Need response from a Castle tech for MMM question
 

I understand that my question will void the warranty, and I accept this. I've already modded mine so the warranty is void anyway.

With the failures of the Mamba Monster seemingly being attributed to the BEC circuit, is there a way to totally defeat the built-in BEC in favor of an external one? Just removing the red wire in the throttle cable only prevents the BEC from powering external devices (servos, Rx, etc), but still powers the internal circuits. And if the BEC goes bad, the ESC is dead. I know that you will eventually solve the problem and it will be as solid as the rest of your products, but in the meantime, I don't want to be forced to ship an ESC back and forth for repairs, not to mention the wait time in between.

What I want to do is open up the ESC, cut the trace at the input of the BEC circuit (effectively removing it from the circuit), and "inject" the voltage from an external BEC where the internal one's output is. Basically, turn it into an Opto ESC without true isolation from opto-coupling the throttle signal. FYI: I'll probaby be using the Koolflight UBEC, which is very stable and noise free.

I suspect you don't want such a method widely known, so I understand if you decline to answer. If I do not hear from you, I will start dissecting the circuit and figure it out on my own anyway, but was hoping to have a little help from the experts. :smile:

Thank you for your time.

I haven't heard of anyone's MMM dieing while running a external bec with the internal bec still connected, yet

I know, but I want to be SURE. :smile:

Brian, I dont think you have voided your warrantee by trimming the case. You only void it if you run without a fan. You dont need th top of the case to run a fan. I'd zip tie one on at least untill you are confident that the one you have isnt a dud. I know this would be very hard for the ulitmate hater of fanss to do, but to mee it seems prudent considering th situation.

Well, modded case or not, the mod to the BEC circuit will surely void it. And we'll see about the fan. If I can get a Quark to run cool passively, I think I can get the MMM to run just as cool if not better! But fan or no fan aside, I still want to make that BEC mod. Judging by reports, it will be a killer ESC if the BEC didn't fail.

At this point, NOTHING should void the warranty. People are trying to get the thing to work one way or the other. CC should seek feedback from the mod attempts and say "thanks."

Give Castle a call Monday morning. I called them yesterday about my MMMs and my need for a ESC by the 14th, and let's just say they went way beyond helpfull on coming up with something I can use until the MMMs are solid. Between what I've seen on the forums and what I got out of that phone call, I'd say Castle is willing to do whatever it takes to keep their customers happy. I'll bet they work with you on your idea to bypass the BEC. Their ph # is on their site.

My 2nd MMM just burned last night using the external ccbec, and the fan wired to the receiver. It ran good for a little while but once I got to the track and was warming up it went up in flames. :whistle:

If it went up in flames -- it wasn't a BEC failure. Most likely it was over current -- setup incorrect, and possibly demagged the motor. Every major failure like this that we have seen have been setup problems where the current rises from a damaged motor so quickly that the over-temp doesn't have a chance to kick in.

Patrick

So Patrick, how about the original question?

There's really no easy way to do it. You would need to remove multiple parts to isolate the circuits correctly. The input power to the BEC circuit comes from an internal plane with multiple vias and a poured copper plane on the top layer. There isn't any easy way to disconnect it.

You would need to remove the inductor, the switcher chip (MSOP-8) and the mosfets (the two TSOP-6 parts.)

Patrick

Mine burned. I put the Max back in and it is fine. Same motor, same connectors. The only difference is one is a MMM and one is a MM...and one works and one doesn't.

In that case, it could just have been a bad FET, it could have been a bad solder joint on a FET, or a solder joint could have cracked on a FET.

Send it in, we'll fix it up. :)

Patrick

OK, thanks for the response. I think I'm going to go this route just to ensure no BEC issues.

Patrick, to be totally clear, the components to remove are the ones in the pic below correct? This will completely disable the built-in BEC? I would;ve thought that just removing the coil would be enough...

http://scriptasylum.com/forumpics/mmm_bec_mod.jpg

I know I'll have to "inject" external 6v power into the MMM throttle power line so the internal circuits can have their power.