8 Servo Controller

I did as the instuctions say and applied a 9 volt battery to the connection labeled con 2. Making sure the correct polarity is being applied to the positive and negative terminals.

Upon initial Startup the red and yellow LED started up, then after a bit the red went out and only the yellow continued to be lit.

I tried as the trouble shooting section suggested and removed the CHIP then applied power and grounded out the green LED and nada. Same thing with the red. The yellow lights up as normal though when it’s pin is grounded.

Any suggestions?

Doh Wrong forum

Nix this for now. Got some sucess with this recently. I still have yet to see the Green light ever turn on. But I did get the controller to issue commands.

What type of power supply do you recommend? With this 9 volt battery after about 10 minutes of use it is very HOT.


The battery should not be getting hot at all since the board only draws about 10 mA. Are there any parts on the board that are getting hot? You should also check all of your soldering to make sure that you don’t have any shorts across leads. Also, double-check all of the components to make sure they are in the right locations and in the correct orientations. In general, a 9V battery is reasonable power source for the servo controller logic supply.

If the green LED does not turn on, you most likely put it in backwards. You could also check resistor R6 for bad solder joints. If you have some other LEDs hanging around, you could try temporarily soldering them across the green LED (in the right orientation) and see if you can get it to light up through the IC. The green should flicker with every serial command.

- Jan

Actually I bought it from you preassembled…


We fully test all assembled units prior to shipping, so your servo controller worked at one point. Was there any indication of rough handling when you received the package?

At this point, is everything other than the green LED working? Do you have a meter that would let you measure voltage on the microcontroller (pin eight) and the current drawn by the servo controller. What is the current consumption with the microcontroller plugged in and without it plugged in?

As you work with the servo controller, please be careful about static electricity. Also, make sure that the servo controller is not sitting on a conductive surface (such as a metal table or anti-static bag).

- Jan