New T3.6 USB serial port problem

I have just bought a new Teensy 3.6. I soldered pins to it. I plugged this into my Win7 desktop. The OS recognised a new device. It claimed to have installed a driver and BLINKY began to flash the on-board LED. OK so far.

I then attempted to find the board with Arduino 1.8.4 and Teensyduino 1.39. I changed the "board" to "Teensy 3.6" and searched for the "port" - but I could not find it in the list.

I closed Arduino IDE and looked under "Control Panel"/"Device Manager" to see if there was a new COM under "PORTS (COM & LPT)" - but it was not there.

If I unplugged the USB 2.0 cable connected to the board, I heard the the familiar "Hi-Lo" sound from the speakers, indicating a USB device removal. If I plugged the USB 2.0 cable into the desktop socket again, I got the familiar "Lo-Hi" sound to indicate a new USB device attached.

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I connected a (previously used) Teensy 3.1 board via the same cable, and this was recognised OK both within "Arduino" and "Device Manager". I tried an older Teensy 3.6 with the same cable - and this one worked OK under "Device Manager" (as COM10).

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I then tried connecting the Teensy 3.6 to another (different) Win7 desktop. Same thing happens. After driver install, the Teensy 3.6 gives the "Lo-Hi" sound when plugged in (USB connected), but fails to show in either "Device Manager" or "Arduino IDE". But another (different) Teensy 3.1 works OK. on this alternative desktop.

Any suggestions? (The Teensy's that do work OK were installed under a previous version of Arduino IDE and Teensyduino).

As shipped the Blinky has No Serial support. New out of box requires a button push for first recognition and programming.

There's a page about that on PJRC.com - but it is confusing with T_2 and T_3 and I can never find it when needed - pretty sure it is not www.pjrc.com/teensy as printed on the card though.

(Thanks defragster - our posts have co-incided).

Doh... I think I have solved the issue.

When a new Teensy device arrives, it is pre-programmed with BLINKY - but the USB is configured as "RawHID" and not "serial". By setting the "USB Type" to serial and then programming via the boatloader, the Teensy device will then become a "serial" device - and it will THEN appear under "Device Manager" as a COM port.

Funny how I have used three Teensy boards previously but never realised this is what happens !!