KFLOP not talking on USB

[hatcat]

Hi Tom,

My KFLOP will no longer connect to its PC. The PC does not recognise it on power up, or on disconnect & reconnect (no sign on jingle from the PC and neither KMotion or KmotionCNC can connect to it).

The main 5V power supply died quietly for some unknown reason. Now that I have replaced it, the KFLOP seems to power up as previously (short delay and then three green LEDS with a little flashing), but as far as I can tell, the USB data lines have nothing happening. The PC port recognises other USB devices. Perhaps the power supply didn't die quite as quietly as I would have liked!

Do you have any other tests I could do to confirm (or otherwise) that the KFLOP has been damaged?

Assuming the worst, do you have any suggestions as to how to take out some insurance against it happening again? I've thought about a 5V1 Zener across the supply rails but I don't know how effective it would be. I chose this power supply because I'd seen no problems using this brand previously where I work and the build quality seems good.

Thanks for your help and I guess I'll be seeing your shop soon!

Have a great day,
Peter

[TomKerekes]

Hi Peter,

Sorry to hear that. I agree the 5V input voltage probably spiked to damage the FTDI USB interface which is one of the few things that are powered with 5V. I can't think of any other simple tests. That chip has an absolute max rating of 6V. A 5.1V Zener diode might provide some protection.