Hammond M2 Run Motor Won't Engage

[andycecarelli]

Hello! I'm looking for some help regarding an M2 I picked up a few months ago. I got it home and oiled it (it had not been oiled or played in 8 years) and after about two days of allowing the oil to soak in, I attempted to start it. The start motor got the TG up to speed and I was able to play notes with the vibrato both on and off. The problem I'm having is when I flip the start switch off, the run motor won't take over.

The TG spins freely and takes about 20 seconds to come to a complete stop, the valves on the amp glow when the run switch is on, and the 250 ohm load resistor tests at about 290 ohms. When the run switch is on and I spin the TG by hand, the flywheel doesn't have the magnetic flip-flop of an electric motor so I am assuming there is a problem with powering the motor.

I've read many posts on similar issues and how to troubleshoot them, and after many attempts at fixing the issue I have still been unsuccessful. I was hoping to get dome more advice on this problem before going to a technician. Thank you so much!

[David Anderson]

If you turn the Run switch on without starting the generator and then turn the TG flywheels by hand, you should feel a magnetic resistance to turning the flywheels. If you don't feel this, then it's most likely one of two possibilities: Either 1) AC power is not getting to the Run motor, or 2) Your Run motor is bad, possibly from an open winding.

[tmccann]

A quick test would be to disconnect the two springs connecting the flywheel for the run motor to the tone generator. With these disconnected, and the power off, the run motor should spin freely and also slide a bit in an out along the shaft. If it doesn't spin freely or slide in and out some, it needs to be freed up with contact cleaner and working it by hand. In extreme cases I've had to remove the run motor from the TG to work it enough to break free. Watch the oiling thread on the front of the motor and that you don't break it with your fingers.

If the run motor spins freely, then turn on the run switch by itself. Now the run motor should be hard to turn due to the field being energized. If it spins freely then you have a wiring problem or a bad run motor.

[andycecarelli]

After trying both tests, I found that the flywheel will spin freely with the power both on and off. Is there way for me to test if the motor is receiving power? Thank you so much for your time and help.

[David Anderson]

Find and download the M-100 M-3 M-2 M Service Manual and find the relevant wiring diagram for the M-2. Look for the Line Panel and the terminals where the Run Motor leads attach. Remove the metal cover on the Line Panel. With the Run switch on, see if there is 120VAC across these terminals. There is 120VAC live on some of these terminals whenever the organ is plugged in. If you do not know how to take voltage measurements or don't feel comfortable doing it safely, hire someone to do it for you or get someone who knows how to do it to help you.

[tmccann]

David’s advice is spot on with the exception that on the M2 there is no cover on the line panel once the generator dust cover is removed. The line panel is exposed and as David says some terminals are live all the time so caution is in order. If you are not comfortable poking around live AC voltages then please get some help. AC voltage is no joke.

In the photo below I’ve circled the two terminals that power the run motor. If the run switch is on then you should be able to measure the AC line voltage with a meter and here in the U.S. you would measure 120V AC across those terminals. If there is 120V AC across those terminals and the motor spins freely you have a bad run motor.

if there is no voltage when the run switch is on then the run motor is likely fine and you have a run switch or wiring problem.

[David Anderson]

Good catch. I don't work on that many spinets.

[tmccann]

M100 and later spinets have the line covers.