Mac stopped seeing FTDI chip

I have been using FT232RL board to take to my project. It was all working fine, until for some reason the Arduino IDE stopped listing the board as a device. I assumed I had killed the chip somehow and bought three more FT232RL based boards, but the Arduino IDE does not recognise any of them.

What should I try next? thanks karl

Have you tried re-installing the FTDI driver?

Yes, but to no avail. I am taking the opportunity to upgrade to El Captain, to see if that changes anything. Thanks

I don't know about Macs, but for Windows this is a known problem if the FTDI chips are copies: http://www.techrepublic.com/article/ftdi-abuses-windows-update-pushing-driver-that-breaks-counterfeit-chips/

Yes, I had wondered about that. The three replacements are cheap and fro China, but I have never seen this problem discussed with regard to a Mac. Is there an alternative to the FTDI chip?

I have been using FT232 FTDI modules with Win7 Pro from Mouser.com
http://www.mouser.com/ProductDetail/MikroElektronika/MIKROE-483/?qs=sGAEpiMZZMuNcqZxhMNT3znYT0k8AsjH
and www.Tinyosshop.com with mini-usb and micro-usb connectors. No issues with either. Got to have a reputable source.