Jitter on all axes on FFB Pro, but only with FFB active - perhaps EU 60hz power?

[KTeichel]

Hi,

I'm one of those using the adapter for an old Sidewinder Force Feedback Pro, and (like other users) I get visible jitter on all of the axes unless they are fully deflected.

I wanted to share my observations about this, so that hopefully it can help find a fix eventually.
I noticed that the jitter only happens with the power supply plugged in.
Being located in Germany, I thought that it might have something to do with the power line frequency being different in US (60hz) vs mostly the rest of the world (50hz); I haven't looked at a 60 vs 50 hz oscillation in comparison though.
On closer inspection, it is not simply the PSU being plugged in, it seems to be rather the question of whether or not Force Feedback is actually active: if I toggle everything (including spring center) off in a utility software, the jitter goes away.
The only effect where the jitter isn't always visible (not visible when I don't touch the stick, that is) is "friction" - I don't know how motor activation works for different effects, but maybe that tells us something?

Anyway, best regards and I hope this can be of any help.

[NolanNicholson]

This issue is seemingly common to all Force Feedback Pro joysticks. I live in the US, and my stick behaves the same way. Others have even tested the joystick on a native Gameport card and found the same exact behavior - axis values jitter whenever the FFB motors are on.

It's unclear whether this is the result of aging (in which case it has occurred surprisingly consistently with basically all of these joysticks), or whether this jitter was always present and nobody originally noticed it. In any case, the USB adapter is highly unlikely to be at fault.