duet 2 wifi board 's U3 is easy broken , PPTC will have help?
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if V3.3 and gnd connection or other pin，it will die，so, if I have a breakout board ,and add a PPTC Resettable Fuse in the breakout board 3.3v , will have help?
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turning off the power when rewiring things and measuring the impedance between 3.3v and ground before turning on the power also solves the problem without additional hardware.
Fuse can help if it is fast enough. Series resistances to limit the current can help as well. Or if you have to replace U3 anyway try to find a replacement that has short circuit protection built in, will probaly cost more, but if you expect to frequently short out 3.3v it might be worth the effort to find one.
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The problem isn't that the regulator can't tolerate a short circuit, it can and often does (users frequently mis-wire the endstop switches). I think the problem is the transient created when short on the 3.3V rail is released. The shape and size of that transient depends on the wiring to the endstop switch. We're looking at adding transient suppressors on the newer boards.
