24V PSU (two 12V PSUs) interference [Solved]

Hi all, after one week I determined the source of an interference coming from the 24V PSUs to the load cell of my pedals. This behavior is relatively new to me, but I was running simultaneously into two issues, first the load cell was showing some issues and the second issue is now the interference.

If I power on the 24 PSUs braking is no longer possible, the signal coming from the cell is very jerky and jumps from 0 to 100 and back, so say there are massive dropouts still on the pedals after replacing the load cell (got one from a local dealer).

What can I do to suppress the interference of the PSUs? Should I use ferrit cores? If so, on the 220V line or on the 24V line? Or only on the USB?

@Alexey @RacingMat @pipis2015 @OZHEAT @BlazinH @SeatTime @speedy

Thank you guys ...

I had the same issue with stock pedals.
Tbh never thought to put ferrite cores.
My exact problem was that after massive demand from the psus (fast continuous abrupt small rig movements/vibrations eg F1 hitting the rev limiter) the brake pedal registered less than half the bar on asset to corsa ingame pedal graph.
Problem was solved only by restarting the wheel.
So.
I powered the wheel from a different socket (wall outlet) and my braking problem was solved.
Weird to see that you have problems on the brake pedal too.
Maybe a flaw on the t500rs design?

Starting the problem braking output is jerky but it ends up with less than half of the usable travel/force ..and sometimes no braking at all until wheel reset.

@pipis2015 I am using the DSD pedals and the brake uses a load cell. The DSD pedals uses a separate 12bit controller. No T500RS so far

EDIT - not solved :-/

Do you have a wiring diagram for your load cell setup? You may want to put a capacitor on the input power rails to the load cell amplifier.
If the load cell amp already has this it may be signs of a failing power supply. DC should not have any noise whatsoever.

Pit, are the pedals plugged directly into the PC USB port or through a powered hub? I have no idea why but I had the same issue with my Fanatec pedals with my motion PSUs turned on. Plugging them into the PC USB port solved it (this was true for both the pedals and the CSW base as well).

Very weird: when I disconnect the PUs from the 24V wire (the PSUs are close to the rig) and if I power on the PSUs only, the signal of the cell is jerking. If I power off the PSUs, the signal fails down until zero for one second then comes back to standard. If you want I make a video for better understanding.

The controller:

The wiring of the load cell:

The load cell:
http://www.phidgets.com/products.php?category=34&product_id=3135_0

@Historiker thank you for the hint, but it is directly plugged in to the PC USB port - but probably the USB is too long...(2.5m)

Thank you for this input. If I would use the capacitor where should I put it?

Looks like the controller already has the required capacitors. So the 24v supply is in no way connected to the pedals? Is the controller powered by the USB? You could try a ferrite core on both ends of the USB cable but without knowing the frequency of the noise they may do nothing at all. Could possibly be voltage dropout across the USB cable. Problem sounds really weird. Either way there should be a path for the noise to couple with the pedal. is any part of the 24v system near the pedals?

These kinds of problems really suck because it could be something really simple or really hard to find.

Also, if you have the USB plugged into the front panel try using the USB directly on the motherboard.

Brain is dying... Must go to sleep now. Good luck!

@Alexey as a result of your thoughts and inputs I tried out an other PSU for testing purposes but 12V. NO issue any more.

@Pit
Good to see you resolved your brake problem.

With your 24v PS, I'm guessing it is a switch mode PS.
I would say that the smoothing capacitors are shot which would account for the high frequency DC ripple.
SMPS do not like power being backed fed and with motor reversals or braking it will result in much higher than 24v across the 24v output terminals.
The smoothing capacitor is there to average out the pulses from the PWM, the cap is probably rated around 25v - 50v and has been overloaded damaging it. You could pretty easily find and replace the caps but be aware there are some other caps of high voltage which if not discharged can kill you.
Your leads to your load cell is probably running parallel or looped with the 24v power lead somewhere. I would recommend shielded cable to reduce RFI.
The 24v ripple was strong enough to disturb the signal from the load cell and because the load cell is connected to an op-amp it got amplified.

Sorry if this is too much info especially as you have fixed your problem but I like to analyze problems before repairing.
Cheers Andy

@OZHEAT would that be a Y Capacitor?

@Historiker,
What is a "Y capacitor"?
The faulty cap will be an electrolytic polarized capacitor.
Cheers Andy