Need Help with Advanced Motor Controls 25A20 drives


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    Default Need Help with Advanced Motor Controls 25A20 drives

    I have acquired 3 25A20 brushed servo drives for a LinuxCNC conversion, but I am not having any luck getting them to work. They appear to be very simple to connect; HV power in, power out to the motor, 2 tachometer wires. At that point I would think it should try to lock the shaft when powered on without any other inputs connected. Instead I get a red light indicating a fault.

    I have the dip switches all off, except for #3 and have tried several other combinations as well.

    If I ground the "inhibit in" pin I get a green light, but that should be disabling the output of the drive. I have been told that I need to ground this pin to make it work, but according to the datasheets this should stop, not enable the drive.

    I've tried several servo motors, and no change.

    Is there another way to test these drives? The last 2 came from a very recent ebay auction and are guaranteed not dead on arrival, so I'd like to figure this out quick. Seems unlikely that all three would fail and act exactly the same - am I doing something wrong? Any help is appreciated!

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    Default Re: Need Help with Advanced Motor Controls 25A20 drives

    Pretty sure those drives have an assembly time (solder) option to invert the enable function



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    Default Re: Need Help with Advanced Motor Controls 25A20 drives

    panozeng,

    According the the manual you are correct, the ground on the Inhibit pin should enable the drive, however they do suggest there is an engineering not on how to invert these inputs. Check out that note, perhaps the previous owner wanted inverted inputs.

    Russ


    http://www.kato-engineering.de/amc/Analog_B/30a8.pdf

    Pin-11 INHIBIT
    This TTL level input signal turns off all four power devices of the "H" bridge drive when pulled to ground. This inhibit
    will cause a FAULT condition and a red LED. For inverted inhibit inputs; see the Engineering and Installation notes
    on the Advanced Motion Controls website.
    Pin-12 +INHIBIT
    Disables the amplifier for the "+" direction only. This inhibit will not cause a FAULT condition or a red LED.
    Pin-13 -INHIBIT
    Disables the amplifier for the "-" direction only. This inhibit will not cause a FAULT condition or a red LED.



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    Default Re: Need Help with Advanced Motor Controls 25A20 drives

    Quote Originally Posted by panozeng View Post
    I have acquired 3 25A20 brushed servo drives for a LinuxCNC conversion, but I am not having any luck getting them to work. They appear to be very simple to connect; HV power in, power out to the motor, 2 tachometer wires. At that point I would think it should try to lock the shaft when powered on without any other inputs connected. Instead I get a red light indicating a fault. I have the dip switches all off, except for #3 and have tried several other combinations as well. If I ground the "inhibit in" pin I get a green light, but that should be disabling the output of the drive. I have been told that I need to ground this pin to make it work, but according to the datasheets this should stop, not enable the drive. I've tried several servo motors, and no change.

    Is there another way to test these drives? The last 2 came from a very recent ebay auction and are guaranteed not dead on arrival, so I'd like to figure this out quick. Seems unlikely that all three would fail and act exactly the same - am I doing something wrong? Any help is appreciated!

    I am using a 16AC20ACT drive for my NovaTurn refit. If your drive is an analog drive you will need a +-10V signal. To test the drive connect power, reset all dip switches as shown in the manual(pdf). You can use a 9v battery and a variable resistor to test the drive. The drive will show a green light when it is enabled, PIN 11. PINS 4 and 5 will be the +-10V input, you only need to drive one side to check operation, START at a LOW Voltage setting. Leave the tach open for testing and also PINS 12 & 13. I may be able to pull up some old pictures /video when testing my set-up.

    Hope this helps, Iron-Man



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    Default Re: Need Help with Advanced Motor Controls 25A20 drives

    I have used these drives for decades and found no real problem, I have the original hard copy of the catalogue and engineering manual set up for all the DC and BLDC drives.
    One note is that inputs INH and +/- INH can be inverted by removing J1 jumper (0 ohm SMT resistor) marked on the PCB.
    I control with a ±10vdc analogue signal.
    You don't need tach to test, in fact the only time you require tach feedback is open loop operation, otherwise with closed loop, you normally use current (torque) mode.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Default Re: Need Help with Advanced Motor Controls 25A20 drives

    It was the inhibit invert. I never could find a spec sheet with the suffix these drives had to see what it meant. Apparently the invert was part of the spec. What I didn't think about until doing more reading was that the inhibit invert switches all 3 inhibits - the main one and the positive and negative directional ones. If the resistor is missing at the spot labelled J1 on the board you then have to ground all 3 inhibits to get the drive to work.

    Thank you for the info!



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    Default Re: Need Help with Advanced Motor Controls 25A20 drives

    If the resistor is missing you can carefully use a small piece of copper wire and solder that where the 0 ohm resistor was supposed to be installed and it should reverse them back to active low.

    Russ



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Need Help with Advanced Motor Controls 25A20 drives

Need Help with Advanced Motor Controls 25A20 drives