Roland RE-501 Motor parts

[smilan]

Hi, I have on the bench a RE-501. When I turned the unit on, the motor didn't run, so I took it apart for cleaning, I found this small thing inside the metal housing. I can't trace where exactly it was glued on the big black wheel. Does it matter where to re-glue it?

 

[RoadrunnerOZ]

Hard to tell with that photo as the tiny piece is a bit blurred but it may be one of the Hall sensors - these are attached to a PCB via 4 or more leads or a strip with solder pads differing depending on motor type - Nippon Densan or Pioneer and are fitted into the periphery of the motor board. You’ll need to dismantle the motor fully and have a good look. If you’ve lost a sensor the motor won’t run - you can’t just glue them back as they are an electronic component soldered in place and control the motor.

 

[RoadrunnerOZ]

This video might help:

 

[smilan]

This video might help:

Thanks, I saw this video, but this is a different type of motor, without those small things. Here's a picture of a 150 motor with the same part. It's hard to tell of there's only one or the other one is "hiding" just behind the shaft?

 

[RoadrunnerOZ]

Was the part attached to the magnet or the stationary PCB?

 

[RoadrunnerOZ]

The hall sensors in the pic you’ve shown there are buried in the poles of the stator windings with 4 leads running to each off the PCB. Not sure what the little piece attached to the magnet is but it may trip the sensors. The magnet is the rotor and the switching of the stator poles energising power transistors is done by the hall sensors.

 

[transient]

It's a while since I did one of those, but isn't it a balancing weight, for dynamic balance as with tire balancing on a vehicle? If so, look for the footprint of the original mounting and glue it back in the same place. If that's not possible, the motor will run without it, maybe with a little more vibration and W&F, assuming the electronic part is functional.

 

[RoadrunnerOZ]

That may well be the case that it’s a balance weight (looking at where the sensors are they would be in the middle of the magnet). If so there will be a glue bed the piece should mate with - a little high strength epoxy would hold it.
As for the motor not working that’s another story. You’ll need to check that the motor is getting the correct supply voltage, p9 of the service manual, also that the motor shaft moves freely and that the bearings haven’t seized.

 

[smilan]

It's a while since I did one of those, but isn't it a balancing weight, for dynamic balance as with tire balancing on a vehicle? If so, look for the footprint of the original mounting and glue it back in the same place. If that's not possible, the motor will run without it, maybe with a little more vibration and W&F, assuming the electronic part is functional.

That may well be the case that it’s a balance weight (looking at where the sensors are they would be in the middle of the magnet). If so there will be a glue bed the piece should mate with - a little high strength epoxy would hold it.

I can't trace any glue residue anywhere on the black wheel.

As for the motor not working that’s another story. You’ll need to check that the motor is getting the correct supply voltage, p9 of the service manual, also that the motor shaft moves freely and that the bearings haven’t seized.

After cleaning the shaft and the bearing the motor runs (without this part), but I would like to return it (if I only know where to put it...)
I guess I won't be able to spot the original place of this balancing weight, so I'll keep it outside the enclosure.

 

[RoadrunnerOZ]

Is there any discolouration on the lower edge of the magnet that would indicate something having been there? Also is there a totally smooth edge to the dislodged piece that would match the magnet periphery surface?
Also if the piece were to be fitted to the periphery would it clear the circuit board and wires below?