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Unread 07-03-2011, 13:21
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AKA: Phil Malone
FRC #1629 (GaCo: The Garrett Coalition)
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Re: [FTC]: Samantha? Like it or hate it?

I diagnosed a related issue last night.

An intermittant Network connection issues was traced back to an intermittant power connection at the Sami module.

Turned out NOT to be the module, but the plug-in cable/connector combo.

On closer inspection the red wire seemed stressed at the entry point to the white plastic connector, and slight wire jiggling could cause the Sami to reset.

The Sami module was tested on a spare power cable (where the heck did that come from ??????) and was proven to be robust. So we replaced the cable. All was good.

We disected the "stressed" part of the suspect wire, and found NO broken conductors. We can only assume that a prior incident had caused the actual metal barrel of the power plug to become deformed (spread) enough that wire movement caused intermittant connections with the mating part inside the Sami module. VERY hard to diagnose, but causes problems whenver the robot took a hard bump.

Once again, this is a VERY rough and tumble environment and teams MUST be educated on how to tie down cables and protect connectors. I'm still amazed to see how many NXT's and Batteries fall out during a match.

As an aside... I can't imagine LEGO ever assumed that the NXT USB cable connector would see the wear and tear that FTC is now forcing it to endure. Multiple plug/unplug cycles during code testing, then it becomes a CRITICAL link for the actual competition. This is probably a $0.50 part.

Seriously !!!

Phil.
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Phil Malone
Garrett Engineering And Robotics Society (GEARS) founder.
http://www.GEARSinc.org

FRC1629 Mentor, FTC2818 Coach, FTC4240 Mentor, FLL NeXTGEN Mentor
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