MambaMax ESC quirk - Page 4 - RC-Monster Forums

crazyjr · 11.17.2006, 04:09 AM

My glitch with the 5700 mamba was like 1 and 3, never had 2 happen, but always wondered if it was possible

Finnster · 11.17.2006, 11:09 PM

I've had that occational glitch, like a momentary brake stab. Init thought it was a Rx problem, and started moving things around. Went away a bit w/ an FM and Rx pack, but it happens every now and then (unfortuantely after I nail the throotle and get going then, whack, then back to accel.

:032:

BrianG · 11.18.2006, 01:22 AM

I was reading back through this thread and just thought of something that may help. This quote from GD got me thinking:

Quote:

Originally Posted by glassdoctor

Castle's response so far is that they are blaming the connectors... they said that one guy reported a similar issue and that the problem went away when he direct soldered the motor. They think possibly the very small low voltage pulses that the MM uses to get info from the motor may not "like" the connectors. I tried putting a little solder "jumper" on my connectors to see if that would help and my buddy replaced his connectors with Corally style gold plugs that are similar to the 4mm stock ones but are a different (we think superior) design and quality. But we still see the issue.

What if there is too much noise on the motor/ESC wires under high current during startup so the ESC has a hard time correctly reading the feedback pulses? Or maybe there is some cross-induction of this feedback confusing the controller?

What I am going to try tomorrow is somehow shielding each motor wire from each other and then trying to duplicate the issue I'm having. However, my symptoms are not very consistent so it might be tough.

It's a shot in the dark, but worth a try. I'll report back tomorrow...

crazyjr · 11.18.2006, 02:58 AM

I have my wires braides on my 5700 and not on the mamba/9XL, I mean its possible but don't think it will matter. Good luck in tring to make it happen

glassdoctor · 11.18.2006, 12:49 PM

I haved wondered if braiding would make a differnence...

The thing about the glitch we have is that it's typically not under heavy load, like when you are just starting to accelreate hard out of a corner (from close to a standstill) but more when you gently get on the gas.... or are already at partial speed and then pull throttle.

Finnster · 11.18.2006, 05:59 PM

I have my wires braided, but my glitch is when its going a bit (not form a stop) and accelerating.

crazyjr · 11.18.2006, 09:20 PM

Quote:

Originally Posted by glassdoctor

I haved wondered if braiding would make a differnence...

The thing about the glitch we have is that it's typically not under heavy load, like when you are just starting to accelreate hard out of a corner (from close to a standstill) but more when you gently get on the gas.... or are already at partial speed and then pull throttle.

Glassdoctor, What do you have the timing set at? It may be possible that its trying to out-accelerate the motor, I run my timing at the lowest point and have no problems.When i get a front arm for my T4 i will try higher timing and see if i can get mine to do it.

BrianG · 11.18.2006, 10:16 PM

I have my timing set to low and I still get the cogging when doing the reverse-brake-forward thing.

crazyjr · 11.19.2006, 01:58 AM

you mean the foreward cogg while still going backward? I get that, but thought it was because the esc was confused and needed to stop before going foreward.

glassdoctor · 11.19.2006, 09:33 AM

I have tried all the timing setttings... in my buggy/4600 setup I start at normal and go up/down a notch if I want more/less power.

At the race the other night I ran both normal and high timing.

crazyjr · 11.19.2006, 03:46 PM

Ok, I was thinking that at a higher setting the esc might be trying to anticipate the acceleration, Just a thought

glassdoctor · 11.19.2006, 07:16 PM

You may have a point crazyjr... I'm not sure. I might try going to both extremes on the timing and just see what happens in the future.

crazyjr · 11.19.2006, 08:54 PM

I have mine set to the lowest right now because everytime i run it i break something, but no trouble

crazyjr · 12.02.2006, 04:56 PM

I had another thought on this subject (uh oh, lol), If the shrinkwrap on a couple of the plugs weren't completely covering the plug, would it be possible for them to touch of the feedback signal to jump the small gap between the plugs? My 5700 has one that is not perfect and thought if two or more were not right, there could be a problem

BrianG · 12.02.2006, 06:32 PM

That is possible, but it takes fairly high voltage to arc across even a small air gap. The electrodes would have to be VERY close together. But, if they were touching, that would short the motor wires and cause substantial ESC heat, if not immediate shutdown.

According to Wikipedia, it takes about 30,000v/cm to arc across air. I don't know if the induced feedback signals can spike high enough to get to that point.

Interesting though.