10 c. The 1st pin of every male connector is indicated as shown. < Bottom View > Pin 1 Instructions for Connectors 1. When you connect or disconnect the FFC (Flexible Foil Connector) cable, be sure to first disconnect the AC cord. 2. FFC (Flexible Foil Connector) cable should be inserted parallel into the connector, not at an angle. FFC Cable Connector CBA 2 Using lead-free wire solder When fixing the PWB soldered with the lead-free solder, apply lead-free wire solder. Repairing with conventional lead wire solder may cause damage or accident due to cracks. As the melting point of lead-free solder (Sn-Ag-Cu) is higher than the lead wire solder by 40°C, we recommend you to use a dedicated soldering bit, if you are not familiar with how to obtain lead-free wire solder or soldering bit, contact our service station or service branch in your area. 3 Soldering As the melting point of lead-free solder (Sn-Ag-Cu) is about 220°C which is higher than the conventional lead solder by 40°C, and as it has poor solder wettability, you may be apt to keep the soldering bit in contact with the PWB for extended period of time. However, Since the land may be peeled off or the maximum heat-resistance temperature of parts may be exceeded, remove the bit from the PWB as soon as you confirm the steady soldering condition. Lead-free solder contains more tin, and the end of the soldering bit may be easily corroded. Make sure to turn on and off the power of the bit as required. If a different type of solder stays on the tip of the soldering bit, it is alloyed with lead-free solder. Clean the bit after every use of it. When the tip of the soldering bit is blackened during use, file it with steel wool or fine sandpaper. Be careful when replacing parts with polarity indication on the PWB silk. * Be careful to avoid a short circuit. 3-1 LCV_NOTE

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3-1
LCV_NOTE
NOTE: CBA AND PWB MEANS PRINTED WIRING
BOARD.
Circuit Board Indications
a.
The output pin of the 3 pin Regulator ICs is indicated
as shown.
Top View
Out
In
Bottom View
Input
b.
For other ICs, pin 1 and every fifth pin are indicated
as shown.
5
10
Pin 1
< Bottom View >
c.
The 1st pin of every male connector is indicated as
shown.
Pin 1
< Bottom View >
Instructions for Connectors
1.
When you connect or disconnect the FFC (Flexible
Foil Connector) cable, be sure to first disconnect the
AC cord.
2.
FFC (Flexible Foil Connector) cable should be in-
serted parallel into the connector, not at an angle.
FFC Cable
Connector
CBA
* Be careful to avoid a short circuit.
Precautions for Using Lead-free Solder
1
Employing lead-free solder
Pb free mark (as shown below) indicates lead-free
solder, and is attached on the PWBs and service
manuals. For PWBs with Pb free mark, be sure to use
lead-free solder. For PWB without Pb free mark, use
standard solder. The alphabetical character following
Pb shows the type of lead-free solder.
2
Using lead-free wire solder
When fixing the PWB soldered with the lead-free solder,
apply lead-free wire solder. Repairing with conventional
lead wire solder may cause damage or accident due to
cracks.
As the melting point of lead-free solder (Sn-Ag-Cu) is
higher than the lead wire solder by 40°C, we recommend
you to use a dedicated soldering bit, if you are not
familiar with how to obtain lead-free wire solder or
soldering bit, contact our service station or service
branch in your area.
3
Soldering
As the melting point of lead-free solder (Sn-Ag-Cu) is
about 220°C which is higher than the conventional lead
solder by 40°C, and as it has poor solder wettability, you
may be apt to keep the soldering bit in contact with the
PWB for extended period of time. However, Since the
land may be peeled off or the maximum heat-resistance
temperature of parts may be exceeded, remove the bit
from the PWB as soon as you confirm the steady
soldering condition.
Lead-free solder contains more tin, and the end of the
soldering bit may be easily corroded. Make sure to turn
on and off the power of the bit as required.
If a different type of solder stays on the tip of the
soldering bit, it is alloyed with lead-free solder. Clean
the bit after every use of it.
When the tip of the soldering bit is blackened during
use, file it with steel wool or fine sandpaper.
Be careful when replacing parts with polarity indication
on the PWB silk.
STANDARD NOTES FOR SERVICING