How to determine if the ST works if I have no monitor - Gunstick/SThints GitHub Wiki

Switch on, the power LED should be on. If not: power supply is dead or badly connected.

The floppy light should come on quite soon after boot. If you have no diskette, then it takes around 40 seconds until the light goes off. When the LED is off, the ST has reached the GEM desktop.

Any time after reset: press a key. You should hear the classic ST key click if you connected to an amplifier.

If it is a PAL (50Hz) model, connect to stereo: Switch the ST on. You should hear a faint 60Hz humm shortly followed by a 50Hz. Holding the reset button in: 60Hz. Releasing: 50Hz. => The OS boots and the video chip works.

Does the floppy work (new floppies are very silent)? Insert a disk. Remove the disk. Check where the hole in the round metal part is located. Insert disk again. Remove again. If the location has rotated, then the floppy motor works.