HT-SB250 (serv.man2) - Sharp Audio Service Manual (repair manual). Page 2

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HT-SB250
 – i –
PRECAUTIONS FOR USING LEAD-FREE SOLDER
1. Employing lead-free solder
Example:
Indicates lead-free solder of tin, silver and copper.
Lead-free wire solder for servicing
Ref No.
Description
Parts No.
"MAIN, POWER, AMPLIFIER, SWITCH PWB" of this model employs lead-free solder. The LF symbol indicates 
lead-free solder, and is attached on the PWB and service manuals. The alphabetical character following LF 
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 wet ability, 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 of for 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 corrected. 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 sand paper.
Be careful when replacing parts with polarity indication on the PWB silk.
PWB-A 92LPWB8091MANS 
MAIN (A1) / POWER (A2) / AMPLIFIER (A3) / SWITCH (A4)
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