Blown Victors - WHY?

[DarkJedi613]

Originally Posted by wmurphy

Just curious - do you know the FET part #s and a good source for them? Thanks!

I do in fact - I just have to find it.

From DigiKey: IRL3103-ND
($1.64 ea., $1.16 per 10, $.96 per 100)

Mouser also has them (search for IRL3103)

Also we know for sure that we got metal shavings in when we blew them - we took them out when we took the Victor apart.

I'm going to attach a PDF spec sheets if you want to check it out yourself. (The Victor fet specs are too large to attach, but I'll email it to anyone who wants it.)

[Al Skierkiewicz]

Originally Posted by roboticsjenkins

They blew because you probably grounded the Victors out because I had that problem last year. It's better to mount them on a piece of material that is not a conductor of electricity......Thats my guess

Andrew,
The case of the Victors is an insulator. We mount our electricals on a punched aluminum sheet and have never had a problem.

"From DigiKey: IRL3103-ND"
It is really interesting if you take a look at the data sheet on these little gems. http://www.irf.com/product-info/data...ta/irl3103.pdf Note under maximum ratings, that continuous current is 64 amps and pulsed current is 220 amps per device (limited by junction temperature). Remember that there are three devices in parallel for 64 x 3=192 amps as long as you can keep the little buggers cool. When teams blow these up, there is some extreme abuse occuring. High currents over long periods of time, heat and/or metal flakes in of near the devices spell destruction. Changing FETs is not a guaranteed fix, other devices may be destroyed when a FET(s) short.
Please note that the Drain and the tab of the package are connected together. That means that the tabs of half of the FETs in the victor are connected to battery positive and the tabs of the other half are connected to motor positive. Keep conductive material away from the FETs.

[DarkJedi613]

Originally Posted by Al Skierkiewicz

Changing FETs is not a guaranteed fix, other devices may be destroyed when a FET(s) short.

Yeah, I know - if you blow the board its just gone (though you can save the muffin fan!).

One of our mentors created a tester to see what was wrong with the Victor, I'll see if I can get a wire diagram and pictures of it.

[Der Sichelmann]

Of the victors our team has blown, the problem has always been FETs. We have been able to repair them.