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Jittering Motor...

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by scalhoun, Sep 23, 2015.

  1. scalhoun

    scalhoun Active Member

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    Hey guys,

    jrks and worm gear motors. Rig has been running fine for last year. Tonight one of the jrk's lost connection in windows and had some random disconnects. When I kick the motor on it kinda does a spastic jittering thing and I have to shut it off quick.

    I seem to have fixed the usb disconnecting problem and I recalibrated the max and min values and applied the settings. Still got the spastic jitters.

    Any ideas on where to start? My first guess was feedback but it seems like it's reporting correctly when I move the motor lever around.
  2. Ads Master

    Ads Master

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  3. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    My guess would be a failing PSU or pot.

    It could be something simple like the pot connection being loose, as that would give jitters if it were trying to center itself but couldn't. Or the pot could be damaged.

    Lost connections and disconnects can be signs of a failing PSU, though could be triggered by wild spikes caused by something else.
    Last edited: Sep 23, 2015
  4. bsft

    bsft

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    Start with the pot. If its half buggered, it can cause the motor to twitch like a bastard and cause errors. Replace that first
  5. Nick Moxley

    Nick Moxley Well-Known Member

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    Or at least confirm its reporting properly in the JRK utility, Move it in SUPER small increments and watch the Trarget and Scaled feedback at the top of the screen, I would assume you could catch it jumping around if its buggered.
  6. scalhoun

    scalhoun Active Member

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    Thanks guys. I'm gonna order some spares and in the process I'm rewiring my rig, and the way the pots are mounted. It's been a long time coming just never go around to it. :)

    So quick question, right now I have my 3 power supplies plugged into a power strip:
    If I moved them into a case and cut the ends off the power cords and wired to one input like this:

    61n0Ewsv5vL._SL1100_.jpg

    amazon.com/URBEST%2525C2%2525AEInlet-Module-Switch-Socket-IEC320/dp/B00ME5YAPK

    Anyone see any issues with that or should I suck it up and run 3 input jacks for power on the case? :) I have the 575w power supplies so looks like my max load ever would be 15A total, but I don't think it ever gets that high. Now my problem is those sockets are only rated at 10A.

    Any suggestions?
  7. bsft

    bsft

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    What the power supplies draw and what they put out is irrelevant. Ive got a 10 way power board on my sim, plugged in is the PC with 1100 watt power supply (uses about 850 watts), 2 x 12 v 40 amp PSU, 40 "tv, speakers, wheel and pedals, not a problem, in fact, when I had my 2 hire sims, I could run them BOTH off another extension lead from the 10 way power board. So potentially 3 sims running flat out off one 10 amp 240v socket.
    Power supplies are designed to put out more power at lower voltages than what they draw. So you could have a 12v 100 amp PSU running off a 10 amp main plug. Its because of the components in the PSU that decreases voltage but significantly increases current. Thats mosfets for you, marvelous little buggers.
  8. Kirk

    Kirk Member

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    Looking at your locations, it's important to note that, in the USA, wall outlets are 120V and not 240V, so in the USA, you could NOT have a 12v 100A PSU running off a 10A mains plug.

    Running 3x 575W PSUs off a single 15A leg is possible as long as nothing else is on that circuit. Also, understand that when you first turn on the PSUs, the inrush of current as the capacitors charge might trip your breaker (some breakers are very picky, if it happens more than once, I'd replace it, the next one probably won't be as picky). I recommend not using that switch, but instead one that's rated for 15A. The problem with using underrated switches and wires is that, over time, they heat up, which increases the resistance, which causes them to produce even more heat (they are a higher fraction of the total load), and eventually results in failure and possibly a fire. The cost of a properly rated switch, compared to the deductible for your home owners policy, is tiny.
  9. Nick Moxley

    Nick Moxley Well-Known Member

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    I run 3 600pb's Plus My PC(850wpsu) and My Stereo 500w Pioneer, And my 47"TV+22"side monitor, And everything else, Shaker's(single gamer 2 90w a,p and 2 mini LFE's on a dayton 150w amp, LED's, Fans for cooling, Cable box ect ect ect, on a combination of 2 separate wall plug's, Both of which are on the same breaker which has never Once tripped.
  10. Kirk

    Kirk Member

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    I would be very very concerned. While the stereo and computer will both use far lower than their rated capacity, if your cable box is the DVR type, they can chew up a couple hundred watts all by themselves. A 120V 15A breaker is typical for north america (both USA and Canada), which equates to 1800W. This is for everything on that leg from the breaker box.

    Circuit breakers are an important safety feature, but they aren't perfect. Some trip faster than others, even from the same manufactured batch, and they can go bad. If they go bad by staying open, easy peasy. Pop in a new one, on come the lights. If they go bad by fusing closed, you might not know you have a problem until disaster strikes (a fused breaker is not in itself a fire hazard, but a overload that can't be interrupted most definitely is).

    About three years ago, I had a breaker get fused, it was a dedicated one for the fridge. I had no idea that it was fused shut until one night, the fridge door came open while we slept, the compressor overheated, and rather than the breaker tripping, we had a wall fire. No real damage, we caught it in time (smoke detectors), but that breaker was replaced and the others checked immediately after the fire. We also had to replace wiring in the all, not cheap.

    A working breaker is the difference between inconvenience and disaster.

    If you have access to a meter or a "Kill-A-Watt" device, please confirm that you aren't over 1800W and the breaker is not tripping.
    NOTE: Your power supplies consume more or less current depending on what the motor is doing. A rapid change of direction under load could come very close to the power supplies rated maximums. I *encourage* you to run a separate power cable, as 3x 600pb power supplies will consume most of the available current all by themselves when running at capacity.
    • Informative Informative x 1
  11. scalhoun

    scalhoun Active Member

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    Ok I think my pot setup may have worked the pots harder than normal and screwed them up a little bit. It will give me some clean values but then it some spots the numbers in jrk utility are twitching back and forth like crazy. for example 683 back and forth to 700.

    I'm gonna order some new pots while I have the rig tore down for a rebuild.

    Anyone think there are better pots to use verses these?
    http://www.alliedelec.com/bourns-6639s-1-103/70153381/
  12. Historiker

    Historiker Dramamine Adict Staff Member Moderator Gold Contributor

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    • Agree Agree x 1
  13. bsft

    bsft

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    I use pots like those, they work fine
  14. tombo

    tombo Active Member

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    Hello,
    I can't see pictures of your rig, but are you using flexible couplings? These will help the pots to last longer.
    • Agree Agree x 1
  15. scalhoun

    scalhoun Active Member

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    I've had them laying around, was using a rubber tube from original build :) I'm in the process of rebuilding now so I have those installed.
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  16. scalhoun

    scalhoun Active Member

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    So my jittering issues on the same motor/jrk reappeared. It may have been around longer than that and I just didn't notice as it got worse. We have gone from jittering to complete loss of feedback.

    I assumed it was still a bad pot so I threw a brand new one in place with the same results.

    I have also moved the jrk to another motor setup (pot/motor/wiring) with the same results so I'm down to the jrk /power supply being the issue.

    If I reboot the machine or sometimes unplug/plug the usb to jrk it will work with feedback for an unknown period of time. Then feedback completely drops and the motor goes into a full spin. At this point I have zero feedback until I reboot or unplug and my feedback will reappear.

    Has anyone ever seen a JRK do anything like this?

    I'm hoping to flash the firmware this week to see if that helps before completely replacing the jrk.
  17. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    Change the USB cable and if that does not work try changing the PSU as lost connections and disconnects can be signs of a failing PSU.