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rocketdogbert

AA-12 MOSFET ?

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Guys,

 

In need of some help, the FET in my AA-12 has blown (nasty, blackened do-dah on the board).

 

Anybody got a source for a replacement? I’m pretty sure I can put any one of a number of standard FETs in it, but I’d like to try source a TM one first

 

nON4uqm.jpg

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Yep, spoke to them, TM won’t sell the FET to them separately, and the whole gearbox is over £400 lol

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Not sure how much this will help you, but you may be able to find the manufacturer from it!

 

If not have you thought about just replacing the burnt out components, I know your techy, a solder pump, solder iron and new components should provide you with a challenge for the next few weeks.;)

image.png

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Lol, I’ve pulled the FET, it has TM stamped all over it, and the nasty burnt out lump.

 

If I could find a circuit diagram, I’d happily have a go at replacing the component, as I can’t make it any worse :D 

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Have you got a couple more photos of the  FET? Components wise? And by any chance was it caused by using a slightly more powerful battery than TM recommend?

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I’m out at the moment, could take some easily later.

No idea what caused it, guy who sold it to me swears it was working when he shippied it, no reason to doubt him.

I connected a 7.4 Lipo, bang goes the fuse.

I thought it was the motor, as it turned very slowly and heated the battery up if directly connected to the other two motor terminals, but a new motor and no difference meant digging deeper, and finding the FET problem.

I believe the FET prevents the gun from doing anything if a high voltage battery is connected, but the inter web is a bit vague on that.

The SGR-12 deffo has the feature.

The manual says it has protection from reverse polarity, and the FET led that is supposed to show a fault code doesn’t light up at all lol.

 

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Can't you just rewire it to say a Gate MOSFET?

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6 minutes ago, Chris_B said:

Can't you just rewire it to say a Gate MOSFET?

 

Yes, I can re-wire it with any sort of FET, but I’d like to keep it original if I can, cheers

 

John

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As with repairing any OEM products John, sometimes you might have to find an alternative as the cost to get a replacement original is uneconomical. But I totally get ya, it would be preferable to get an original part but I rekon you're gonna be chasing a wild goose with it trying to source one.

 

Have you checked the polarity of the battery that you used?

 

To me that melted component looks like an SMD (surface mound device) capacitor. God knows what value it is now and what other sensitive components the 'bang' has taken out.

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I used buyee to get hold of a gen TM FET from Yahoo Japan, hopefully it will work lol

Delivery due Tuesday

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