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View Full Version : Fets on mr03 sport, leaving existing fets


mmakam2
2014.11.07, 09:09 PM
hello all,

Can I stack fets on top of the stock fets?

I feel this is less risky if this is OK to do.

Also, can I replace fets on a MR03VE?

THANKS IN ADVANCE

abasualdo
2014.11.10, 11:54 AM
The MR03S boards have two open spots for adding two more fets. You could just add two 3010s or 8858 fets in those spots. As far as mixing fets, I don't know, never tried it myself. On my MR03S board, I removed the two stock fets and replaced them with two 3010s and added two more 3010s on the open spots on the other side of board.

I know people(even world class mini-z racers) used to stack upgrade fets on top of the original fets, with good results. Thats why I think you could get away with mixing fets.

As far as the VE board, yes it can be fetted, but stock works fine. I fried the stock fets on my VE board after shorting it out, used the PN fets, board work great again.


Because the PN and 8858 fets are interchangeable, I will fet my next VE board with 8858 as they are alot cheaper and should work fine.

Al

mmakam2
2014.11.10, 02:27 PM
So if I threw two 8858CZ fets on the stock fets, and two more on the open pads, I should be good?

abasualdo
2014.11.10, 03:34 PM
I think it should work(never tried it), not ideal, but should work.

Btw, easiest way to remove fets without a hot air smt rework station(cheap ones can be had for around $125) is to use the double edge razor technique. Videos can be found on YouTube, don't have a direct link.

Basically, you break the razor into a small piece no wider than the fet itself. You slide it under the fet, heat up the fet legs and slide out the razor between the board pads and fet legs. Never force the fet off or you run the risk of lifting or worst yet, tearing a board pad off.

NoBrainer
2014.11.10, 05:45 PM
I would remove the stock FET's.
You would never know what kind of throttle curve you would get with mismatch of FET's.

8858 is cheap and I would rather remove the stock and put 4 pcs of 8858 on there and have a great car.

cowboysir
2014.11.11, 11:25 AM
If I recall correctly, Reflex Racing built a competitive chassis by layering one set of 8858 on the standard ASF 3010's. I don't see why you couldn't do it in a Sports chassis.

abasualdo
2014.11.11, 12:07 PM
+1 - That was the example I was thinking of.

NoBrainer
2014.11.12, 05:39 AM
I do believe you can stack them.
But the different FET's have different linear response.
Maybe you won't be able to tell or maybe you like the way the car handles afterwards, I don't know.
But with the same type of FET's all around you will be guarantied the same response.

dameetz
2014.11.12, 09:45 AM
As far as the VE board, yes it can be fetted, but stock works fine. I fried the stock fets on my VE board after shorting it out, used the PN fets, board work great again.


Because the PN and 8858 fets are interchangeable, I will fet my next VE board with 8858 as they are alot cheaper and should work fine.

Al

Is there any difference after you changed the fet on the VE board?

abasualdo
2014.11.12, 10:14 AM
Didn't have enough time on the stock VE board before I shorted it out.
Don't really know how much of a difference it made.

According to Phil from PN, his own guys fet the VE boards because his fets have a more linear feel, compared to stock or the 8858.

I have to say my repaired, PN fetted VE board does feel very nice, but alot of that may have to do with my ASF settings, motor, batteries and gearing.

I plan on fetting my next VE board with 8858s to compare the two.

mmakam2
2014.11.13, 10:33 PM
Is fetting on a VE not necessary because brushless motors don't pull enough amps to fry the stock fets??

What kind of mod motors would be significantly more powerful than the stock ECO tune in my JSCC MR-03VE?

abasualdo
2014.11.14, 07:47 AM
Most guys run the VE boards without fetting them.

To my knowledge, the Eco motor is the most mild mini-z brushless motor right now. It's kv is around 4500kv(1000 rpm per volt) - 5000 according to info.

It's a great motor, especially for smaller tracks or clubs looking to build a spec brushless class.

Faster than a 70t, but not at a 50t level.

I run the PN green 5500 and just started testing the PN grey 7500(gen 1 motors). I run on smallish to medium-large size tracks, those motors work for me.

I have a PN gold 9500, don't run it, too fast, may test it again in the future. :D

btw, at our last big GTG at Railyard, the winning car in open mod(anything goes) was running a PN 5500, aaa batteries, 53/13 gearing

mmakam2
2014.11.18, 10:27 PM
What kind of solder do you guys use?

KWT
2014.11.19, 08:03 PM
I use the standard 40/60 tin/lead solder.