running dual steering servos off of MMM - RC-Monster Forums

cham · **running dual steering servos off of MMM -** 01.05.2011, 09:21 AM

I have tried everything guys. I am running a MMM v3 with spektrum sr3000 dx 3.0 I hooked the esc up to the 2nd channel of the rx, and the steering servos connected to rx "steering" port. But when I try to turn the wheel on the the tx the servos dance back and fourth and the mamba 1520 revs up and becomes unstable. I was wondering if I need to run a bec to run a dual steering servos? The steering servos are jr650's btw. Can anyone help me? I have the motor mounted, the lipos charged, and I am freaking itching to get this bad mofo out! Ive never seen a BL truck run before and its driving me nuts, but I guess all good things come to those that blah blah blah... ;)

bdebde · 01.05.2011, 09:37 AM

You may get it to work with just a capacitor on the receiver, but a bec would be the best bet.

DrKnow65 · 01.05.2011, 09:46 AM

Cham, I had to use an external BEC with my MMM and a single high speed servo, so you may very well have a low voltage issue. My system acted differently though, it would just shut down my receiver and the MMM would re-arm.

It sounds to me more likely that you have some radio frequency interference happening. Make sure that none of your servo wires or antenna are too close/parallel to the motor wires. Try unplugging the motor wires, does the problem go away? Are any of the servo wires pinched and making a circuit with the chassis? Does it run a single servo and the motor OK? Does it run just the MMM and motor OK? Any chance you can add a capacitor to smooth the voltage to the radio?

Also make sure that all the connectors are the right way in the receiver (I.e. The ground/black or brown wires of the servos are all twards the outside edge on the rx).

josh9mille · 01.05.2011, 10:37 AM

Seems like it should work fine, erevo's come stock with 2 steering servos and a MMM and there is no other special stuff.

cham · 01.05.2011, 04:13 PM

actually it does work just fine with one servo plugged into the rx! What does that mean? Is there not enough juice going to the two?

josh9mille · 01.05.2011, 04:25 PM

Quote:

Originally Posted by cham

actually it does work just fine with one servo plugged into the rx! What does that mean? Is there not enough juice going to the two?

did you try plugging in each servo seperately? or just one servo? Maybe one of your servos are bad.

DrKnow65 · 01.05.2011, 05:52 PM

Yup, could be a bad servo (try each one), or it could have been that one was plugged in backwards.

If they both work independently but not togeather I'd say it's a voltage issue.

P.s. I'm assuming the system is not working well enough to be steering full lock and binding up the servos. Maybe with one servo plugged in set the end points, then pull the arm off the second servo, plug it in letting it center, then reattach the arm. Could it be that the servos are fighting eachother to center??? I.e. The servos were "out of sync"?

cham · 01.06.2011, 08:38 AM

Thanks for the suggestions guys! Actually I made sure and took off the servo horns before I tried to mess with it, just in case! I am going to give it another shot today and try it again!