Ofna Micro Fail-safe install

Nothing is going to happen if you turn the receiver off, that's why you have a throttle return spring.

It should work if you turn the transmitter off, fail safes work when you loose/interrupt TX signal or when battery
voltage drops below a certain point it moves the throttle servo to a preset point.

The fail safe will do nothing if the RX looses power or you switch the RX off, that's why you need the
TRS to pull the throttle back to idle.

That's my mistake. I meant to say that if I turn the transmitter off, nothing happens.

Nitro4910 said:

Nothing is going to happen if you turn the receiver off, that's why you have a throttle return spring.

It should work if you turn the transmitter off, fail safes work when you loose/interrupt TX signal or when battery
voltage drops below a certain point it moves the throttle servo to a preset point.

The fail safe will do nothing if the RX looses power or you switch the RX off, that's why you need the
TRS to pull the throttle back to idle.

Click to expand...

What radio system are you using?

If it's working & set up right then it should work when you switch off the TX.

For testing try bypassing the optidrive and plug the failsafe directly into the RX then into the throttle servo & try it that way.

Nitro4910 said:

What radio system are you using?

If it's working & set up right then it should work when you switch off the TX.

For testing try bypassing the optidrive and plug the failsafe directly into the RX then into the throttle servo & try it that way.

Click to expand...

Didnt work. I have to be doing something wrong.
I have the stock radio.

Is there anyone who has the Ofna Failsafe on there Revo 3.3 stock with Optidrive? Can you please post a pic of exactly where its suppose to be plugged into?

Strange thing is that If I turn the cars RX on first, the FS engages, but once I turn the radio on then back off, its as if the FS is not installed.

I'd like to add my findings after installing a failsafe to my TMaxx with 2.4Ghz radio.

I wanted to add a failsafe as the built in one as far as I am aware doesn't allow for the batteries going dead or being disconnected (not sure if being disconnected works on any though?)

Mine seems to work like your describing. I had to apply brakes, then press set. When I switch RX on first before TX mine also applies brakes as if failsafe is working.

The only thing it (sometimes does) is if I apply full throttle then switch off the RX, the throttle return spring pulls the throttle back. Before the failsafe, it just seemed to keep the throttle held open. Don't know if this is how it should be. Wouldn't of thought so. Also sometimes it still does this with the failsafe connected.

Hope this makes sense. It is very early.

I'm not sure if it's the two failsafes that are counter acting one another. I just hope that if the worst happens, one of my failsafes will work.

---------- Post added at 6:04 AM ---------- Previous post was at 5:58 AM ----------

Also, since fitting the failsafe my throttle servo when at WOT can be a little bit twitchy?

Anyone know why that could be?

nautcasprt6 said:

Didnt work. I have to be doing something wrong.
I have the stock radio.

Is there anyone who has the Ofna Failsafe on there Revo 3.3 stock with Optidrive? Can you please post a pic of exactly where its suppose to be plugged into?

Strange thing is that If I turn the cars RX on first, the FS engages, but once I turn the radio on then back off, its as if the FS is not installed.

Click to expand...

Sounds like it is not recognizing the lost TX signal.

Reread the setup instructions and leave it plugged into only the RX throttle channel & throttle servo and try it again.
If it's setup properly and still doesn't work it might toast.
http://www.ofna.com/failsafe-micro.html

nautcasprt6 said:

Didnt work. I have to be doing something wrong.
I have the stock radio.

Click to expand...

Stock as in AM stock or 2.4ghz stock?

2.4ghz stock.

I ran through the instructions again yesterday and no luck.
I wish there was another truck I could test it on. I would buy a new one and see if that makes a difference but I dont want to buy it and then the same thing happens.
What FS is everyone using on there trucks?

Nitro4910 said:

Stock as in AM stock or 2.4ghz stock?

Click to expand...

nautcasprt6 said:

2.4ghz stock.

What FS is everyone using on there trucks?

Click to expand...

The 2.4ghz stock radio has a built in fail safe.

From Traxxas: Failsafe circuitry is built into the radio system. Should there be any interference or loss of signal, the receiver will automatically return the throttle to neutral and hold the last steering command. The failsafe system is built-in and does not need to be adjusted or activated.


Trying to install a 2nd FS always creates a compatibility issue.

Snook Man said:

The 2.4ghz stock radio has a built in fail safe.

From Traxxas: Failsafe circuitry is built into the radio system. Should there be any interference or loss of signal, the receiver will automatically return the throttle to neutral and hold the last steering command. The failsafe system is built-in and does not need to be adjusted or activated.


Trying to install a 2nd FS always creates a compatibility issue.

Click to expand...

So if I have a Traxxas 2.4Ghz radio system with their built in failsafe, then I don't need any other form of failsafe? I have a 4907 TMaxx

Yes, the 2.4ghz TRX radio doesn’t need a 2nd fail safe. Almost always when someone tries to install a 2nd fail safe there are compatibility issues and then neither failsafe (the built in, and the add-on) work correctly. It’s not just the Traxxas 2.4ghz system, but almost all radios with a built in fail safe are not compatible with an add-on unless the built in fail safe can be disabled.
The only real draw back with the Traxxas fail safe is it only returns the throttle to neutral instead of applying the brake, which is really no big deal since it will still prevent a runaway.

To test it, turn the RX (receiver) & TX (transmitter) on, apply and hold WOT and turn off the TX. The throttle should then return to neutral.

And as always, make sure the throttle return spring (TRS) is adjusted correctly to return the throttle to neutral in case of a power loss to the receiver.
With the RX and TX on, hold WOT then turn off the RX. The spring should be adjusted to return the throttle to neutral.

CupraR said:

So if I have a Traxxas 2.4Ghz radio system with their built in failsafe, then I don't need any other form of failsafe? I have a 4907 TMaxx

Click to expand...

Well if thats the casse, I bought this for no reason?
Anyone want to buy my FS, LOLOL.

Thanks Snook Man.

Very straight forward information.

I have fitted a secondary FS as I say just really for when/if my batteries fail.

Yesterday I was trying to run in an engine and was in close proximity to it when my battery pack ran out. The secondary FS did as it should though and applied my brakes as I had set it to do. Also as I've mentioned though, I now sometimes have a twitchy (only throttle doesn't do it when brakes are applied) servo.

Hmm, decisions. Should I leave it fitted or remove it!!!!!

The std Traxxas FS, if/when the batteries fail/die would apply a neutral throttle servo?

Low battery voltage will engage the fail safe and return the throttle to neutral.

In the event of battery failure, or if the battery would become disconnected from the receiver (say in a crash) NO fail safe can then return the throttle to neutral or apply brakes. There would not be any power to the receiver to power the servo and both the throttle/brake and steering servo would hold the last position it was in before the power disconnection.
A TRS is your only alternative in the event of total loss of power to the receiver.

Snook Man said:

Low battery voltage will engage the fail safe and return the throttle to neutral.

In the event of battery failure, or if the battery would become disconnected from the receiver (say in a crash) NO fail safe can then return the throttle to neutral or apply brakes. There would not be any power to the receiver to power the servo and both the throttle/brake and steering servo would hold the last position it was in before the power disconnection.
A TRS is your only alternative in the event of total loss of power to the receiver.

Click to expand...

Ah, I see. Thanks for clearing that up.