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Old 28th December 2005, 02:48 PM   #1
Netlist is offline Netlist  Belgium
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Default Unknown SMD

I found this broken SMD in a plotter board, in the regulator stage.
One side carries 40VDC, the other is connected to ground.
The fuse is broken as I measure a short across both leads of the device.
If you look carefully, you see a sign of a half sine wave and the letters M R. R might be B

As usual, any help is appreciated.

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Old 29th December 2005, 02:26 PM   #2
Onra is offline Onra  Germany
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it,s a SEMITRON device (now Littlefuse).
The marking code can be found at:
and should be a SMB40 unidirectional transient suppressor with a voltage limit of 40V.

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Old 29th December 2005, 04:58 PM   #3
Netlist is offline Netlist  Belgium
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thank you very much. Page bookmarked.

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Old 30th December 2005, 12:02 PM   #4
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These devices failsafe shorted
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