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Unread 05-05-2005, 23:15
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Al Skierkiewicz Al Skierkiewicz is offline
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AKA: Big Al WFFA 2005
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Re: Victor Burnouts

Quote:
Originally Posted by Sparks333
Hey all!
Been awhile...
This is what I think happened with the hand-cranking the winch, and also it makes sense that only one set of FETs would blow out if you're only wheeling it one way, so the other direction should still work. Also, check the main capacitor in the middle. Another man I once met inspecting the Vics noticed some sticky stuff on one of his, and said it's electrolyte. I don't know how much truth there was to this, but if your capacitor's top is bulging, then it's gonna blow. Replace it before bad things happen.

Sparks

Oh, and Bob? That white stuff, I'd bet, is electrolyte.
Sparks,
I thought we lost you, glad to see you back. We have been back driving Victirs for years with out any ill effects. The motors do act as generators and there is enough leakage current that backs up through the controller to turn the LEDs on but unless you are pushing the robot at highway speeds in is unlikely you can genreate enough current to fry the controllers. The main cap in the middle of the FETs is rated pretty well for the voltage we use but where it is located subjects to very high heat when the robot is working hard, like during practice. The heat causes early failure and the case has a pressure relief that leaks the electrolyte out of the can. This is nasty stuff so don't touch and then put your finger in your mouth. When it has dried for several days, it does turn into a white, crusty almost lime looking (as in hard water deposit) gunk and it eats copper and other metals. The white smudges are really the result of the magic smoke leaving the device at high speed. They are mostly the ashes of the silicon interior that vaporized during the event. If everything looks normal except the white residue, know that a closer look will show a crack in the case. In some of the more spectacular deaths, there has been loud cracks followed by microscopic plastic shrapnel as the cases of the FETs blow apart.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.
 


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