I am out of ideas. I tried already to replace some typical faulty TTL chips on the Disk Controller itself (74LS174, 74LS132, 74LS259) and on the analog board of the drive (74LS125).
The Apple II+ itself is working (showing the prompt, typing in some BASIC statements working, beeps on powerup).
If I insert the Disk Controller card (connected to 1 drive), I can see only the Apple ][ logo, but no prompt. The Disk Drive is continously spinning (and do not stop), and I don't hear any head movements (with and without an inserted disk).
Control Break helps to get the (BASIC) prompt back, but the drive is still spinning and spinning and ...
Any suggestions what to measure or to replace ?
I do not have any spare drive nor any second Disk Controller card (to compare)...
The Apple II+ itself is working (showing the prompt, typing in some BASIC statements working, beeps on powerup).
If I insert the Disk Controller card (connected to 1 drive), I can see only the Apple ][ logo, but no prompt. The Disk Drive is continously spinning (and do not stop), and I don't hear any head movements (with and without an inserted disk).
Control Break helps to get the (BASIC) prompt back, but the drive is still spinning and spinning and ...
Any suggestions what to measure or to replace ?
I do not have any spare drive nor any second Disk Controller card (to compare)...