I have a micro serial servo controller that has stopped working. I have previously used it to control a servo motor with no trouble, but now when I turn it on all 3 LED’s light up. Even after connecting the serial comms and trying to talk to it, the 3 LED’s remain lit. Previously, only the yellow LED would be lit when the comms was connected. I’ve confirmed that the serial cable is working properly, is it possible that the board has somehow been damaged? Is there anything obvious I’m missing here?
Thanks for your help,
All 3 LEDs on upon power-up means that the serial input (the logic-level one) is low. So I’d look for a short from that to ground, or from the RS-232 input to power (since that gets inverted before connecting to the logic-level input). You can also measure the voltage on the serial input pin; if it’s high but the controller continues the same behavior, the pin probably got blown (e.g. by connecting RS-232 voltage levels directly to the logic-level input).
I can’t see any shorting between the logic-level serial input to ground, or from RS-232 input to power. The logic-level serial input is at 5V, whereas the RS-232 input is at 0. All other pins are at 0 except the reset pin and one of the pins for the protocol selection jumper. Is this what you’d expect to see?
That generally sounds right. If the logic-level input is high but the controller powers up with all LEDs on, it’s not a good sign, especially if things used to work and now don’t. Any idea what might have caused it?