1. Why the wheels shake when running after being tightened?

This may be caused by the gap in the motor shafts. The shaking may be more obvious when extended shafts are used.

Since the four Mecanum wheels have to be in full contact with the ground when they move, you need to keep a certain movement space for the wheels in the vertical direction.

2. Why do I need to put nylon washers when installing electronic modules? 

If the metal parts of an electronic module are in direct contact with the metal shell of mBot Mega, a short circuit may be caused and the electronic module may be damaged.

3. Why deviation occurs when mBot Mega moves in a straight line?

The possible causes are described as follows:

• The TT motors are common DC motors without encoder sensors. The four motors are not consistent with each other and therefore run at different speeds.
• The ground is rough and therefore the areas of the four wheels that come in contact with the ground are different, thus the friction between the wheels and the ground is different and a deviation is caused.

4. Why there is noise when mBot Mega is moving?

There are 9 rollers on each Mecanum wheel. When moving at high speed, each roller makes noise when it comes in contact with the ground.

5. Why the default functions cannot be used (such as gesture recognition) after starting mBot Mega?

You need to update the firmware to the factory version before you use mBot Mega. For details about firmware update, see Updating the Firmware of mBot Mega.

6. Why does the previous program disappear after I update the firmware?

mBot Mega can store only one program. Updating the firmware also restores the ex-factory program and therefore the previous program is overwritten. 

7. Why the line following and obstacle avoidance functions in the Makeblock app don't work?

The line following and obstacle avoidance modes in this app are essentially the same as the factory preset programs, so the product also needs to be restored to the factory firmware before running.

8. Can i upload programs with the Bluetooth dongle?

No, the Megapi mainboard doesn't support firmware update, program upload and online debugging through Bluetooth dongle.

9. The LED indicator of a sensor is on after mBot Mega is powered on, but the motor can't rotate, why?

• You need to make sure the motors are properly connected to the motor drivers.
• The battery power is low. You can use brand new Nanfu AA batteries or Makeblock rechargeable battery pack to test again.
• The motor power value set during programming is too low. It is recommended to set a power value of more than 40%.

10. Why the RGB LED module doesn't lit up after turning on mBot Mega?

No power indicator is provided for the RGB LED module. If you want to see a power indication, you can write a program to light up the LEDs when it is powered on.

11. The sensors or RGB LED modules do not work properly, why?

The order of the pins may be wrong. Make sure that the 3 pins (GND, VCC, IN) of the module correspond to the PIN pins (GND, 5V, SIG) on MegaPi, respectively.
Another possible cause is that the electronic module is damaged.

12. What is the main function of the impact switch?

• It can be used to switch between three different factory preset functions of Mega by long pressing.
• In addition, when uploading one program to the product, you can press any of the impact switches to start running it.

13. The impact switch doesn't work, why?

The possible causes are described as follows:

• The force for pressing the impact switch is not large enough. 
• The pins of the 3-pin cable are not connected in the expected sequence.

14. How can I use other Makeblock electronic modules? 

You can connect mBot Mega to the RJ25 series electronic modules through a MegaPi RJ25 adapter. Note that mBot Mega is not compatible with mBuild and Neuron electronic modules.

15. Which electronic modules are compatible with mBot Mega? 

mBot Mega is compatible with most of 3-pin connectors, sensors that can work at 3.3V-5V, RGB LEDs and servos. 

16. Why the mBot Mega will be recognized as "Ultimate 2.0" by Makeblock app？

Some products may encounter this problem due to the old firmware version.

In this case, you may need to use mBlock5 software, select device "mBot Mega" and update the "Online Firmware" to realize correct app control.
If you want to use the origin functions of mBot mega(Line following/avoid obstacles), you may need to update the "Factory Firmware".

You can refer to here for detail information.

17. What should I do if the motor starts running automatically after the mBot Mega is turned on?

It may be that a program has been uploaded to the machine before, which contains instructions for running the motor after powering on. You can refer to this article to update to the online firmware first.