Need response from a Castle tech for MMM question

[slimthelineman]

do you think castle would do this mod for a fee? i would like to avoid the internal bec completely if thats all it takes. even if i use an ubec without the mod then the bec will still be running all the time just with no load, so its only a matter of time until...

Originally Posted by slimthelineman

do you think castle would do this mod for a fee? i would like to avoid the internal bec completely if thats all it takes. even if i use an ubec without the mod then the bec will still be running all the time just with no load, so its only a matter of time until...

LOL....i was just thinking the same exact thing ....or wondering what kind of shop i could take this to to have it done ,as long as i know what exactly needs done ...cause i know there's no way i could do it ....LOL....maybe there's someone on here that would like to make a little extra cash .......although i can't believe i just paid 200 bucks for this and now i'm gonna have someone tear it up

[slimthelineman]

yeah a little bummed myself but what can ya do? CC will work it out, now if i could just talk to someone there.....

[BrianG]

The only thing using an external BEC does is isolate any external loads. But no one knows exactly what is causing the BEC to fail. Is is overcurrent? Is it some voltage spike thing? Maybe just an IC reliability issue totally unrelated to current or voltage.

The mod is fairly easy to do, but there is room for problems. It can be done with an less-than-ideal iron, you just have to make sure you don't create any solder bridges or unsolder adjacent components with the heat.

The surface mount ICs have some sort of adhesive aside from the solder connections. So, breaking apart the ICs may be easier, but also increases the chance of wrecking a nearby trace if not careful.

In my case, I removed the components in the following order mostly due to ease:

1: Desolder the fan connector.

2: Cut the small leads connecting the coil itseld to the connections leading to the PCB. Then, remove the leftover leads.

3: Desolder the two FETs. If your iron is not small enough to do this reliably, you can break apart the two FETs, and then desolder the little leftover legs still attached to the PCB. Clean as much extra solder off as possible to avoid bridging to nearby traces.

4: Desolder the 8 pin IC (10 pin on the V2). Again, if your iron is not small enough to do this reliably, you can break apart the IC, and then desolder the little leftover legs still attached to the PCB. Clean as much extra solder off as possible to avoid bridging to nearby traces.

5: Desolder then external switch wires. The switch can't be used anymore, so it's not needed. Simply bridge the solder pads where it was connected. This will make it "on" all the time. This needs to be done, trust me.

6: While you have the MMM apart, make some foam padding to protect the rest of the ICs from the case. Cut a strip of 1/8" thick foam and place it over the 3 motor solder connections. Cut two squares of foam and place it over the 2 power solder connections.

7: Reassemble the case.

Below are some pics:

V1 MMM showing components to remove:



V1 MMM showing mods completed (switch bridge graphically altered because I didn't have an actual picture):



V2 MMM showing mods complete (courtesy of Joe Ling - slightly altered for size):



A little schematic showing how the external UBEC could be attached:

[GT35R]

The BEC issue isn't related to the meltdown though is it??

I am happy to remove the parts (thanks BrianG), and it seems this can be done before or after failure.
But having the whole MMM combust on a plastic model is no appealing thought.
I would have guessed that was a separate issue due to overloading/current spikes, but
the setups listed don't appear to be that extreme (only going by what others have said).

So it has to be asked of those who have had a meltdown (their MMM that is) was it, quote
"More Than You Can Handle?"

[BrianG]

GT35R: No, meltdowns are something (usually) totally different. That type of thing can happen to any ESC. The BEC issue is when it outputs 0v or close to 0v.

linc: Yeah, I suppose it did sound arrogant.

[ptt81]

Originally Posted by BrianG

GT35R: No, meltdowns are something (usually) totally different. That type of thing can happen to any ESC. The BEC issue is when it outputs 0v or close to 0v.

linc: Yeah, I suppose it did sound arrogant.

I was wondering what is the purpose of the bec mod above if it doesn't help with melt down problem? why is it not the same as using an external bec beside that it won't disable the internal bec

[BrianG]

The MMMs with melt down is far less common than the ones with BEC problems. Generally, the ones with BEC problems can be fixed with this mod.

Using an external BEC is all fine and good, but if the internal one goes south, the ESC is dead, even if the external BEC is still perfectly fine. Since we don't know exactly what causes the BEC issue, so using an external one (without disabling the internal one) may not help at all.

[ptt81]

Ok so to my understanding I can continue to use the external bec until the esc died without smoking, I can then do the bec mod and get it back to live? or is it too late by then?

[BrianG]

It should be able to be broght back to life then. However, if the mod doesn't help (or you accidentally messed up something doing the mod), your warranty is void.

[GT35R]

Bah, what good is the warranty when some of us have to pay international shipping and wait ages anyway. And just to have it replaced by another potentially faulty unit.
Heck, Traxxas replaced my VXL-3s for free incl postage after I had opened it and sawed the female bullets off among other things.

[BrianG]

OK, just wanted to reiterate the disclaimer. Don't need people saying "BrianG said this would work for sure and it doesn't, and now I can't even get it fixed under warranty."

[joeling]

Well, I went to the track to test V2 in X2 today. Inconclusive. The External BEC & mod bits definitely works. However, after a few laps round the track, the truggy stopped. When I went over to check, I noticed that the top cover of the esc had dislocated from the bottom cover. Also noticed that one of the 6.5mm connector on the battery side was very loose. So fixed everything & use some zip ties to tie down the esc. New problem, the truggy was cutting out under throttle like a typical lipo cutoff situation. I check with my multimeter but the battery was fine. I tested the truggy off the ground & it looked ok. I'm kind of puzzled.

Earlier, I had set the lipo cutoff to 15.5V for 5S. I checked just now & it's still there. I changed to auto. Hopefully I can test it again later tonight.

Regards,
Joe Ling

[joeling]

Ok, after some detective work, I am having fixed feelings. I think the esc is fine but the motor is stuffed. I cannot rotate the rotor my hand. This could mean that the magnet is shattered or something. 1515 2200KV Tekno rc Neu motor. First outing for it too. Guess I have to send something far away to USA afterall...

Regards,
Joe Ling

[Webwiesel]

Hi

My Monster died after 10 min with this BEC failure. Did someone tried to bring a Monster with BEC failure back to Life with this mod??

Because if i have to return it to Castle, shipping would be 1/4 of the ESC cost (overseas) + a lot of waiting time.

Greetz
Webwiesel