Esc problems

[nicebutdim]

Hi all, a plea of help to the more elecrtonically gifted here I converted my Schoema to rc a little while ago and up until yesterday everything was going fine. Basically when travelling forwards the power is smooth and good, but in reverse it seems to 'surge', kind of slowing down then surging back up to speed then slowing again, repeating this about every 1-2 seconds. Very frustrating when shunting as it tends to ram stock just as it is about to couple up. I'm running 12 1.2v rechargeable aa's, code 'core' 2 channel 2.4ghz radio and the Mtroniks Viper 10 loco esc. The esc is the one that I don't see being listed very often, apparently able to cope with 16v and 10 amps, instead of the current loco 10 that can only deal with 12v. I've switched over to track power (which disconnects all the rc gear and reverts the loco back to original power) and it runs fine in both directions, so I'm guessing it can only be the speed controller. Current consumption seems to fine too, well within limits.
Any help would be gratefully received.
Many thanks,
Tim

 

[Moonraker]

This is a "feature" of Mtronics controllers which we, at MyLocoSound, have had to spend a lot of time on. When going forwards the Viper outputs a clean waveform. However, their way of going in reverse is different to any other ESC I know of and produces an erratic waveform. We had to specially modify our soundcards to work adequately in reverse with the Viper. Mtronics ESCs were originally designed for racing cars and therefore reverse motion was not important and was added later as an afterthought.

Regards
Peter

 

[MRail]

Perhaps the best "fix" would be to fit a DPDT switch in the motor wiring.
Add a servo and use the RC to select forward/reverse.
Depends on space of course.
Many of us use this method on non-reversing esc's.

 

[nicebutdim]

Thanks guys. At least I know it's not anything I've done, Peter has put my mind at rest there. I have a G Scale Graphics rc trigger board laying around somewhere, I'll connect that to a dpdt relay on latching mode and re-calibrate the esc so it uses the whole of the throttle sticks travel.
Thanks again,
Tim