Servo Robot arm

I am building a robot arm using the https://howtomechatronics.com/tutorials/arduino/diy-arduino-robot-arm-with-smartphone-control/ tutorial, but when moving any slider, all of the servos just make little movements,(they kinda vibrate). After a while the app displays error code 516 when moving the sliders.(MIT app inventor) . I also used the exact code from the site. What is going wrong?

svenyvar:
What is going wrong?

You’re not providing enough detail.
Maybe it’s a power supply issue.

I am using an external 5 v power supply, the circuit and details, as well as the code are displayed on https://howtomechatronics.com/tutorials/arduino/diy-arduino-robot-arm-with-smartphone-control/ I checked, and all servos and the hc05 are getting around 5v.

You’re not providing enough detail.
Maybe it’s a power supply issue.

TheMemberFormerlyKnownAsAWOL:
You're not providing enough detail.
Maybe it's a power supply issue.

What details do you want? Because a lot of details can be found on https://howtomechatronics.com/tutorials/arduino/diy-arduino-robot-arm-with-smartphone-control/

What is

an external 5 v power supply

?

I am using this circuit
This is what I mean by an external power supply.

Are you using EXACTLY the same servos, SG90s and MG996Rs? Do you have them hardwired, not using a breadboard or anything similar?

What is the CURRENT rating of your "external 5V power supply"? Maybe it's a power supply issue.

Steve

What is connected to the red arrow labelled “5V external power supply”?

slipstick:
Are you using EXACTLY the same servos, SG90s and MG996Rs? Do you have them hardwired, not using a breadboard or anything similar?

What is the CURRENT rating of your "external 5V power supply"? Maybe it's a power supply issue.

Steve

The servos are from AliExpress, so I can't be sure if they're exactly the same.
I do have them hardwired.
The current rating of my power supply is 4.89 volts.

The current rating of my power supply is 4.89 volts.

Try again

Now it's 4.9V, and it stays like that.

TheMemberFormerlyKnownAsAWOL:
What is connected to the red arrow labelled "5V external power supply"?

A 5V 2A smartphone samsung power brick

Ok, that’s good for maybe two servos.

svenyvar:
Now it’s 4.9V, and it stays like that.

Current != Voltage

TheMemberFormerlyKnownAsAWOL:
Ok, that's good for maybe two servos.

How many volts do you suggest I use? And why would that website say otherwise??

Five volts, six amps (one per servo)

Ok I will try that then. Btw sorry for my bad English

I've tried using 3 amps, and nothing changed. When I try to move one particular servo in the app, all of them start to make little movements, isnt this a code mistake ?

svenyvar:
I’ve tried using 3 amps, and nothing changed. When I try to move one particular servo in the app, all of them start to make little movements, isnt this a code mistake ?

I don’t know.
Could be a code mistake (I can’t see your code), could be a wiring mistake (I can’t see your wiring).
Did you remember to connect all the grounds?