WARNING! A new way for MMMs to fail including your precious V3! - Page 3 - RC-Monster Forums

stum · 10.31.2008, 10:24 PM

Quote:

Originally Posted by JerryF504

Honestly, to me, it doesn't look like the problem was the bullet shorting to the heatsink. To me it looks more like there was excess resistance in that connector that caused the it to melt. I had some excess resistance in one of my bullets but I caught it in time because it was on the battery side and the symptoms were obvious. Being on the motor side I'm not sure how noticable the symptoms would have been. It looks like the biggest part of your bullet that is burned off isn't even on the side of bullet closest to the heasink.

Looking at it again I also agree w/ your assessment. I bet if that one was a sliding out it and only had a partial connection it would have done this as well.. give it a try it's pretty hairy.

PS RYU (from comment above), you are dead wrong.. take a look again, if you leave the MMM in the stock form and use the provided castle motor leads the heatshrink on the motor leads are resting firmly against the top plastic just over the exposed finned area, making it IMPOSSIBLE for the connector to hit unless the shrink wore off those wire leads. I have looked it over several times.. and thought it plenty through.

11.01.2008, 01:10 AM

You know the heat sink is not part of the elec circut in the esc. So if it did touch the connector nothing should happen. Also since it is alum it would have more blown out of it than the bullet if it was part of a short. I think the bullet connector was the problem here.

tc3_racer_001 · 11.01.2008, 06:16 PM

ive noticed spots on my battery connectors, where it seems like its been arcing to the female plug.... i really want a v1 which works!! lol. hope they fix this soon!

11.01.2008, 09:14 PM

I've noticed most male bullet connectors with casting flash on the edges. I always file the flashing off so you only get the flat part of the connectors touching.

BrianG · 11.01.2008, 10:41 PM

Quote:

Originally Posted by Desmo

You know the heat sink is not part of the elec circut in the esc. So if it did touch the connector nothing should happen. Also since it is alum it would have more blown out of it than the bullet if it was part of a short. I think the bullet connector was the problem here.

True, the HS is not part of the circuit, but it can act like a bridge if two bullet connectors touch it at the same time. But yeah, you'd think the HS would show more arc pitting than the bullet if that was the case.

Ryu James · 02:48 AM

Quote:

Originally Posted by stum

Looking at it again I also agree w/ your assessment. I bet if that one was a sliding out it and only had a partial connection it would have done this as well.. give it a try it's pretty hairy.

PS RYU (from comment above), you are dead wrong.. take a look again, if you leave the MMM in the stock form and use the provided castle motor leads the heatshrink on the motor leads are resting firmly against the top plastic just over the exposed finned area, making it IMPOSSIBLE for the connector to hit unless the shrink wore off those wire leads. I have looked it over several times.. and thought it plenty through.

....making it impossible for the MALE connector to touch but not impossible for the FEMALE connector to touch. the female connector is what i am referring to. or also the male portion that inserts in the female. (now i am sounding like sex ed.

) unless you heatshrink it, tape it, bend heatsink, it can/or already is touching. but that is besides the point now. you mentioned something that may be the answer. that if the male connector came out and was touching the female connector lightly that it could cause this short. is that correct? if so that is what i am thinking happened at this point. curious though? how does this cause a short just by lightly touching if it is still touching the right connector? also, should i change this connector? will it affect the performance? if the connector has the gold finish rubbed off does this also affect performance? here are some more pics to help us find the answer and help us see eye to eye.

my camera is not the best but you can see the heatshrink is fine. aside from that though look at the connector. it has a round shape zap in it like where it rested on top of the female plug on the esc. so i was thinking that it must have slipped out, bounced around, and touched the heatsink and female connector at the same time whilst one of the batt. famales on the esc is up against the heatsink also, causing the short. but if the light connection itself could have caused this that is likely the answer. any input on this? the last pic is of me holding a female end to the male end that shorted to show how the tip of the male connector has the indentation of the female connector on it. (whew! long winded explanation)

ps. sorry but for some reason i could only post links to the pics.

http://i471.photobucket.com/albums/r...s/DSC00482.jpg
http://i471.photobucket.com/albums/r...s/DSC00483.jpg
http://i471.photobucket.com/albums/r...s/DSC00484.jpg
http://i471.photobucket.com/albums/r...s/DSC00485.jpg
http://i471.photobucket.com/albums/r...s/DSC00486.jpg

kulangflow · 11.02.2008, 02:50 AM

J3110 · 11.02.2008, 07:00 AM

So, yeah, this whole not enough space for the heatshrink on your connectors thing kinda bugs me.
I don't like the amount of pressure there is between the heatsink and the shrink tubing on my motor wire bullets. There will be metal on metal contact there after only a few runs...at the very least, it is something to worry about.
So, what do I do? Just wait'l something goes wrong or send it back to them asking for one that leaves anough of a gap that I don't have to worry about these connectors shorting to the heatsink?

What the hell, Castle? Nowhere during your quality checking did anyone notice this might present an issue? I mean, why would anyone wanna put shrinkwrap on their connectors? Of course people will want all 3 motor leads making contact with the same aluminum heatsink...

Think I'll see what I can manage with a scap of lexan, but I'm really getting sick of the whole Castle mantra of "fix it yourself before using".

If I wanted it to be like this, I'd be buying caps, fets and circuitboards and making my own.

ravin · 11.02.2008, 10:15 AM

It looks to me like the male bullet was not pushed in all the way and it just overloaded the connection.

Pdelcast · 11:25 AM

Quote:

Originally Posted by J3110

So, yeah, this whole not enough space for the heatshrink on your connectors thing kinda bugs me.
I don't like the amount of pressure there is between the heatsink and the shrink tubing on my motor wire bullets. There will be metal on metal contact there after only a few runs...at the very least, it is something to worry about.
So, what do I do? Just wait'l something goes wrong or send it back to them asking for one that leaves anough of a gap that I don't have to worry about these connectors shorting to the heatsink?

What the hell, Castle? Nowhere during your quality checking did anyone notice this might present an issue? I mean, why would anyone wanna put shrinkwrap on their connectors? Of course people will want all 3 motor leads making contact with the same aluminum heatsink...

Think I'll see what I can manage with a scap of lexan, but I'm really getting sick of the whole Castle mantra of "fix it yourself before using".

If I wanted it to be like this, I'd be buying caps, fets and circuitboards and making my own.

Hmmmm --- Again, we checked, and checked and checked this issue--- OVER AND OVER AND OVER AGAIN. We shorted the bullets, scraped off the anozide and pushed the heatsink intot he bullets, etc. Never could we even get ONE failure to occur.

So don't berate us, we tested the hell out of this supposed "problem" and found there to not be a problem.

Besides -- I don't think the issue was a pair of bullets pushed into the heat sink -- or there would have been two bullets that showed damage. And the heat sink itself would have also have burn damage which isn't evident in the pictures. It could very well have just been a loose connector that caused that type of damage (as the male connector made poor contact, it burned the edges of the female.)

MrMin · 11.02.2008, 11:28 AM

Nice one Patrick. If you take a hammer to it, eventually everything will break.

I would actually cable-tie the wires down to the body so that no flex happens to the connection.

lutach · 11.02.2008, 11:32 AM

The male plugs should have a very snug fit when going into the female and any slop would cause such a failure. So everyone make sure your male plugs are somewhat hard to push into the female to prevent this from happening. If the male plug comes off easily, carefully spread the contacts apart a little to give you that very tight fitting.

Pdelcast · 11.02.2008, 11:35 AM

Quote:

Originally Posted by MrMin

Nice one Patrick. If you take a hammer to it, eventually everything will break.

I would actually cable-tie the wires down to the body so that no flex happens to the connection.

Yeah, well that's true. --

We've built about 4500 MMM V3s to date (on the machines) and finished and shipped about 1500 of 'em.

If we see failure rates above about 1%, I'll be very surprised (and I don't expect actual failure rates -- not user-induced failures -- to go above about 1/4%). We have not seen a single "It just died" BEC failure like we did on the V1 and V2, and we have yet to see a complete FET failure like we did on the V1 and V2 -- so I'm pretty confident that the V3 is going to prove to be fairly bulletproof.

auto2 · 11.02.2008, 11:41 AM

ive had bullets come apart on me on the motor side for no apparant reason. now i use long heat shrink so it covers the motor side also and put a wire tie around it.

Sparky · 11.02.2008, 11:49 AM

I very thankful Castle Creations has ventured out into the 1/8 scale ESCs. It just takes a while for people to find out the all the design issues. I’m sure Castle will come up with a solid design. I personally think the V1 design was better with the wires connected directly to the ESC. I also think any fan on an ESC is a bad design. The voltage should be increased until no fan is required.