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View Full Version : Steering FET blown - Replacement Question


PridgeoK
2008.04.16, 01:13 PM
One of my F1's managed to fry a steering FET last night while I was trying to put a transponder on it - full on flame happening for a couple seconds there! :eek: Luckily the body wasn't on it when this happened, but ya - nasty.

It's good timing that I received some 3010 FETs from Pinoyboy just the other day (thanks again, Pinoyboy! :D). He's mentioned that they should be fine to replace the 3004's that are stock on the board, so I'm going to try it out. Before I do so I wanted to ask a few questions for the FET guys here on the boards:

- the 4562's at the shop here are similar cost to the 3010's ($0.20 extra?). I was considering getting some extra FETs for possible future mishaps, and possibly for stacking on the MR-02's I have. Would the 4562 FETs be fine to use for steering FET replacements as well?

- Would upgraded steering FETs improve (increase) the steering rate? If so, could this conceivably be a bad thing - over steer?

Thanks,

Kevin.

PridgeoK
2008.04.17, 02:37 PM
Fix, fix... remove old fried 3004 FET and its pair... throw on the 3010's and solder 'em to the little pads which thankfully were still there. Test... turns right, turns left, still goes forward & backwards... okay... looks good... put the transponder back on, fit it on nice just like on the atomicmods site displays, and :eek: FRY! :eek: ...Yup - another FET up in smoke.

So ya - my transponder shorted out the corner FET. I didn't realize that's what made it go the first time, and now that it fried again, and left obvious charing on the bottom of the transponder... I've realized the error of my ways for the transponder location.

The lap-counter I have is an I-Lap counter and the F1 transponders are the same size as the giro-z's (16mm square). Doing the minor mod to the F1 chassis, the transponder has a slight overlap with the steering FETs and covers maybe 1/2 of the FET withe the edge of the transponder. This is pretty much the best spot for it so the infrared transmitter piece is sort of mid-driver.

I guess I should have glued on a hard thin plastic shell around the transponder maybe... but instead I think I've found a better location for it. I've now slightly modified the front bumper/wing protector and have it underneath there, similar to where I"ve seen the F1 core transponders sitting. To get the power cable back under the car body caused yet another bit of body modification, but it doesn't look horrible (not too disfigured, anyway). Hopefully it will be a good enough spot, but only time will tell (haven't set up the track and given it a go yet, so I don't know).

Anyway - back to the FET thing - I replaced the second burned FET with yet another 3010 and got it going again. The pads under the corner-most FET where the black cable connects are completely gone now. They were part & parcel with the burned FET, I found out. Since that side of the FET can be fully soldered together to that black wire, it still works though (whew! :rolleyes:)

I'm still wondering about the 4562's though - just want to get a feeling whether they'd be fine to paste on for steering FETs as well if this kind of thing ever happens again?

Kev.

PridgeoK
2008.04.17, 02:39 PM
Oh - just for the record - the F1 transponder still works fine after it's incident on top of the fried FETs. It's lasted through two car-fires now - directly underneath it too, so I'm pretty happy about its durability! LOL! I tested it again though, and it seems to be working just fine.

Kev.