Need response from a Castle tech for MMM question

[BrianG]

AFAIK, you are the fourth one to do this mod. One user (brushlessboy) attempted and did something a little wrong. Another (TruckBasher) did it and it worked for a time, but eventually went south again (no idea why). Hopefully yours lasts a while, and if not, hopefully CC will honor the warranty.

[George16]

Originally Posted by lincpimp

Well, I did the Bec removal mod and my dead V2 is alive again...

Hope it lasts! I will bash it extra hard. I am trying to run the truck hard to break any weak points, including the electronics. I will say that the hacker 11xl on 6s will easily launch the lst 2 feet in the air and flip it 2 or 3 times from a standing start... Way too much power, just like I like it. Plus the motor stays around 150f. I may step to a 1521, but I am not sure if it will make much difference.

Good to hear that.

Anyway, are you using a UBEC or Rx pack?

I talked to a rep from CC last night (I have to call at least almost midnight due to time difference) and asked about doing the BrianG mod.

So anyway, I'll be doing Brian's mod but instead of a UBEC(just ordered Dimension Engineering's Sport BEC), I'll be using one of my 6V rx packs from nitro revo. If it doesn't work, I will be shipping a dead MMM to CC and wait a couple of weeks for the replacement ESC to arrive unless Lutach's 10S Chineses ESC arrives first.

[BrianG]

You actually said "the BrianG" mod? They're gonna hate me when I decide to stop by someday...

[George16]

Originally Posted by BrianG

You actually said "the BrianG" mod? They're gonna hate me when I decide to stop by someday...

Yes I did . Hopefully they'll give you something as a token of gratitude .

[lincpimp]

Originally Posted by George16

Good to hear that.

Anyway, are you using a UBEC or Rx pack?

I talked to a rep from CC last night (I have to call at least almost midnight due to time difference) and asked about doing the BrianG mod.

So anyway, I'll be doing Brian's mod but instead of a UBEC(just ordered Dimension Engineering's Sport BEC), I'll be using one of my 6V rx packs from nitro revo. If it doesn't work, I will be shipping a dead MMM to CC and wait a couple of weeks for the replacement ESC to arrive unless Lutach's 10S Chineses ESC arrives first.

I decided to use a rec pack, as i really do not feel like soldering up anything right now! I may invest in a novak regulator and use a 2s lipo pack, but atm I will be using a IB nimh pack...

[kulangflow]

Originally Posted by BrianG

AFAIK, you are the fourth one to do this mod. One user (brushlessboy) attempted and did something a little wrong. Another (TruckBasher) did it and it worked for a time, but eventually went south again (no idea why). Hopefully yours lasts a while, and if not, hopefully CC will honor the warranty.

Technically, I was the fourth, but it didn't work for me. Bleh.

[George16]

Originally Posted by lincpimp

I decided to use a rec pack, as i really do not feel like soldering up anything right now! I may invest in a novak regulator and use a 2s lipo pack, but atm I will be using a IB nimh pack...

Did you disconnect the red wire from the ESC?

[TruckBasher]

Lito, no need to remove it...its for back feeding the MMM

Brian, just curious if USB can back feed brains while the switch is off/batts disconnected do you think we can back feed the MMM brain without your mod but leave the switch off?

BTW i got my 2nd MMM but not sure if I want to mod it cause the first one is already out of warranty and I dont want another junk.....I sure hope we can find solution to this mess

[BrianG]

Not sure what backfeeding the ESC while keeping the BEC intact will do. Depending on exactly what is bad (and how), it could basically short the external BECs voltage (which would send the external BEC into a cycling shutdown condition).

Back during my first mod, I was using an external BEC and didn't remove the red wire at first. Well, the KF voltage was ~6v, but the MMM BEC was ~5.5v and the KF heated up quite a bit. That tells me right there that the MMMBEC was heavily loading the external BEC because of the higher external voltage. So, even when everything is working normally, using an external BEC AND the internal one at the same time doesn't work.

[Arct1k]

This is what I think killed BrushlessBoy16's MMM as he did this for a while and even Brian's chip removal mod failed to revive the controller.

[George16]

Originally Posted by BrianG

Not sure what backfeeding the ESC while keeping the BEC intact will do. Depending on exactly what is bad (and how), it could basically short the external BECs voltage (which would send the external BEC into a cycling shutdown condition).

Back during my first mod, I was using an external BEC and didn't remove the red wire at first. Well, the KF voltage was ~6v, but the MMM BEC was ~5.5v and the KF heated up quite a bit. That tells me right there that the MMMBEC was heavily loading the external BEC because of the higher external voltage. So, even when everything is working normally, using an external BEC AND the internal one at the same time doesn't work.

I did the mod and it didn't work. It let off a small puff of smoke after I plug the rx pack (the red wire was not removed) and lipos. The rx pack is 5-cell hump pack from one of my nitro trucks. It was also hot. I'm not sure if the lipo or rx pack caused the smoke .

So anyway, it's officially dead. That's my first V2 to die.

Back to the waiting game again

[BrianG]

You must have accidentally bridged a solder pad or two - easy to do when they are so small. Do you know what blew?

[George16]

Originally Posted by BrianG

You must have accidentally bridged a solder pad or two - easy to do when they are so small. Do you know what blew?

I don't know the part name but here's a pic. Both are circled in red.

[joeling]

Those look like SMD capacitors

Regards,
Joe Ling

[BrianG]

Yeah, and I wonder if you had the BEC leads reversed (switched the + and -)? That's the only thing I can think of that would blow a cap, that and overvoltage.