Serious problems

I have serious problems with Pololu servo-controllers. Within a few days the third(!) servo-controller went broken. I have written a Java program to communicate with the controller (RS 232). Everything works fine, but after one or two days the servos do not turn anymore. The green LED always flickers when I send dome data, but the servos do not turn and they do not hold the position (I can turn them by hand). The power supply for the controller is 9V and the servo supply is 4,5V. How much current can one servo-pin on the controller pull? I tried the pololu transmitter as well. It works fine but after failing with the java program the pololu transmitter does not work either.
Three broken controllers in one week- That`s too much…
Can anyone give me some advice?

Greetings

Wolfgang

Hello.

Are you sure the servos are working? The controller can deliver plenty of current for typical use (by the way, we don’t say that the servo controller is “pulling” the current when it is supplying it to the servo). You can easily check if the traces are blown by doing a continuity check between the appropriate power pins (the middle and outer pins on the servo ports should be tied to the corresponding pins on the servo power connection).

I suspect you might have just inadvertently changed the servo numbers to which the servo controller replies. Can you try resetting the servo IDs to the numbers you’re trying to control?

- Jan

Dear Jan,
thanks for your fast reply! I tried all pins and the servos still do not work. When I use a new controller, the servos work. Instead of batteries I use two power supply units. Maybe this is the problem (it could be that the power supply units make some short peaks which destroy the CMOS microcontroller on the board).

Greetings

Wolfgang

From what you’ve posted, it sounds like the servo controller is fine and that it is set to respond to different servos than you think. Here’s an easy test: in Mini SSC II mode, do the servos hold their positions after you send the first byte?

- Jan