Let's Make Robots!

Servo killer

Ok, servo board works perfectly for my quadbot. However, I kill 3 servos(HS-485HB) in a day!!!

This servo board support 14 servos and I have connect them with external power - 7.4v lipo 2800mAh. The battery connected like this(the battery is 7.4 not 11.1v any more):

Here is what happening; When I do the coding I have USB connected and power off from battery. After coding I turn on the switch so servos has enough power to do the moves and USB still connected. It was fine for several attempts but after 5~6 times repeating the same procedure then I got my first servo not working, I replace it and I switched off the battery and did uploading and switch on, then I got 2nd servos burned right the way! No sparks or smoke but bad smells. Same procedure and 3rd servo burned. I have no idea why the servo burned so easily. Anyone have any ideas? I am assuming I probably can't have USB and battery on at same time, especially when the moment I repeating turn on the switch and have high current flows in that impact the servos??

Again, I have to say sorry for my bad English and writing skill. If this is not clearly explain what happened please let me know and I will try my best to explain again.

Thanks in advance for anyone could help me with this issue~~

P.S. Servo shield I am using now:



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I can't tell from the picture where you are attaching the output of VR to the board, but, I think you want to go into the screw mounts titled "servo power". (you probably are doing that, I just can't see it). Diodes are usually used to prevent current from flowing backward, ensuring the current only flows one way. They look like resistors, but usually one color, like black, with 1 stripe. This stripe is the output end. Usually they allow high voltage to pass thru. Like an LED, they consume some voltage in the process. So you wire a few of them in series to get the desired drop. I think the amount of drop depends on the voltage passing thru it. For instance, if the diode is a 50v diode, I think it will drop 1.6v if your circuit uses 50v. If your circuit is less than 50v, the drop will be less. Different diodes have different ratings. It's another way of doing voltage regulation with less limitation on current. Goto radioshack.com and type in diodes and read about the different models.

Yep~ I think I am going to remove that regulator and have 2 diodes to reduce the voltage. To be honest why I am so confused to use 7.4 without reduce because my other Hexapod uses same battery without reduce power but still running with no servo destroyed. Perhaps the SSC32 board done some tricks? But from now on I will have this in mind to reduce the voltage for good.