strange behavior with motor on about greaseweazle HOT 1 CLOSED

So, apparently, your drive seems to have Shuggart unit 2. In my experience, it can be:

• Because you are actually using a Shuggart drive with ID 2 on a flat cable. There are some plastic jumpers at the rear of your drive to change the ID number. If you want to use this drive as drive a or b, put the plastic jumper on position "1" and use a ribbon cable with a twist.

• If you are sure your are using an IBM PC drive with a not modifiable ID 1, then what you experience may happen because of the cable. For instance, what you experience would happen with a twisted Amiga 2000, Amiga 3000 or Amiga 4000 cable and an IBM drive installed on the edge: the twist is not the same as the twist on a PC cable. But it "half" works because Motor ON signal selects your drive, or SELECT DRIVE A turns on your drive's motor, but not both at the same time. Here, you would have to change the cable.

• It can also happen because there is not enough power supplied to your drive. Try to change the power source: use a real Power supply (double check if your drive needs 12V also), disconnect all other devices if your use an USB hub, connect your Greaseweazle board into another USB connector on your computer if you use it to supply power to your drive.

from greaseweazle.