Logitech g940 Center Issues

[VirusAM]

Good morning,

I managed to buy an old g940 and I would like to mod it.

But when arrived, applied the fred41 firmware and then I tested it.

I saw that it has a sloppy feeling in the center, only for the Y axis, and the spring forces are never able to completely center the Y axis.

If I pull the stick back and then release it, it centers at -2% (logitech control panel), if I push it forward and then release, it centers at +6/7% (always logitech control panel readings). But when used in game with non FBW aircraft this is not really an issue since the trim force (for heli, or F14/A10C etc) is able to keep it where i trim it, but if I use the F16 or the Hornet with it, it don't center correctly (with similar behaviour as seen in the control panel).

So I would like to know if this behavior is normal, or I have some issues (for example a tooth of the gimbal cog is ruined). The sensors seems to be perfectly ok.

If needed I can upload pictures of the control panel showing this behavior.

Thanks everyone for taking the time to read this.

 

[edmuss]

No experience of the 940 but if there is any backlash in the gear drives then that could affect the centre point.  I would take it apart, inspect each gear and spindle in turn and reapply grease to any that might be dry.

Do you know if the sensors are potentiometers on the gimbal axes or encoders on a gear?  It could be if it uses optical encoders (as logitech do with their mousewheels) then one of the encoder trigger holes may be blocked.

The above is purely speculation from an engineers perspective and might be completely wrong

edit: just looked it up and it says it's contactless so I would guess either a single hall sensor like the warthog or X&Y optical encoders somewhere in the geartrain.

Edited March 31, 2022 by edmuss

[VirusAM]

49 minutes ago, edmuss said:

No experience of the 940 but if there is any backlash in the gear drives then that could affect the centre point.  I would take it apart, inspect each gear and spindle in turn and reapply grease to any that might be dry.

Do you know if the sensors are potentiometers on the gimbal axes or encoders on a gear?  It could be if it uses optical encoders (as logitech do with their mousewheels) then one of the encoder trigger holes may be blocked.

The above is purely speculation from an engineers perspective and might be completely wrong

edit: just looked it up and it says it's contactless so I would guess either a single hall sensor like the warthog or X&Y optical encoders somewhere in the geartrain.

 

Thanks for your reply,

Anyway using simffb and trying the progressive trim option, i see that this way the stick is able to stay precise in 50%, so it seems it could also be a calibration option. But the software offer no option for calibration. Is there some alternative software which can be used for calibrating the axis?or that can keep the stick axis "trimmed" forever?

About the sensors, they should be contacless sensors (hall?) similar to the ones in the Warthog. No pots for sure.

[edmuss]

2 minutes ago, VirusAM said:

Thanks for your reply,

Anyway using simffb and trying the progressive trim option, i see that this way the stick is able to stay precise in 50%, so it seems it could also be a calibration option. But the software offer no option for calibration. Is there some alternative software which can be used for calibrating the axis?or that can keep the stick axis "trimmed" forever?

About the sensors, they should be contacless sensors (hall?) similar to the ones in the Warthog. No pots for sure.

Can't help on the calibration front I'm afraid, not had a FFB stick since the mk1 M$ sidewinder FFB!

My thoughts with the optical encoders, if a blob of grease has fallen and blocked one of the timing ports it would give an imprecise count and could throw out the sensor in that axis only.

It's the sort of thing that I like to take apart to find out how it works

[VirusAM]

Those does not seem to be optical encoders. I dismounted it, and everything seems fine (the cogs are ok)
Maybe it is the motor that has a little bit of play

[edmuss]

Is there any backlash in the gimbal/gear train?
Whilst it's apart when you move the stick does it start moving all of the gears straight away?

[VirusAM]

Any little and minimal movement in the stick rod, corresponds to a similar movement in the motor cog. So yes, it moves the gear right away.
Anyway I will try to apply some grease. 
About the backlash with power off there is not backlash...with the power on and the spring effects activated there is some play around the center, and as written in the first post of this thread, if I leave the stick in does not center correctly in the Y axis