Roger

Hi Sorry, by brownout I meant a momentary dip in voltage at a critical place in the circuit that caused either a watchdog to fire or the ordinarily reliable performance of the controller to go haywire. Voltage may only go down below the critical level for a microsecond to induce this depending on the circuit sensitivity. Whether the system recovers on its own is important, and often dependent on so many things! I have had circuits that lock up with such a voltage drop, requiring a full power down to come back to life. I've also had them where recovery is dependent on pulling out the USB lead and putting it back in again (and of course others where recovery happens by itself). EMC susceptibility tests usually pick these issues up, and in most cases, very local decoupling around the USB controller circuitry at design time eliminates the issue before customer release. Of course, I may be barking completely up the wrong tree, but it truly does sound like the USB drop-outs are coincidental with high transient current demands elsewhere, and that, whilst balancing the mount may stop the problem on all occasions, power or ground routing may be the root cause (and that the problem may come back to bite as mounts bed in and friction changes over time).

Duplicate post deleted - sorry software glitch on my PC

Hi folks. First post - and considering a purchase. Reading between the lines this would appear to be a brownout of supply voltage on low level control electronics (the USB controller) as a result of transient high current in the torque motor. A strategic L/C filter somewhere should abate this I'd have thought (and if the pcb is such that additional L is not possible, perhaps just boosting a decoupling capacitor is the quick solution?