Problem C11T board - spindle 0-10v output wandering and causing inconsistent spindle speed

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Thread: C11T board - spindle 0-10v output wandering and causing inconsistent spindle speed

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    Default C11T board - spindle 0-10v output wandering and causing inconsistent spindle speed

    Howdy,

    I have Mach3 (on a dedicated non-internet computer) talking to a C11T via a USB SmoothStepper. Things were fine for a good while but I recently noticed that my spindle speed began to be inconsistent. I hadn't really made any changes that I can remember to possibly cause this. I now replaced the dedicated 12V power supply that is feeding the C11T's 0-10v spindle speed control with a better one because I was previously using a crappy 12v wall wart. But that wasn't the problem. If I start the spindle in Mach at 75% of max, I get the expected 7.5v out of the C11T but the voltage drops down by varying amounts (I guess about 1v on average?) and I hear the spindle speed wandering as a result. It'll go back up to 7.5v at some points but mostly it's wandering between 6v and 7.5v.

    Any advice on how to proceed? (I'll also post this question in the Mach forum in case it's Mach related.)

    Thanks in advance,
    Tom

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    Default Re: Spindle output voltage (0-10v for VFD) wandering - causing inconsistent spindle s

    Probably the CT11 component going bad. It takes the PWM from SSand converts it to analog voltage

    Russ



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    Default Re: C11T board - spindle 0-10v output wandering and causing inconsistent spindle spee

    Tom,

    Use a shielded cable to take the analog output from the C11T to the VFD. Make sure to tie the shield to the ground of the VFD, not the C11T.

    Arturo Duncan
    Welcome to CNC4PC



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    Default Re: C11T board - spindle 0-10v output wandering and causing inconsistent spindle spee

    Thanks for the speedy reply, Arturo. I was grounded on the wrong end but I just switched it around and the problem persists. I guess I shouldn't be surprised as I think it was running OK for a while as it was. But I'm glad it's now wired the correct way around. Do you have any other suggestions?

    As a backup plan: I think I can control my Hitachi VFD with a pulse train up to 32khz and I was reading up to see if I can do that straight from pin 14 and avoid the 0-10v stuff altogether. I need to read through some more docs to get familiar with how I'd go about configuring that in Mach3. I think I already understand what to do on the VFD side.



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    Default Re: C11T board - spindle 0-10v output wandering and causing inconsistent spindle spee

    Tom,

    Yes, it is possible to wire it to work with the frequency instead of the analog signals. It will be more accurate.

    Going back to the analog signals problem:

    - It would be interesting to connect a multimeter to the analog output and see if the analog output is indeed varying on the C11T.
    - I would also test with a fresh profile to rule out XML profile issues.
    - Do you see any particular pattern on the speed varies? any particular motion? There could be problems with damaged chips on the board, and when certain pins are activated, a short could be induced on the board that drains power from other circuits.

    Arturo Duncan
    Welcome to CNC4PC



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    Default Re: C11T board - spindle 0-10v output wandering and causing inconsistent spindle spee

    Arturo,

    Checking the voltage output from the C11T 0-10v was where I initially found the varying voltage problem while also listening to the spindle to make sure the voltage dip correlated to the spindle rpm dip. But I took it a little farther just now during my break and disconnected the wires going to the VFD which are coming out of the 0-10v. I wanted to eliminate the possibility that it was VFD noise. And what I found is that I still see the fluctuating voltage. More interestingly, if I gently flex the C11T board in the area of the 0-10v out, I can reliably cause the voltage to dip or come back up to normal. So I must have a cracked trace or cracked solder joint or something like that. I think at this point I want to switch it over to using the digital pulse train and abandon the analog altogether. I suppose there could still be a problem depending on where the problem is on the board, but I'll cross that bridge if I come to it.

    Thanks as always for your help, Arturo.
    Tom



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    Default Re: C11T board - spindle 0-10v output wandering and causing inconsistent spindle spee

    Tom,

    Yes, that explains it. Yes, do the pulse train.

    Arturo Duncan
    Welcome to CNC4PC



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C11T board - spindle 0-10v output wandering and causing inconsistent spindle speed
C11T board - spindle 0-10v output wandering and causing inconsistent spindle speed