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PM1440GT will not run

Discussion in 'PRECISION-MATTHEWS' started by dpb, Jun 10, 2017.

  1. dpb

    dpb United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I last used the lathe about 2-3 weeks ago, and it ran without issue. Today the motor will not run, using the apron motor control lever.
    This is a three phase machine, running on single phase & a Hitachi VFD, using Mark Jacob's basic, existing contactors conversion. I have many hours on it, without a hiccup.
    It will run in either direction, at what seems to be the correct reduced rpm, using the jog joystick I installed as part of the conversion.
    There are no obvious loose or disconnected wires in the electrical panel.
    I have ensured that the motor control lever is in the neutral (center) position when power is connected.
    The foot brake is not stuck, and appears to actuate the micro switch in the LH cabinet when depressed.
    The terminals on the electrical panel the foot brake micro switch leads are connected to, show ~26v regardless of the position of the brake.
    When the motor control lever is moved in either direction, there is a small click heard from the limit switch on the RH end of the bed.
    There is no other noise, motor hum, etc, when the control lever is actuated.
    No noise is heard from the forward or reverse contactors, where I feel that I used to hear a click on startup.
    The VFD is on, and shows 0.0 when not running, and 6.0 when the jog switch is used.
    The 3 internal fuses are not blown.

    What to look at next?

    Thank you.
     
  2. Atlascycle

    Atlascycle United States Iron Registered Member

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    Is there a factory E-stop on the machine? Or maybe a Interlock for a cover?

    Sent from my XT1254 using Tapatalk
     
  3. dpb

    dpb United States H-M Supporter - Premium Content H-M Supporter-Premium

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    There is an E-stop, as wired, the jog switch wouldn't work either, if the e stop was engaged. I will double check that wiring, but it should be fine.
    The are no cover interlocks that I am aware of, and the problem exists with all covers in place.
     
  4. mksj

    mksj Active User H-M Supporter-Premium

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    Is the power light on? if not, check the 5A fuse that supplies the 24VAC to the controls is not open. Check that there is 24VAC coming out of the transformer. If the power light is not on recheck the footbrake interlock is not stuck pushed in, and or the cam shifted. It is NC when not activated, you may need to check it with an ohm meter.
    Check that the small 24VAC relay by the transformer has the red light on.
    If the 24VAC relay light is on, then check the spindle connection wires, 5, 6, 7, 8 that nothing came loose. You can also carefully probe them for 24VAC,
    I am not sure how you have the Jog wired, is it directly activating the VFD or does it use the old Jog wire connections (i.e. activates the forward contactor).
    The forward and reverse contactor should operate when you engage the spindle switch, check and see if the contactors are being activated. If not you will need to work backwards with a 24VAC voltmeter to see where power is being interrupted.
    1440gt fuse.jpg
     
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  5. dpb

    dpb United States H-M Supporter - Premium Content H-M Supporter-Premium

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    If the relay light is the red item in the lower left of the relay, it is not on. The jog directly activates the vfd.
     
  6. dpb

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    The 5 amp fuse is not blown.
     
  7. dpb

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    Connection 5: 24v, 6: 21v, 7: 32v, 8: 32v
     
  8. dpb

    dpb United States H-M Supporter - Premium Content H-M Supporter-Premium

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    The transformer shows correct, or close, voltages when read from the transformer terminal to the 0v transformer terminal. It shows strange voltages when read from terminal to the lathe stand, 137, 56, 45, & 33, for the four terminals, starting with the 110 terminal.
     
  9. Atlascycle

    Atlascycle United States Iron Registered Member

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    My assumption is the stock contactors are closing the contacts for the frequency drive are you saying the contactors are not pulling in?

    Sent from my XT1254 using Tapatalk
     
  10. Atlascycle

    Atlascycle United States Iron Registered Member

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    If the stock motor contactor is closing the circuits for the frequency drive try manually engaging the stock contactors to see if it engages the Spindle.
    If that works check the common connection on the motor starter contactors and then work your way back through the control circuit.

    Sent from my XT1254 using Tapatalk
     
  11. dpb

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    Problem solved!
    Many thanks to Mark Jacobs, for his invaluable troubleshooting assistance.
    The foot brake limit switch is kaput, and has been temporarily bypassed.
    Thank you for your responses.
     
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  12. jer

    jer Active Member Active Member

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    I'm glad you got the GT back up and running. We are sure lucky to have some very smart people on this forum (aren't we!)
     

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