Motor Speed

Rotation speed is different on one of the motors.
After one hour of usage where everything was ok, suddenly one motor spinning slower than the other. The setup speed is the same. I changed positions with the cables for testing. The same motor is slower than the other one again.

What motors and what controller are you using?
And what are the motors driving?
Does that motor get hot?

It is the sts with explorer hat and raspberry pi 3.

No they are not hot at all.

They worked fine for about an hour at total. Now any time I start the system I have the some problem.

When you say “The same motor is slower than the other one again”, do you mean the motor on that same side is slower? Or the same motor moved to the other side is still slower than the other one? One indicates an explorer hat issue the other indicates a bad motor.
With the power off, if you turn the wheels with you fingers does one feel harder to move than the other?

What are you using for a power source?
If you power the Pi 3B+ with an official power supply does the same thing happen?
Just hold the STS in the air if you have too.

The problem is with the, let’s name it, motor2.

Even thought I move the motors from one side to the other the motor2 still has the same problem.

When I set the speed to 20 , holding the sts on the air, the motor 2 not spinning at all or very very slow. The other one works fine.

Ok, thanks for clarifying that, it sounded like the problem followed the motor but I wasn’t 100% sure. I’d say the motor failed? It sucks but it happens. How long have you had it? If you’ve had it more than a month you’ll likely just have to buy another motor.
There is a “contact us” link at the bottom of the Shop page to contact Pimoroni directly via e-mail.

If the wheel on that motor is physically hard to turn with you fingers. IE harder to turn than the other one, it might be the gearbox attached to the end. If you end up in a situation where you have to buy a new one I’d open up the bad one for a look see.

I received it on Wednesday 18/12. Bought from amazon. Order 306-4193546-3805159 (11/12/2019)

I’d say you’ll have to contact Amazon if thats where you purchased it from.

Ok. Thank you a lot for your help.

Because it is a big trouble for me to return the entire sts package back to amazon, is it possible to tell me the exact model of the motor? I want to order it separately.

According to the product page they are a Micro Metal Gearmotor with Push Header Shim – 298:1.

Check the one you have to make sure something didn’t get in the gears and is jamming them or something?

Yes the defective is harder to physically rotate it.

It might just be the gearbox thats jammed up. I wouldn’t throw it away, you may be able to remove the gearbox part and use the motor for something down the road.

It’s not the gearbox. I switch the gearboxes. Motor2 still has problem like before.

Ok, thats good sleuthing. One of the bearings in the motor must have failed.