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View Full Version : shorting feet on steering fets for different chassis'


stuZ
2006.11.09, 06:31 PM
does anyone have any experience or knowledge about which fet feet to leave 'unshorted' for the steering fets on various boards for various chassis'?

I ask because I am converting an mr02 board for use in an ma-010.
I have noticed that the innermost feet of the steering fet are left unshorted
on the ma-010 stock board. On an mr-01 board I have, I think that they are the legs furthest to the left.

anyway, does any one have any knowledge on this issue?

Spoon
2006.11.09, 07:25 PM
does anyone have any experience or knowledge about which fet feet to leave 'unshorted' for the steering fets on various boards for various chassis'?

I ask because I am converting an mr02 board for use in an ma-010.
I have noticed that the innermost feet of the steering fet are left unshorted
on the ma-010 stock board. On an mr-01 board I have, I think that they are the legs furthest to the left.

anyway, does any one have any knowledge on this issue?


I don't have an answer for you but it's easier if you talk in terms of pin numbers.

The "top" of the FET is the side where the dimple ior dot is. That usually denotes pin1. Fromm there the pins are numbered counter clockwise...like this

1 8
2 7
3 6
4 5

As far as I know pins 5,6,7 & 8 are all shorted together on every board.

stuZ
2006.11.09, 07:33 PM
As far as I know pins 5,6,7 & 8 are all shorted together on every board.

thanks spoon,
As far as I know that is just for the drive motor side of the board, not the steering motor.
so, 5,6,7,8 are output?

I'll have to take some pictures.

pomme de terre
2006.11.09, 08:57 PM
Im 99% sure its the same with the steering. I have mine all shorted on that side and my steerings fine

Spoon
2006.11.09, 10:12 PM
thanks spoon,
As far as I know that is just for the drive motor side of the board, not the steering motor.
so, 5,6,7,8 are output?

I'll have to take some pictures.
Now I understand what you are asking...I have seen what you ar etalking about...with the three of the pins connected but not the forth. I didn't understand at first.

I have a Mini-Z apart now...I'll look at it.

LBRC
2006.11.09, 11:13 PM
As long as pin 6 and 7 are connected they are all internally connected. Pins 6 and 5 are the P channel output 7 and 8 are the N channel output, for the servo motor to turn clockwise it takes the P channel form one mosfet and the N channel from the other mosfet, to turn counterclockwise it uses the other two P and N channel pairs.

In other words the wires must be connected to all 4 pins but to do this all you have to do is solder them to the middle pair. %10,000,000 positive :p

stuZ
2006.11.10, 11:09 AM
thank you guys, that is great, I pulled apart a couple of cars last night and found different configurations, all with the center two (at least) always soldered together.
What might make a steering fet burn out when powering up the chassis?

imxlr8ed
2006.11.10, 04:49 PM
Not saying it's right to do... but I do have an F1 with all the legs on the output side of each fet soldered together, and it works just fine. (all four feet to one wire)

LBRC
2006.11.10, 10:40 PM
...What might make a steering fet burn out when powering up the chassis?

Itís exceedingly hard to toast a steering FET on a Mini-Z, for example if you stop and hold the servo motor itís likely to burn the motor before damaging the FETs. To actually toast one of the FETs the chief suspect would be some sort of short, for example a direct short across the outputs bypassing the motor, or better yet a short to ground.