New to forum and servos....

very inexperienced here. I have the hitec hsr-2645cr servo...

using a Sparkfun board to send commands for left, right, stop and works fine for hitec 1425cr.

but when i plug in the 2645cr all i get is a slow rotation and no response to my commands (left, right, stop pulses)

6 volt supply and it only rotates slowly and will not respond to left, right, stop
pulses.

sent it back to manufacture they said all is fine...

it is digital... do these servos need to be programmed first?

and if so, is their a special interface to write /upload my program?

Any assistance, guidance would be appreciated.