hi,
Is it normal that the vex microcontroller makes such noise? when i plug the vexnet keys off, the beeps stops but as soon as i plug in back, same noise comes.It stops sometimes but mostly i have to hear this annoying sound. Hel will be appreciated 
You are probably hearing the motors, they beep like that all the time when they are sent power and its only noticible when they are given a power too low to move
if you want it to stop implement a joystick deadzone in your program
I hear that noise as soon as i plug the vexnet keys. I mean if i switch joystick off, the beep goes. but as soon as i turn it on, beep statrs.
Do you have anything in any of the ports?
Second what is the beeping sound like?
Third can you get us a video or picture? (preferably video)
Also does it happen when you hardwire?
So what I hear is some hum in the background. I hear you / see you move the robot backwards and forwards and then I hear a hum in the background?
If you are talking about the noise when the robot moves, that’s the standard gear noise you get from the motors
If you are talking about the hum, it’s from the servo that you have installed on the claw, it’s just at it’s zero point. Does it go away when the Cortex “brain” is powered off?"
If thats not the noise you are talking about then I can’t here it. You said a beep, so I’m listening for a beep like from a PC when you turn it on .
The video was a good idea!
I hear a low-level squeal that sounds like a motor getting just enough power to make an annoying sound, the sort of thing that happens with a joystick that isn’t perfectly set on zero, which is a common thing to happen if you don’t have your code written to provide a dead band (dead band example: if that joystick channel does not read above 10 or below -10, then the power to the motor stays set at zero).
Also, can you try temporarily disconnecting the two-wire leads that go to your claw motor and your arm motor and see if the noise stops? If not, then it’s probably your chassis motors squealing from a lack of dead band.
Agree with this. Try disconnecting the motor. I haven’t heard anything about a cortex making noise.
Some common sense about motor power curve:
A 393 motor under no load will not move at all given a power less than 8 or so. If under load, this value can increase to around 20-30 for a base, or even higher for high torque application.
https://vexforum.com/attachment.php?attachmentid=6475
Alright so the noise stops when i disconnect the left motor from its slot 1 connected to the cortex. Still cant troubleshoot though. Is there any problem in slot one? It does not make noise when i connect it to slot 10.
its all part of your program, there is no difference between ports
your program is sending power to those ports which is causing the noise, we cant tell why they are being powered without your code
I know the problem the joysticks throttle buttons are being pushed a little bit which is seting the motors to one. This is completely normal and is nothing to worry about. I hopes this helps.
If you want to fix the this you can use dead zones.
Ok so it was the classroom kit that came with clawbot. the default code of clawbot wass already there on the cortex.
Really appreciate for all the helping replies. I am sure ill troubleshoot sooner. Its all fun
Ah another issue. Can anyone tell why my all points on the cortex suddenly have turned to red?
Points do you mean LEDs or Ports?
Sorry for being vague. I mean the three leds on cortex i-e robot, vexnet, game
And can you tell me where to learn about this ve joystick dead zone. Have never heard about it.
Ok so what you want to do is turn of cortex and controller unplug battery and then plug it back in and turn it back on. If that doesn’t work you will need to download new firmware.
For the red lights, your robot battery might just be dead. Charge, try again, and let us know if there is still an issue. Also, take a look at this troubleshooting guide, it is generally helpful for all sorts of issues:
Regarding the humming noise, this is coming from the motors, not the cortex, and it is perfectly normal and okay. What is happening is that the motor is receiving a tiny bit of power, not enough to make it move, but enough to make a sound.
This is happening because the joystick usually never goes back perfectly to the exact middle where a value of zero would be; it has a value of 1 or 2 or so. This means that the motor is getting a very small amount of power making it hum. When you plugged the motor into port 10 it stopped humming because the robot is programming to power the motor in port 1, not in port 10.
To prevent this people have mentioned a deadzone on the joystick, essentially this is saying that if the joystick is almost at the middle, treat it like it is at the middle. So if the joystick value is less than, for example, 10, it ignores the actual value and just uses 0.
To set up a deadzone you will need to write or use an example program, do you have RobotC or EasyC? To be honest, if it is only the humming that bothers you, I wouldn’t be too worried, because it is perfectly normal any robot does it.
Thanks alot kevin for the awesome explanation. Now i got almost everything. Everyone was trying to explain the same words but i was just not picking up. Just a small question, why the motor makes noise even when i drive the bot? i mean now the motor is getting all the power i am giving through joystic. Thanks all again