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Jul 15, 2019, 06:41 AM
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corsairman2's Avatar
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Radio problem or speed control problems


I have a Futaba T9CHP transmitter on 75Mhz and I am using a Futaba R149DP receiver with a Mtroniks Viper Sub 15 speed control. My problem is that the motors go into reverse when the stick is in the neutral position. The only way to stop it is to move the stick to reverse the forward then neutral. It happens over and over again. I have shut off items in my shop that might cause a problem, but it still happens. I have other subs with the same receiver and the same speed control and no problem. Futaba has told me that it is a speed control problem. Do I need to have the transmitter checked with the receiver to see if they are on the proper channel.

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Jul 15, 2019, 07:56 AM
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1. Let try connect the speed controller to another channel, program it, test it. if it is the same thing . (Or use a servo tester)
Bad speed controller.

2. Get a Y servo cable connect the speed controller and a servo to it, see if the servo jumping all over.
Servo work fine then is the speed controller
Servo not working, change to another receiver.

3. assume that you use the same transmitter on other boat, so not the transmitter.

4. May be power cutting off, BEC to the receiver (back to speed controller, test it by remove the red wire[+] to the receiver, add power back to the receiver to test it again) , on off switch, connector.

Something like that.
Jul 15, 2019, 11:47 AM
Registered User
Have you followed the initial steps for setting up the Viper ESC centering and throttle forward and reverse? The new ones might assume the first stick movement is forward. Might try reversing the channel on the futaba transmitter.
Jul 15, 2019, 10:38 PM
AKA Mr Pita
Have you tried it in a different channel? the trim and or subtrim may be out of adjustment on the throttle
Jul 18, 2019, 05:24 PM
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tchalfant's Avatar
I would second running through the setup of the Viper ESC. Changing TX, RX, or channel, I find running setup will remove a ton of issues.
Once we hear back from you, there are other things to check, but one step at a time.
Last edited by tchalfant; Jul 23, 2019 at 08:05 AM.
Jul 22, 2019, 06:00 PM
Registered User

RX and ESC Problem

I had the same problem with the Nautilus Drydocks Type VII electronics package. The procedure was pretty exact. Turn on TX and make sure throttle is in center position if using forward/reverse and trim in the center. Turn on the electronics package power and press the setup button on the Viper within the first few seconds. The Viper will learn the center position of the throttle as zero and the RX will be synced properly. What Sub and WTC are you running.

Hope this helps a bit.
Jul 24, 2019, 08:38 PM
Latitudes vs Attitudes
Bob Gaito's Avatar


If you follow a wide range of the RCG forum spectrum you will notice quite a large amount of posts about Mtroniks Viper complaints and questions about problems with operation...Most of the time it seems to be operational error..but to me looking at the posts from the outside, it also seems that the units are not user friendly-at all!..they will not tolerate any deviation from the instruction specs. Do not go over supply voltage-At All!.(12 volts means 12 volts , not 12.8 volts after a full charge) Pay strict attention to initial startup instructions-these are not plug and play devices. DO NOT have both BEC red wires connected in twin engine situations (most other ESCs now will tolerate this condition.) Some operators have even installed optical isolators to rectify problems with feedback in twin engine installations or RF chokes to quell an undefined Interference problem . A few have just returned the ESCs in question as defective for exchange (were they damaged by improper usage or genuinely defective?) I rarely see problems with the other(Name brand) ESCs in the posts...A quick search of the forums will produce many posts of problems with these units (not just the submarine units but also the boat versions..People Why Bother??
Last edited by Bob Gaito; Jul 24, 2019 at 08:46 PM.
Jul 25, 2019, 09:29 PM
Registered User
I had the same issue with mine, also the arkmodel type 7 kit from Bob Martin. I went theough the set up twice before getting it correct. Turn your transmitter on zero out any throttle settings you may have on the tx. Set the throttle throw to between 90 and 100%. Press the setting bottom on the speed controller until the lights begin to flash rapidly. The viper speed controller will be done finding the throttle neutral when the lights stop flashing rapidly.

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