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2019/01/30 02:46:26 (GMT+09:00)
1-7. How to Find a Good Earth Ground
1)A cold-water pipe is a guaranteed earth ground; the cover-plate
retaining screw on most AC outlet boxes is also at earth ground.
2)If the retaining screw is to be used as your earth ground, verify that it is
at ground by measuring the resistance between it and a cold-water pipe
with an ohmmeter. The reading should be zero ohms.
3)If a cold-water pipe is not accessible, connect a 60- to 100-watt trouble-
light (not a neon lamp) between the hot side of the receptacle and the
retaining screw. Try both slots, if necessary, to locate the hot side on the
line; the lamp should light at normal brilliance if the screw is at ground
potential (see Figure 3).
1-8. Lead Free Information
The circuit boards used in these models have been processed using
Lead Free Solder. The boards are identified by the LF logo located
close to the board designation.
Figure 4: LF Logo
Figure 3. Checking for earth
ground.
Figure 5: LF logo on circuit board
The servicing of these boards requires special precautions. It is
strongly recommended to use Lead Free Solder material in order to
guarantee optimal quality of new solder joints.
12
SYS SET
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