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B&O Beogram 1900 bad motor?

Discussion in 'Troubleshooting and Repair' started by KilgoreCemetery, Mar 5, 2018.

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  1. KilgoreCemetery


    Apr 12, 2017
    I recently picked up this turntable for cheap, but the motor won't spin. I opened it up and realized that someone had already been playing with the wiring a bit, and after looking at the wiring diagram, I wasn't sure it was even connected right. The wire colors don't match what it says on the schematic, so that makes it extra confusing, but when I had finally decided I had it all figured out, the motor still doesn't spin.

    Here's what it looked like when I first got it:

    And here's the schematic:

    Since then, the bearings have been cleaned, oiled, and I'm able to spin the rotor freely with my fingers. The resistor and capacitor both tested ok and I cleaned the contacts on the switch mechanism. Also, while I was trying to figure out how the motor wires were supposed to be connected, I did a resistance check with the wires unhooked.

    Black - Blue = 327.4 Ohms
    Red - Yellow = 331.6 Ohms

    Every other combination showed no connection. I have no idea what the resistance is supposed to be, but I figure the electricity has to go somewhere. So, I decided that the Green wire that is mentioned in the schematic must actually be Black, and the Brown one is Red.

    Here's what I came up with:

    This may provide more information as it shows how the wires connect to the motor:

    So far, no combination has gotten anything more than a hum from the motor. Is there a quick test to show whether or not the motor is good? Any information would be helpful at this point
  2. kellys_eye


    Jun 25, 2010
    Trace out the wiring as YOU have done it and derive a wiring schematic from it that we can look at.

    The photo's you show don't have enough information - i.e. can;t see the wires to the motor coils, can't see the contact arrangement under the white block etc.
  3. duke37


    Jan 9, 2011
    I have never dealt with a motor lke this.
    330Ω seems reasonable.
    Is the motor supposed to reverse?
    The two windings are in series with 55V across each, 117v total.
    I think the resistor and capacitor are there to suppress interference when switching.
    Connect the two windings in series and to nothing else, see if the motor runs.
    If it doesn't, swap one winding over.
  4. Alec_t


    Jul 7, 2015
    If a rubber pinch/drive wheel or belt has disintegrated, is it possible that the motor is spinning but simply not driving anything? Can you tell if the actual motor shaft is rotating?
  5. KilgoreCemetery


    Apr 12, 2017
    Hey, thanks for the replies! I don't have time at the moment to draw up a wiring schematic, @kellys_eye, but I'll look into it on Sunday evening.

    @duke37 I don't think reverse is an option, but I'm guessing the motor is supposed to be able to do two different speeds. I don't remember if it has two different drive wheels or not off the top of my head. To the best of my knowledge, it is connected in series. Running some fresh wire and bypassing all the additional contact points sounds like a good idea though.

    @Alec_t That's a good thought. I actually took it apart to test it. The belt is unhooked and I'm able to see the bottom of the motor while it should be spinning. I've even tried giving it a little boost. Nothing..
  6. KilgoreCemetery


    Apr 12, 2017
    Ok, I've thought over the wiring schematic thing a few times now, and this is what I've come up with:

    Circuit Diagram Edit.jpg

    Which corresponds to the numbers on here:


    And this picture makes it easier to tell what wires connect through the motor:


    Black -> Blue = 327.4 Ohms
    Red -> Yellow = 331.6 Ohms
    Any other combination -> 0.L

    I also went through and disassembled, cleaned, and reassembled all the electrical switch parts. With everything resoldered, and the switch closed (Play mode), I'm getting about 0.3 ohms between junctions 2 and 4. I also get the same reading between junctions 2 and 4 while in Turn mode. These modes are shown in the wiring diagram. Basically, this tells me that the wiring diagram and the mechanical part of the turntable match and that I'm getting good connections all around.

    While everything was desoldered, I also tried bypassing the multiple contact points by wiring the motor directly to a power cord, but still no luck.
  7. KilgoreCemetery


    Apr 12, 2017
    Are there any general AC induction motor tests that I could perform to make sure that the motor itself is working properly? Is there a common fault to check when they go bad? Do they really ever go bad?
  8. nepow


    Jul 18, 2011
    With the motor removed from the player, take the yellow of one winding and connect to either green or black of the other winding. You no have one red wire and one black wire... check resistance which should equal the combined resistances of each individual windings ( 6oo ohms or there abouts) You can now connect these two wires (red and black) to the AC supply. At this point please observe electrical safety while connecting to AC mains voltages use a length of flex to the motor connections and insulate accordingly. If the motor refuses to spin but clearly hums, you need to reverse ONE of the winding connections only, i.e. transpose say red and yellow.
    The switch breaks the series winding configuration in the off position. The only other thought! just check if the player has an AC voltage selector in which case your motor may be powered from a mains transformer rather from direct AC at 230v.
  9. KilgoreCemetery


    Apr 12, 2017
    Thanks for the input, nepow. That's about where I started, though, and I was still never able to get any spin from the motor. There is a voltage selector, but I'm pretty sure it's set correctly for my area. I think I'm just going to try to part out this player. It's not something I would actually want to keep around anyway.
  10. nepow


    Jul 18, 2011
    I used to work for a B&O HiFi dealer many moons ago. Seem to remember we had the occasional motor failure so maybe that's the fault?
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