Hello everyone, the following is the problem I am encountering.
I just uploaded Sweep example to arduino Leonardo and wired everything with external power from a USB 2A charger. SG90 works perfectly, but MG996R doesn't work at all! What I get is very, very, very weak "dot, dot, dot, dot... voice" from MG996R
I really need MG996R for my project. I appreciate for any solution.
USB 2A chargers often have very thin wires and micro USB connectors. It seems like yours can't actually provide enough current to drive the larger servo. Try it with 4 x AA batteries instead.
OTOH you could simply have a bad servo. Do you have any other way to test it?
Steve
Hi,
You have gone to a servo that has a running current of 500 to 900mA.
Stall current of 2.5A
It will draw more as it starts, also you are drawing that current through the Arduino Board, I'm not sure if the PCB tracks are heavy enough for it.
Have you a DMM, check the supply voltage at the servo plug and at the 5V pin of the Arduino.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom.. 
Great I found the problem
Just like Steve said, the external USB power is not enough. I used 5V power from arduino instead and it works!
I will look for proper battery power for it.
Thank you Steve and Tom~~~