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I'm doing a bit of reverse engineering on my Das Keyboard Model S Ultimate. I'm beginning to develop a pretty good understanding of the circuitry, but I am confused about one type of component on the board.

There are 4-5 components on this board with the reference designator of LB. This isn't a standard refdes that I'm aware of and I can't think of anything that I would label as LB. What might this component be? You can see one of them pictured here near the smaller connector.

Picture of board with unidentified component

Description: They look to be about the same size as an 0805 capacitor but gray instead of that brownish color of a cap. It isn't as dark as a resistor either.

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  • \$\begingroup\$ Any chance that is "FB"? Ferrite Bead? \$\endgroup\$ – Dwayne Reid Apr 14 '15 at 22:55
  • \$\begingroup\$ Measure the DC resistance. \$\endgroup\$ – Dwayne Reid Apr 14 '15 at 22:55
  • \$\begingroup\$ It appears to be LB not FB, and unfortunately my multimeter is currently out of commission. \$\endgroup\$ – Michael Leonard Apr 14 '15 at 23:07
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It is likely a ferrite bead. The lb would stand for inductor bead. Looking at the board it may be a filter on the small connector's power or ground pin.

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  • \$\begingroup\$ Yes that appears to be the case. They are placed near all of the connectors that carry power as well as on the output of the only on-board LDO. Can't imagine why they'd use LB rather than FB but oh well. Thanks! \$\endgroup\$ – Michael Leonard Apr 15 '15 at 0:06
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    \$\begingroup\$ @MichaelLeonard Well, L would be the normal ref des for an inductor, so it makes sense. \$\endgroup\$ – Roger Rowland Apr 15 '15 at 3:59

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