On initial contact with Mtroniks they told me the problem was down to me. First saying that my Tx setup was wrong, and after that telling me I needed to reverse the throttle. Today, however, they've changed tune and more-or-less admitted they know about the issue. Why the $%£& didn't they say so straight away?
The reason for the issue you are seeing is that the speed controller looks
for a 'window' of throttle travel when going through set up. If the 'window'
of throttle it sees is larger than the speed controller thinks is
acceptable it will use the extreme of throttle that it sees and is happy
with as its full throttle position. If when you apply throttle you go past
this point the speed controller will, in effect, drop of the end of the
scale and therefore default to neutral.
This issue is a new one that has cropped up recently due to transmitter
manufacturers changing the way they design the throttle range.
This issue is solved, from our point of view, with the new Mtroniks tio
Marine controllers but can be an issue on some Viper controllers, and this
is down to tolerances as it doesn't happen with 99% of the Viper controllers
that are in the market.
The way to solve it when using a viper is to simply move your throttle trim
back a few notches, then go through set up again. What this does is move the
throttle window of the transmitter down a bit and back into the area that
the Viper speed controllers are happy with.
It seems somewhat complacent to say that the "issue is solved" because Mtroniks have another model of controller which doesn't suffer the same defect. If only 1% of Vipers suffer the problem then an immediate offer to exchange the units would seem to be the best policy to preserve Mtroniks reputation. But instead they gave me a bit of a run-around and then finally came clean and told me I'd have to live with it. So - call me cynical - could it be that rather less than "99% of Viper controllers that are in the market" really work OK?
Maybe I'm in a minority when I expect stuff from a 'reputable' brand to work as advertised. But my Vipers are in the post for refund. Not buying that model again.