Columbia Period Model Adam motor help please

[Victrola-Monkey]

I recently purchased this nonworking ultra rare (right?) phonograph and have found an open in the motor side resistance bar of the retangular two-bar component connected to the motor. In attempts to check the operation of the motor I just ran it direct to 120V. Got nothing. The motor (Model O) spins freely by finger and looks to be well lubricated. Any suggestions on what next things I should do to determine the fault and possibly the repair of the motor (and for the resistance bar)? Should I insert some sort of resistor between the motor and power when testing it? Thanks.

[ChuckA]

I recently purchased this nonworking ultra rare (right?) phonograph and have found an open in the motor side resistance bar of the retangular two-bar component connected to the motor. In attempts to check the operation of the motor I just ran it direct to 120V. Got nothing. The motor (Model O) spins freely by finger and looks to be well lubricated. Any suggestions on what next things I should do to determine the fault and possibly the repair of the motor (and for the resistance bar)? Should I insert some sort of resistor between the motor and power when testing it? Thanks.

Universal motors usually work on low voltage AC/DC supplies, 30-35 Volts.

Check resistance of the power resistors. Should be in the 200 to 500 ohm range for each. If open you can replace with a 25 - 50 watt ceramic, you can get these from Allied Electronics.

Next is to check the carbon brushes make sure they are making contact with commutator. If none of this helps you may have an open windings.

Chuck

[Victrola-Monkey]

Thanks Chuck. Things at the commuter and rotor test good. Then I checked the resistance of the two wires leading into the motor. That should have been my first test. Unfortunately there's an open between the two wires where there should be continuity. Like to test the two ends of the coil where those two wires connect inside the casing. Guess the motor is requiring disassembly at this point.

[Victrola-Monkey]

Well, good news Chuck. Just a bad bend in the wire right before the motor. The motor leads test to be 175 ohms between them. The Resistor Block is bad, both resistance bars, but at least looks nice and it's good to have it. After checking on two resistors at each end of the range you suggested and getting a price of $27 total with shipping and handling, I decided to run to Radio Shack. With limited availability I gathered up four 50 ohm (10W) ceramic block type resistors and put them in series just for a quick test. Motor spun, test complete. Wondering if I should spend the $27 to order the 2 Allied resistors or settle with multiple $1.25 resistors, or even add more? Thanks -Wayne

[ChuckA]

Well, good news Chuck. Just a bad bend in the wire right before the motor. The motor leads test to be 175 ohms between them. The Resistor Block is bad, both resistance bars, but at least looks nice and it's good to have it. After checking on two resistors at each end of the range you suggested and getting a price of $27 total with shipping and handling, I decided to run to Radio Shack. With limited availability I gathered up four 50 ohm (10W) ceramic block type resistors and put them in series just for a quick test. Motor spun, test complete. Wondering if I should spend the $27 to order the 2 Allied resistors or settle with multiple $1.25 resistors, or even add more? Thanks -Wayne

Wayne,

Just measure the voltage at the motor terminals if it measures around 32volts you're good, fine tune the resistors to get the voltage in the 30-35volt range.

They will be under the cover so no one will notice you made up the resistance from multiple units.

Chuck

[Victrola-Monkey]

Chuck,

The original 200 ohms had it running 94v but when I added another 200 ohms, it stopped running and was at 74v. Note the original resistor block has two labeled positions to set the adjustable wiper, 110vdc and 110vac. Any chance this motor runs in 110vac versus 35vac?

-Wayne

[ChuckA]

Chuck,

The original 200 ohms had it running 94v but when I added another 200 ohms, it stopped running and was at 74v. Note the original resistor block has two labeled positions to set the adjustable wiper, 110vdc and 110vac. Any chance this motor runs in 110vac versus 35vac?

-Wayne

I haven't worked on a Columbia universal motor in awhile, and was just going on memory. So, with that information it is wound for 110v operation. The best would be finding someone with one of the art models with the universal motor and have them check the resistance in a working unit. The other option is to set the resistance to run it at the lowest voltage that keeps constant speed when playing a record. Sorry I can't be more specific.

Chuck

[Victrola-Monkey]

Thanks again Chuck, for your info and guidance.

If anyone has a 110 volt Columbia universal motor with a working resistor element, it would be great if you could measure the resistance between the two terminals and post it here. A simpler way would be to have the Grafonola on and in play, with the lid closed (closed to disconnect the bulb), then unplug the machine. Then, measure the resistance between the two prongs on the plug. My Model O on the above pictured Adam gives a total unplugged measurement of 370 ohms, whereby my temporary four 50 ohm resistors take up 200 ohms of it and wiring/switches take up zero. I've ordered a single resistor to replace the multiples.

Note that the Gothic model seen previously on eBay also has its resistance element bypassed.