Identifying and replacing a small DC motor

[ryancparadiso]

Hi all

I am looking to source a specific mini DC motor for a paper collator tower. I have removed the motor, and attached pictures of it. The motor runs intermittently when in test mode, but sometimes sputters (turns a little, stops, tries to turn a little...), which trips the error system. When testing its wires for continuity, I consistently get a reading of 10-15, so it seems like there is some resistance. And, when I turn the spindle manually, it seems to get 'stuck' / find patches of physical resistance, though I'm not familiar with motors and so am not sure if this is normal or not.

All of the information I have about it, which is also on the picture, is:

DC Motor
Type SP
No. FM-36E
China | Fuji Micro
(and on the other side, a sort of serial(?) number: ID24 JSP)

measurements:

- body: 1.5 in diameter, 2 in. length
- spindle: 5/32 in. diameter, 1 in length

The company no longer supports this machine, and does not have any replacement motors. I have not been able to locate it online, and don't know enough about it to know what sort of new motor might work. Any help would be appreciated! Thank you so much~~

 

[Bluejets]

Do not see any photos.
However a search on ebay or aliexpress should turn up something that wuld be adaptable.
You'll need voltage and power rating .

 

[ryancparadiso]

Do not see any photos.
However a search on ebay or aliexpress should turn up something that wuld be adaptable.
You'll need voltage and power rating .

I just scoured the technical manual to find that it is 24 V, 0.46 A. Do you know how I might measure for power? or RPM?

 

[Delta Prime]

I just scoured the technical manual to find that it is 24 V, 0.46 A. Do you know how I might measure for power? or RPM?

Power in watts equals Voltage multiplied by Current.
P = V X I
P = 24 X 0.46
P = 11.04 Watts
The power of your motor is 11 watts,
The angular velocity of your motor shaft is measured in revolutions, per minute or RPM.
You can use tachometer sensor on the motor shaft directly to measure the rotational speed or use an encoder to give you one pulse per revolution of the motor shaft over a given period of time.
DC motor's speed is directly proportional to the input voltage. The higher the input voltage, the faster the output speed & is dependent on your load or what the motor is turning the force, it takes your motor to turn or twist the load, is called torque.

 

[Martaine2005]

Show a picture of the motor.
Does the motor mesh with a gearbox or planetary gears?.

 

[ryancparadiso]

Power in watts equals Voltage multiplied by Current.
P = V X I
P = 24 X 0.46
P = 11.04 Watts
The power of your motor is 11 watts,
The angular velocity of your motor shaft is measured in revolutions, per minute or RPM.
You can use tachometer sensor on the motor shaft directly to measure the rotational speed or use an encoder to give you one pulse per revolution of the motor shaft over a given period of time.
DC motor's speed is directly proportional to the input voltage. The higher the input voltage, the faster the output speed & is dependent on your load or what the motor is turning the force, it takes your motor to turn or twist the load, is called torque.

Ah, amazing! Thank you so much for this.

 

[ryancparadiso]

Show a picture of the motor.
Does the motor mesh with a gearbox or planetary gears?.

Oops, I thought I'd attached files. Here are a couple of the motor, and one showing its placement in the system. The motor is sort of hidden here, but circled in red—that black fan thing (which spins thru a sensor) is mounted on the motor's shaft. These all work to turn a long shaft attached to the top left gear, which turns a set of rollers, which send paper through the machines.

 

[Minder]

Does the motor run OK off the machine?
They are well made motors, if you DO have to replace it, look for ball bearing versions.

 

[Bluejets]

If motor details were clear and focused, it would be a big help.

 

[Martaine2005]

If motor details were clear and focused, it would be a big help.

Click on the photo, it will open.
It’s very clear

 

[Bluejets]

Click on the photo, it will open.
It’s very clear

I did.....made no difference.

 

[Delta Prime]

Click on the photo, it will open.
It’s very clear

1. That poor thing has age-related macular degeneration! The Amsler grid is a simple square containing a grid pattern and a dot in the middle. When used correctly—once a day, every day—the Amsler grid can show problem spots in your field of vision.
2. If you notice any areas of the grid that appear darker, wavy, blank or blurry, contact your ophthalmologist right away.
3. 
   
4. 
5. 
   
6. Wearing any glasses you normally use to read, hold the grid 12 to 15 inches away from your face in good light.
7. Cover one eye.
8. Look directly at the center dot with your uncovered eye and keep your eye focused on it.
9. While looking directly at the center dot, notice in your side vision if all grid lines look straight or if any lines or areas look blurry, wavy, dark or blank.
10. Follow the same steps with the other eye.
11. https://www.aao.org/eye-health/tips-prevention/facts-about-amsler-grid-daily-vision-test

 

[Martaine2005]

This is what I see by clicking the image.

 

[Delta Prime]

This is what I see by clicking the image

Then it is, I who should see the ophthalmologist. This is what I see by clicking the image.

 

[ryancparadiso]

Hi all, just want to revive this thread with some updates.

So, I sourced a few motors, none of which were perfect, but good enough to at least test with. I also cleaned and reassembled the original motor.

I tested the original and new motors via the machine's motor maintenance mode, and all of the motors reacted in the same way: they will run at full speed for 1-2 seconds, then drop down to a fraction of the speed for 1-2 seconds, then cut completely. And after that, I can't get them to start up again.

Does anyone have a theory as to what might cause this sort of motor behavior?

It seems that something upstream of the motor is the issue. The maintenance manual says, at this point, to check the conductance of the wires, and then replace the entire circuit board (which would cost more than I paid for the entire machine in the first place...). I've removed the circuit board and am going to go over it with a magnifying glass to check for any cracked solders etc, and then maybe go through the entire machine and clean every single wire connector I can find and re-seat them. Any other ideas?

Thank you all so much, you've been a huge help~~

 

[Delta Prime]

It seems that something upstream of the motor is the issue. The maintenance manual says

Care to share the maintenance manual or make, model of your machine, please.& your manual?

Does anyone have a theory as to what might cause this sort of motor behavior?

Yes. it’s old!
We have to make some voltage measurements on your PCB board. I would not touch anything mechanical ,you’re gonna make it worse than it already is, but I do admire your zeal. Tell us the make & model of your machine and wait for a response please.
The free troubleshooting advice you are getting is an order of magnitude more than the price you’ll pay for the machine or the PCB because your advice-is free.

 

[ryancparadiso]

Care to share the maintenance manual or make, model of your machine, please.& your manual?

Yes. it’s old!
We have to make some voltage measurements on your PCB board. I would not touch anything mechanical ,you’re gonna make it worse than it already is, but I do admire your zeal. Tell us the make & model of your machine and wait for a response please.
The free troubleshooting advice you are getting is an order of magnitude more than the price you’ll pay for the machine or the PCB because your advice-is free.

.........


it's a Duplo DFC-12 collator tower

the service manual is too large to attach, but I'm happy to email it to you

 

[Harald Kapp]

The issue might be not with the motor but with the sensor. I see it as follows:
The "fan" is not a fan at all. It is is the encoder for the IR photoelectric sensor (post #7, rightmost image). The sensor's output is used to detect whether the motor is moving at the correct speed (or moving at all). Possibly (only a guess) the electronics starts the motor and checks for a valid sensor signal. If there is no signal or an invalid signal, the electronics first reduces the motor's speed, then shuts down the motor to prevent damage.

1. check the wiring from and to the sensor for continuity
2. check the sensor. Unless you have equipment to power the LED and check the photoreceiver side you may simply have to repalce the sensor with a new one.
3. check the sensor for any dirt or dust that may have accumulated in the slot and may block the light path between LED and sensor permanently (porbably the first thing to do). Do not be worried if you don't see ligt from the LED: it's invisible infrared.

When wiring and sensor are o.k., the issue is very likely with the controller board.

 

[ryancparadiso]

These tests were done in the machine's maintenance mode, which just tests the motor function in isolation. So, it was tested with a bare spindle, not connected to the drive belts etc. I have also run sensor tests in this mode, and the sensor for this motor is functioning. I should note, this same pattern is also what was happening as the unit began to fail, while properly connected to the drive belts and sensor engaged.

 

[ryancparadiso]

Here is a smaller file excerpted from the service manual, with relevant wiring information, specifically A-21-25