Saturday, November 12, 2016

Replacing a Burnt Out MOSFET in an AR6400

This is a quick post about changing the MOSFET in an AR6400. This appears to be a a fairly common problem people have with RC airplanes such as the Hobbyzone Champ or the Parkzone P51 Mustang. Symptoms include elevator or other control surface only moving in one direction,  elevator or other control surface not moving at all, or a distinct electronics burning smell emanating from the control board. This appears to be usually caused by plugging in the battery backwards.

My AR6400L with MOSFET Desoldered

I don't really have a whole lot in the way of new information on the subject. I am just going to compile some of the necessary resources here for reference.

The replacement part is the FDG6322C. When I considered shipping, the cheapest place I could find in a short search was DigiKey. I would buy extras. They are extremely tiny. Here is the datasheet.
https://www.fairchildsemi.com/datasheets/FD/FDG6322C.pdf

One useful piece of information is that the two sides are wired the same, so if one is still intact you can use that side as reference. Here is a schematic taken from an rcgroups forum post that I found helpful.

Photo Credit: RCgroups.com member greghol

Here are the forum posts I used for reference. Really, the only pieces of information I would say you will need is the schematic and part number above.

https://www.rcgroups.com/forums/showthread.php?t=960011&page=3

https://www.rcgroups.com/forums/showthread.php?t=1221866#post14761707

https://www.rcgroups.com/forums/showthread.php?t=1837318

One last word of encouragement. I was able to do this with a pretty standard Weller SPG40 soldering iron. My burnt out MOSFET actually disentegrated while I was trying to remove it, but after replacing it the board works fine. It will fly again.

Notes:
At the time of this writing, these are some prices if you can't fix it.

  •  AR6400L - $60 (Ebay)
  • Hobbyzone Champ - $89.99 (Your local hobby shop)
  • HobbyKing SuperMicro control board - $22.68 (HobbyKing)

-Matthew

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