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Thread: Jobo CPP2 Motor Malfunction

  1. #21

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    Feb 2008
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    Re: Jobo CPP2 Motor Malfunction

    Indeed Jim, I saw a stalling motion from the motor on my CPA2 late last week and decided to bite the bullet and remove it to see if i could delay the inevitable.

    I removed the motor completely and cleaned out both the gearbox and motor using automotive brake cleaner. Then i lubricated the motor brushes and commutator with electrical contact cleaner. I cleaned all the old grease out of the gearbox and replaced it with white grease, then reassembled it.

    So far, things seem to be good, the stalling has gone, so here's hoping.

    Mike

  2. #22

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    Aug 2000
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    Re: Jobo CPP2 Motor Malfunction

    Mike that is probably the most informative message in this thread. Thank you.

  3. #23

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    Re: Jobo CPP2 Motor Malfunction

    Thanks Jim.

    FYI, it's a 24 volt DC motor with a worm gear driving a single large reduction gear for the output shaft.

    It "looks" like a windscreen wiper motor. If push comes to shove, i'll try a used motor from a scrapyard.

    Mike

  4. #24
    Jim Korpi
    Join Date
    Jan 2016
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    Athens, Ohio
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    14

    Re: Jobo CPP2 Motor Malfunction

    Quote Originally Posted by mpirie View Post
    Hi Jim, If you're in the US, then your nominal mains voltage is 110VAC.

    I would avoid hard-wiring the transformer to the mains as there may be line conditioners etc cleaning the supply before it reaches the transformer.

    Changing the wiring may lead you down the wrong track, so best keep the wiring as designed by Jobo and fault trace from there.

    Again, be careful......if you are unsure, don't mess about with this stuff, it can kill you.

    Mike
    Hey Mike.
    So I've put my transformer back in the unit after it seemed to test fine. I then hooked everything back up, except I unplugged the motor from the motor board before turning the power on to the unit. I then turned the unit on and then then the motor switch. The motor fuse blew again. I figured that because I removed the motor wires from the motor board the problem can't be the motor itself but something down the line.
    I tested the switch that makes the motor go one way and then the other and it seemed fine. There is not much to it. Do you think the problem could lie in the motor switch/dial itself, the one that goes from 0-7? If so, how would I diagnose that? I'm running out of gumption here.
    Curiously,
    Jim Korpi

  5. #25

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    Feb 2008
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    Re: Jobo CPP2 Motor Malfunction

    H Jim, So if the unit behaved with the motor disconnected then blew a fuse when you reconnected the motor, then to me, that points to the motor causing a short.

    If you can get the motor out and open the gearbox to remove the reduction gear, you should be able to turn the motor shaft worm-gear by hand. If you can't turn the shaft, then the motor's seized.

    Before you remove the motor, make sure it's disconnected from the two spade terminals and try your ohm-meter across the motor green and black cables. there should be a small resistance. If there is no resistance, then you have a short in the motor. If you have a very high resistance, you have an open circuit and the motor's goosed.

    Regards,
    Mike

  6. #26

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    Dec 2014
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    Re: Jobo CPP2 Motor Malfunction

    Quote Originally Posted by jkorpi View Post
    Hey Mike.
    So I've put my transformer back in the unit after it seemed to test fine. I then hooked everything back up, except I unplugged the motor from the motor board before turning the power on to the unit. I then turned the unit on and then then the motor switch. The motor fuse blew again. I figured that because I removed the motor wires from the motor board the problem can't be the motor itself but something down the line.
    I tested the switch that makes the motor go one way and then the other and it seemed fine. There is not much to it. Do you think the problem could lie in the motor switch/dial itself, the one that goes from 0-7? If so, how would I diagnose that? I'm running out of gumption here.
    Curiously,
    Jim Korpi
    So you unplugged the motor from the MOTHERBOARD? I took electronics in 9th grade, so consider that before you take my advice. It's a DC motor, so I am assuming that the 0 to 7 switch is a "dimmer" . If the speed switch is working it should show variable resistance, I would think. If the motor is unplugged it shouldn't be the motor. Some how you need to get 24V (or less) DC to the motor without anything else in the way to see if it turns. My first thought was 16 AA cells lined end to end, but only I'm that crazy. You can do anything as long as you keep line voltage OUT of the picture. I wouldn't be surprised if a 9V transistor battery wouldn't move the motor slightly under no load.
    That speed switch should dim a test light, and should show a change in Ohms as you turn it. If it's shorted, i.e. conducting electric current without any effect that could be your problem.

    Remember my training consisted of building a tachometer for my '65 Chevy Biscayne with a 230 cu in 6 cylinder.

  7. #27
    Jim Korpi
    Join Date
    Jan 2016
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    Re: Jobo CPP2 Motor Malfunction

    Quote Originally Posted by Duolab123 View Post
    So you unplugged the motor from the MOTHERBOARD? I took electronics in 9th grade, so consider that before you take my advice. It's a DC motor, so I am assuming that the 0 to 7 switch is a "dimmer" . If the speed switch is working it should show variable resistance, I would think. If the motor is unplugged it shouldn't be the motor. Some how you need to get 24V (or less) DC to the motor without anything else in the way to see if it turns. My first thought was 16 AA cells lined end to end, but only I'm that crazy. You can do anything as long as you keep line voltage OUT of the picture. I wouldn't be surprised if a 9V transistor battery wouldn't move the motor slightly under no load.
    That speed switch should dim a test light, and should show a change in Ohms as you turn it. If it's shorted, i.e. conducting electric current without any effect that could be your problem.

    Remember my training consisted of building a tachometer for my '65 Chevy Biscayne with a 230 cu in 6 cylinder.
    Hey.
    Great response. Thanks for your thoughts.
    So, I have unhooked the motor from the motor board and then powered up the unit. The fuse still blew without the motor hooked up, so that tells me it's not the motor. I hooked the motor up to a variable DC power unit and was able to give the motor the exact DC power required to turn the motor, and VIOLA! It turned. So the motor seems good to go. I must say, the motor is hard to turn by hand. I can turn it, but it takes some umf!
    My next step is taking the speed switch out and testing it. I'm not sure how to hook it up to a light or what I should do to test it, but I'm sure I'll find some video on the world wide web.
    I'll let you know how it goes.
    Cheers,
    Jim

  8. #28
    Jim Korpi
    Join Date
    Jan 2016
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    Athens, Ohio
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    14

    Re: Jobo CPP2 Motor Malfunction

    Quote Originally Posted by mpirie View Post
    H Jim, So if the unit behaved with the motor disconnected then blew a fuse when you reconnected the motor, then to me, that points to the motor causing a short.

    If you can get the motor out and open the gearbox to remove the reduction gear, you should be able to turn the motor shaft worm-gear by hand. If you can't turn the shaft, then the motor's seized.

    Before you remove the motor, make sure it's disconnected from the two spade terminals and try your ohm-meter across the motor green and black cables. there should be a small resistance. If there is no resistance, then you have a short in the motor. If you have a very high resistance, you have an open circuit and the motor's goosed.

    Regards,
    Mike
    Mike,
    The fuse blew when the motor was unplugged from the board.
    I had unhooked the motor from the motor board and then powered up the unit. The fuse still blew without the motor hooked up, so that tells me it's not the motor. I hooked the motor up to a variable DC power unit and was able to give the motor the exact DC power required to turn the motor, and VIOLA! It turned. So the motor seems good to go. I must say, the motor is hard to turn by hand. I can turn it, but it takes some umf!
    My next step is taking the speed switch out and testing it.
    I'll let you know how it goes.
    Cheers,
    Jim

  9. #29

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    Feb 2008
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    Re: Jobo CPP2 Motor Malfunction

    Ah, ok Jim, i read your post wrong.

    As Duolab says, the speed knob is just a dimmer, allowing more or less current to the motor to change it's speed, though it also has a switch so that the motor can be turned off completely.

    Blowing fuses is a sign of a short. First place to start is to make sure all the wires are in the correct places....hard to do when we can't get a circuit diagram. Did you check the heating element for resistance/short?

    Mike

  10. #30

    Join Date
    Aug 2005
    Location
    Illinois
    Posts
    31

    Re: Jobo CPP2 Motor Malfunction

    They probably said "DC Rectifier". These would be a couple (or 4, depending on the transformer wiring) of diodes (or a single package of diodes) that rectify the AC from the transformer into DC for the motor/speed control. You'll probably find these at the output of the transformer along with a couple of capacitors. And yes, if one or more of these are shorted then you'll get a blown fuse.

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