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  1. #1
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    Permanent Magnet DC Treadmill Motor

    Wondering how I'd troubleshoot this motor that occasionally doesn't want to start, what I should be seeing in the way of DC voltage as more speed is called for and how they basically work in conjunction with the board. Didn't find much useful info after an hour or so on the net; other than where to buy them for too damn much when I don't even know if it's the motor. The closest I come to DC and motors are ECMs; but they have line voltage to the module and are controlled by DC voltage. I can't relate to this guy at all.

    Cambridge Motor Works
    Model JM01-011
    Volts DC 90
    RPM 3200
    Amps 21
    Continuous duty DC permanent magnet
    2.5 HP

    So we have 110 AC to the board and then what? It's converted (inverted? That's typically DC to AC?) to DC and sent to the motor? Does it deliver more DC voltage as more speed is called for? My hvac meters will only do microamps dc and not nearly on a large enough scale to handle something as large as 21 amps DC. So may I simply, using watts as a constant; just figure DC amps using ohms law once I have the AC watts?

    Can't find any detail or schematics re: the components that would typically shed some light...

    It's working at the moment. In the past the deck would just have to be waxed. But the other day it acted like it didn't want to go even with help. Just hummed. I popped the hood and immediately went to vacuum the crud out, disconnecting power and using the dedicated plug for the wet/dry vac. In doing so I guess I rebooted it and it came back to us. When it was hesitating you could clearly hear a relay click on the board, so I figured I'd be looking at voltages from the board to motor or the motor itself if it happens again.

  2. #2
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    Quote Originally Posted by hurtinhvac View Post
    Wondering how I'd troubleshoot this motor that occasionally doesn't want to start, what I should be seeing in the way of DC voltage as more speed is called for and how they basically work in conjunction with the board. Didn't find much useful info after an hour or so on the net; other than where to buy them for too damn much when I don't even know if it's the motor. The closest I come to DC and motors are ECMs; but they have line voltage to the module and are controlled by DC voltage. I can't relate to this guy at all.

    Cambridge Motor Works
    Model JM01-011
    Volts DC 90
    RPM 3200
    Amps 21
    Continuous duty DC permanent magnet
    2.5 HP

    So we have 110 AC to the board and then what? It's converted (inverted? That's typically DC to AC?) to DC and sent to the motor? Does it deliver more DC voltage as more speed is called for? My hvac meters will only do microamps dc and not nearly on a large enough scale to handle something as large as 21 amps DC. So may I simply, using watts as a constant; just figure DC amps using ohms law once I have the AC watts?

    Can't find any detail or schematics re: the components that would typically shed some light...

    It's working at the moment. In the past the deck would just have to be waxed. But the other day it acted like it didn't want to go even with help. Just hummed. I popped the hood and immediately went to vacuum the crud out, disconnecting power and using the dedicated plug for the wet/dry vac. In doing so I guess I rebooted it and it came back to us. When it was hesitating you could clearly hear a relay click on the board, so I figured I'd be looking at voltages from the board to motor or the motor itself if it happens again.
    The AC would be rectified to DC via diodes or SCR'S (diode with a third "gate" lead).
    In fact, I would think that would be a good way to control the speed.

    Does that motor still have brushes?

    Need a schematic.

  3. #3
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    Thread Starter
    Quote Originally Posted by IRBH View Post
    The AC would be rectified to DC via diodes or SCR'S (diode with a third "gate" lead).
    In fact, I would think that would be a good way to control the speed.

    Does that motor still have brushes?

    Need a schematic.
    Gotcha...thanks. Don't know about the brushes...At the moment it's still working - so I'm not taking it apart.

  4. #4
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    SCR diodes sounds a lot like a transistor.
    Quote Originally Posted by IRBH View Post
    The AC would be rectified to DC via diodes or SCR'S (diode with a third "gate" lead).
    In fact, I would think that would be a good way to control the speed.

    Does that motor still have brushes?

    Need a schematic.

  5. #5
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    Quote Originally Posted by lytning View Post
    SCR diodes sounds a lot like a transistor.
    lytning, they are similar.
    Transistors are 3 layer NPN or PNP-doped material, SCR family has 4 layers.

    SCRs can change AC to variable V DC.
    By using a reversed pair, it can supply AC at full peak voltage but chopped wave duration.

  6. #6
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    It will be interesting to know if it had brushes or was just Iq brushless DC.

    one mill in a shop at the feed table was SCR and had brushes and the position of the brushes adjusted by a couple screws on the end bell made it a little slower and stronger or faster and weaker (torque).

    But the rework , after coming back from a motor shop, left the brush position such that the motor hunted and radically jumped to medium and back to low rpm's -
    something about the feed back or back elect motive force emf of such a beast/ interfering with the controller to the SCR.


    ECM Brushles? Sometimes at low power they want to flop back and forth a couple degrees of rotation to seek a starting ?direction? and then take off... I do not know what a lot of starting drag, friction, may do towards not starting.

    We have had a few wiring harness plugs making poor high voltage contact on name brands using pins that can have locking barbs that are too squashed in their placement and needed repositioning in the plug male side.
    Process cooling: NO COMPRESSORS Earth-Coupled since 1996
    ... however, much still needs to be hybridized energy transfer.

    CLOSED LOOP 2015 listed EER's
    even 49+ now; and "blended from low to high variable speeds" for 32deg.F ~ E-Star

    Perhaps you need a 32F Chiller/HW-Heat: buy a GEO-T Heat Pump (GHP with Heat-Recovery)
    http://www.energystar.gov/index.cfm?...mal_heat_pumps

    http://www.hydro-temp.com/products.html and Bosch/Carrier and AquasystemsInc.com

  7. #7
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    Thread Starter
    Quote Originally Posted by GT1980 View Post
    It will be interesting to know if it had brushes or was just Iq brushless DC.

    one mill in a shop at the feed table was SCR and had brushes and the position of the brushes adjusted by a couple screws on the end bell made it a little slower and stronger or faster and weaker (torque).

    But the rework , after coming back from a motor shop, left the brush position such that the motor hunted and radically jumped to medium and back to low rpm's -
    something about the feed back or back elect motive force emf of such a beast/ interfering with the controller to the SCR.


    ECM Brushles? Sometimes at low power they want to flop back and forth a couple degrees of rotation to seek a starting ?direction? and then take off... I do not know what a lot of starting drag, friction, may do towards not starting.

    We have had a few wiring harness plugs making poor high voltage contact on name brands using pins that can have locking barbs that are too squashed in their placement and needed repositioning in the plug male side.
    Good to know...thank you.

  8. #8
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    Quote Originally Posted by GT1980 View Post
    It will be interesting to know if it had brushes or was just Iq brushless DC.

    one mill in a shop at the feed table was SCR and had brushes and the position of the brushes adjusted by a couple screws on the end bell made it a little slower and stronger or faster and weaker (torque).

    But the rework , after coming back from a motor shop, left the brush position such that the motor hunted and radically jumped to medium and back to low rpm's -
    something about the feed back or back elect motive force emf of such a beast/ interfering with the controller to the SCR.


    ECM Brushles? Sometimes at low power they want to flop back and forth a couple degrees of rotation to seek a starting ?direction? and then take off... I do not know what a lot of starting drag, friction, may do towards not starting.

    We have had a few wiring harness plugs making poor high voltage contact on name brands using pins that can have locking barbs that are too squashed in their placement and needed repositioning in the plug male side.
    GT1980, if you attempt to trigger a SCR at or past the sine wave peak, it may become unstable or no longer control.
    The simplest potentiometer from anode to gate speed control loses control past the AC wave peak.
    This sounds like the condition that you describe.

    Sorry for the derail.

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