Help me before I electrocute myself

Discussion in 'The Projects Forum' started by Donttaseme, Oct 17, 2010.

  1. Donttaseme

    Thread Starter New Member

    Oct 16, 2010
    5
    0
    I bought a really cool beat up old fan from the 1930s

    It was in working condition but as I cleaned the thing up I wanted to replace the cord since it was falling apart. I took apart the fan and removed the electric cord, the wires were attached directly to the coils.

    Now that I have attached a new cord it doesn't work. It seems like maybe the magnets might be pushing instead of pulling so I tried switching where the wires connected to but still nothing.

    Any help with this would really be appreciated Im feeling dumb about breaking something just got.

    I don't know what I'm doing and don't have the self restraint from trying anyhow. So any help could possibly be saving me from a death by electrocution.
     
  2. Dragonblight

    Active Member

    Aug 19, 2009
    35
    0
    Sounds like it's binding or that's a high-resistance connection.

    Multimeter your connection and see what it comes out with, just for kicks and giggles.

    Also, lube lube lube! Those ancient fans need tons of oil and grease to keep them going.

    Finally, Pics plz.
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Hello Donttaseme,

    Dragonblight's advice assumes a degree of familiarity and competence in electrical work.

    My advice is that you don't continue with this dangerous exercise.

    At that age the fan would need to be checked for both earth and insulation integrity.

    Remember you may not electrocute yourself but a family member or friend might be injured or killed if they touch an incorrectly wired appliance.

    Would you want someone else's death on your conscience?

    Take it to a qualified electrician.
     
  4. Donttaseme

    Thread Starter New Member

    Oct 16, 2010
    5
    0
    judging by the looks of it, the thing looks like its not suppose to be greased. The problem isn't lube, it spins just fine when the fan is off, but when its on it fights against being turned.

    here is what the thing looks like, ill take some pics of the motor when i can but it has 4 copper coils and the cord was connected directly to the coils

    http://www.worthpoint.com/worthopedia/roto-beam-electric-fan-cast-aluminum-prop-c-1935

    Thanks a ton btw guys I really want to get this thing working!
     
  5. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    I am pretty sure Dragonblight meant detailed pictures of the wiring.
     
  6. Donttaseme

    Thread Starter New Member

    Oct 16, 2010
    5
    0
    i know, here are some pics the pics
     
  7. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    I am not sure why you would have needed to disassemble it to this extent. I would say you may have damaged some of the wiring of the coils. If not then I would double check your original power cord and compare it with your new one. If it is a 2 wire cord it "should not" matter which way around they go as it is an AC signal.

    I still think you have done some damage to the coils or the connections to them.
     
  8. Donttaseme

    Thread Starter New Member

    Oct 16, 2010
    5
    0
    i had to take it apart to this extent just to get the old corroded power cord off.

    The power cord attached directly to the copper coils and absolutely needed to be replaced.

    It's definitely receiving power it's just that the magnets are making the blade resist moving rather than spin.

    Good point though with AC it doesn't matter what wire goes where. It's just strange because from what i gather this is how it would act if your messed up the wires on a DC current.

    Well I'm stuck, any ideas would be greatly appreciated.

    Thanks guys
     
  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,007
    1,530
    For the motor to not revolve like you're describing it sounds like one or more coils are not connected. Did you scrape the insulation/varnish off of your wires before soldering?

    Old small gage wires like used in these motors is sometime very brittle. It breaks from just being moved. Buy or borrow a multimeter and check for continuity between coils.

    If you have to or have, shortened wires from the coils, make sure you scrape the varnish from the ends where you will solder. Just lightly with a sharp knife or Xacto blade, or even fine sand paper. The solder heat won't remove it. If you don't do this there won't be electrical contact, even though the solder will encapsulate the wire.
     
  10. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,783
    943
    Are you 100% positive it is an AC motor?
     
  11. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You really should take the fan to a shop that rebuilds electric motors.

    Ancient lacquer (used for insulating that kind of wire) is very brittle and chips off easily. Old copper wire gets brittle, too. This will lead to shorts in the motors' windings and a possible electrocution hazard.

    A motor repair shop also has a tester called a "megger". The megger is used to ensure that the insulation won't break down under normal and even abnormal use (like when a voltage transient hits the power lines).

    This is for your own safety, and in the interests of preservation of a very interesting antique.
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    Pictures BEFORE you disconnected things would be more helpful! Can you measure resistance of each coil? Each coil should show continuity, with a measurable but low resistance. Hard to guess but 20-100 ohms per coil wouldn't surprise me. I think they're probably all the same, so it'd be nice to see similar values for all.

    I think the important thing in your case is that coils are directional with respect to each other - they need to work together. How sure are you that the only two connections you broke are the power mains? If you've had to repair other connections as well, they are all suspect of wrong "polarity". Not relative to AC, but relative to winding direction.

    BTW, in addition to electrocution issues, that fan is really dangerous to fingers, since you could stick your whole hand thru the grate. I've got the scars to prove that this can be a real hazard, especially to kids.
     
  13. Donttaseme

    Thread Starter New Member

    Oct 16, 2010
    5
    0
    how much do you think it would cost to take it in and get it fixed?
     
  14. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The more you attempt to fix it yourself, the higher the eventual tab will be.

    In any event, it will be far cheaper to have a pro fix it than a funeral, or losing your home to a fire.

    I love antique electrical stuff like that, too. However, they were designed at a time when safety wasn't really a top priority.

    A good motor repair shop will make sure that it's safe to operate. They have the tools and training to make certain it's safe. There really isn't a good way for us to convey all that you need to know across the Internet; the learning curve would be too steep, too long, and I simply don't have that much time.
     
  15. Hagen

    Active Member

    May 8, 2010
    30
    1
    When you say the motor resists turning when power is supplied, what this tells me is that most likley the bushings (and possibly the motor shaft) are worn to the to the point that when power is applied, the magnetic fields established just cause the rotor to be pulled against the stator iron, and drag.
     
  16. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    He has already said that the motor spins freely when unpowered.

    If he is now feeling some resistance when powered I would say one or more of the coils are open. Not knowing the wiring configuration its hard to point it out exactly.
     
  17. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    He needs to take it to a pro for evaluation.

    There is no way that we can convey all that our OP needs to know how to fix an antique mains-powered fan in less than a few weeks - but he'd still have to have a megger, and those are pretty expensive.

    I hope he does the right thing, and takes it to a pro. They'll make certain that it's safe, and it will probably cost a lot less than our OP might think. He will also learn a lot from seeing someone work on his fan, if they allow him to do that. If our OP has too many questions, they will probably toss him out; they have to get motors fixed. Best to ask for a brief demonstration of tools used, etc. when picking it up.
     
  18. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    I agree totally sarge. Nothing against the OP but I think we both agree the problem is now way past his experience level. It may cost him a few $ to fix but it may well be worth it. If he takes it to the right place he may even get a new power cord the replicates the original. If it is in a good condition it could be worth a lot more than he paid for it.
     
Loading...