Hi all - new on here and with a problem (of course).

Machine is a Wabeco 1210E CC with legacy Winpc (WINDREH) CAD/CAM and Wabeco controller. Bought new many years ago and updated Windows software to R19b complete with dongle. Support from Pro Tools has been excellent, but it's Saturday and I could do with some advice.

System was fine until a recent pc crash caused me to reinstall software on an old laptop which still sported a built in 9 pin male serial port. This also worked fine. Not content (stupidly) to rely on another old pc I bought a USB/RS232 com port replicator cable to try on a current laptop.

Reinstalled software and dongle response was fine. Everything checked out on the Winpc set up pages but no controller response. Went back to the old laptop and connected direct to the serial port again. Now no controller response on this setup.

Discovered a blown 2A slow blow fuse on the controller board. Disconnected the controller from pc and replaced the fuse but it glows orange and blows each time AC power is switched back on.

There's also a nice (capacitive?) discharge across the fuse contacts as you insert the new fuse but this may be normal - I'm an engineer!

Is it possible that the USB/RS232 CPR has caused a mischief with the dongle or controller or both? I note from the CPR data sheet that pin 9 on the D connector can be used to provide USB 5V for unpowered downstream users. The dongle has its own 12V power supply.

Any advice appreciated but please keep it simplistic in electronic terms.