Er9x bug or hardware issue?

[Mehari]

I have two transmitters; a Turnigy 9X and a Turnigy 9Xr, both exhibiting the same symptoms when trimming.

On both transmitters the Model Setup/Trim Switch is set to TRN to enable trims to be reset, i.e. window trims to be transferred to the subtrims and cleared.

Recently I noticed that subtrims were getting quite out of whack after using the TRN switch a few times.

On further investigation I find that if the sticks are centred perfectly (both cursors are zeroed in the EXPO/Dr menu) then when there are no trims present in the display window, hitting the TRN switch does not change the subtrims. If I then move the sticks around until they are not centred in the EXPO/Dr menu (i.e. not showing zero on both axes) and hit the TRN switch a few times the subtrim changes quite a bit. I checked with a couple of other 9X transmitters running Er9x and they show the same symptoms.

Presumably this is a stick centring issue which is mechanical and cannot be overcome. If so it is a shame as the trim reset feature is a great tool.

Am I right or is there a software workaround?

[Daedalus66]

You are misunderstanding how this feature works. It is not about merely transferring and zeroing the trims. It is primarily intended to transfer stick settings. So of course if the sticks are centered nothing should happen when you hit the switch, but if they are not centered subtrim should change.

"InstaTrim" is intended to allow you hold whatever stick displacements are necessary for straight and level flight and to transfer them (along with any trims that happen to be in effect) to subtrim. It is used by flying the model, holding the sticks as required, hitting the switch and immediately releasing the sticks.

Here is the explanation from the manual for the Turnigy 9XR Pro:

Trim Switch (“InstaTrim”)
When this switch is activated, the current position of the sticks is copied to the subtrim settings (Limits page). Choose a switch that is easily reached but unlikely to be flipped accidentally (e.g., RUD). The function is triggered by moving the switch from its default position. To trigger it again, the switch must first be moved back to its default position.
This function is very useful for first flights, as it avoids the need to take your hands off the stick to press the trim buttons. Simply hold the plane level with the sticks and flick the selected Trim Switch. Immediately centre the sticks and the plane is trimmed. Fine trimming can still be done with the trim buttons.
NOTE: It is advisable to disable this function once initial trimming is completed as it can have seriously negative results if triggered accidentally!

[Mehari]

Thanks for the response.

I take your point however the Er9x manual that I work off (a fairly old one) also adds that after copying the stick positions this function zeroes the button trims, that is, it copies the stick positions AND adds the button trims. If the sticks are centred it merely transfers the button trims. I have used it many times in the past after a flight to transfer and zero button trims. The sticks of the particular transmitter I had used previously always centred properly so there was never any problem. It wasn't until I used this function on a transmitter with a poorly centreing rudder pot that I discovered that it was causing my rudder subtrim to get further out of whack each time I hit reset, that is, the subtrim was changeing even though the button trim was zero.

Clearly this function is not designed to deal with a non-centreing pot (although I suspect that the program could be modified to compensate for this) and in future I will only use it for initial setup.

Thanks again.

[jhsa]

That's how it should be used.. the initial setup.. I wouldn't expect a model to be 100% trimmed by using this feature. This is intended to take you out of the s**t quickly when you maiden a plane that has serious problems

João

[Daedalus66]

Thanks for the response.

I take your point however the Er9x manual that I work off (a fairly old one) also adds that after copying the stick positions this function zeroes the button trims, that is, it copies the stick positions AND adds the button trims. If the sticks are centred it merely transfers the button trims. I have used it many times in the past after a flight to transfer and zero button trims.

A better way to think of it is to say that it transfers to Subtrim the values of the inputs (I.e. sticks and trims) that are currently being used to hold the model in straight and level flight. It zeros the trims and you must release the sticks. It's strictly for use during flight.

The trim zero function alone (for use after flight) is at the bottom of the Limits page.

[Mehari]

The trim zero function alone (for use after flight) is at the bottom of the Limits page.

[/quote]

Aha! That had escaped me. Thanks a million. You just put me on the right track.