Motor did not respond

Hi, I attempted to use codes for motors. Only 1 motor (B) moved while the other motor (A) did not.
I checked the manual, applied a little extra grease to the gearbox of motor A, checked that there were no clearance issues between the Microbot and the wheels, but motor A still did not respond.
What other actions should I take ? e.g. :
(a) disassemble motor A (including removing the motor from the gearbox) and reassemble again ?
(b) disassemble motors A and B, interchange them and reassemble again ? or
(c) something else ?

Try (b), then note if the issue follows the motor or still affects the side it previously affected. This will help identify if it is a motor fault or something else.

I tried a couple of things :
(a) The issue followed the motor when I tried (b). I also tried to run a confirmation test by connecting just the gearbox and the motor to a 1.5V battery (assuming that the voltage would be enough to power the motor ?). The motor did not spin.
(b) Then with the remaining motor (which I interchanged) fixed to the Microbot, I ran a code against it and it spinned.
What should be my next course of action ?

Has the motor which doesn't turn worked in the past ?

You can use a multi-meter to measure the resistance of the motor which doesn't work and compare against the resistance of the motor which does which may determine what the failure mode may be.

This is the first time I am trying out the 2 motors. I got them ~3 months back newly shipped. The motor which doesn't work has a resistance of 8.2Ω and the one that works is 7.4Ω.

Does the motor shaft spin freely by hand [without gear box] ? Sometimes motors will get damaged and armature rubs against magnets.

premelec said:

Does the motor shaft spin freely by hand [without gear box] ? Sometimes motors will get damaged and armature rubs against magnets.

Click to expand...

Do I test the motors with 1.5V battery or I need a higher voltage ? The motors I have are the ones supplied in the bot120 set.

What I suggested is just turn the motor shaft with your fingers - no voltage on it - see if bearings and armature are in mechanical good condition - you reported electrical resistance value indicating brushes are ok...

I tested the motor shaft, and I can spin it. How possible is this a circuitry problem on one side of the bot120 ?

If the motors are fitted to your Bot. Remove them, place them side by side and do some more tests on them.
Treat them as twins, apply the same voltage to each one in turn, noting any differences.( I know one of then is being difficult).
Check the current taken by each one.
Is one getting warm when voltage has been applied, leave it connected for a minute or two.
You will learn a lot from this exercise, all good for the future.
Don't know how to check current? Google is your friend.
Good luck, these things come to try us.
Regards, Bear..

Yes, I am thankful for your advice. I understand your point. This was the reason I asked what test voltage is suitable. Different motors can require different voltages. Is 1.5V ok ?

What is the correct voltage for these motors?
When you purchased them, did it state the voltage?
In your Bot. what voltage are they running on?
What does the manufacturers info. state?

Stick with it!

The bear said:

What is the correct voltage for these motors?
When you purchased them, did it state the voltage?
In your Bot. what voltage are they running on?
What does the manufacturers info. state?

Stick with it!

Click to expand...

No, the voltage was not stated. The only piece of info I had was I can run 3 X 1.5V batteries on a Microbot that powers 2 motors (part of the voltage will be used for other parts of the circuitry).
No manufacturers' info because this is not one of the standalone motors we see in the picaxe store (where some specifications were provided).
So, I 'leaned on the safe side' and used a 1.5V battery to test each of the 2 motors. I had 1 motor working on the Microbot and 1 that doesn't.
When I used a 1.5V battery, detached the motors and connected them independently, none of the motors spinned.
When I connected both motors to the Microbot and ran the downloaded program which was supposed to spin 2 motors, only 1 motor spinned.

Introduce the motors to 4.5 or 5 volts, they need to live in the real world.
Good luck............

pkf said:

Yes, I am thankful for your advice. I understand your point. This was the reason I asked what test voltage is suitable. Different motors can require different voltages. Is 1.5V ok ?

Click to expand...

Looking at the schematic on page 48 of the manual, it seems clear that the motor drivers are running at the battery voltage, 4.5V. Have you tried running the motors at 4.5V?

One thing that can happen with these small motors is that pushing on the shaft can sometimes move it a tiny bit, making it slightly stiff. I notice that the instructions mention that you may need to push on a hard surface to fit the worm gear to the motor.

I'd check both motors at the correct voltage, 4.5V, and also try spinning the defective motor shaft whilst power is applied, as sometimes this can be all that's needed to free things up and get them working properly.

>>>Thanks<<<. I managed to get both motors to spin on the Microbot. Both your inputs were great. I have an additional question, not exactly related to the motors. The Microbot is wheeled along balanced by a skid behind. Is it a good practice to add a small rubber gasket below the skid to maintain it, or will this result in inaccurate sensing of the line tracker because it is no longer parallel to the surface of movement ?

There is a small blue plastic skid in the kit, simply place this over the metal post.

>>>Thanks<<<