68kMLA Classic Interface

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Apple Disk II repairs

Posted by: bibilit on 2019-01-17 03:03:17 Except for cleaning the head and rails, those are pretty reliable. I have a pair not working properly, one was not spinning at the right speed, but managed to correct to the 300 rpm one, but still not reading. Another is detected too fast and trying to slow down doesn't work. Any advise ?

Posted by: DistantStar001 on 2019-01-17 21:10:48 Try swapping the analog cards to see if you can recreate the malfunctions on the opposite drive.  If so, then the problem is likely one or more of the ICs on the card, if the malfunctions persist regardless of the card, then it's a mechanical issue with the drive.  Also, if you can reproduce the issues with this method, and you have another working drive, try the same procedure with it, and also try swapping the ICs on the card to isolate the defective component.

Posted by: bibilit on 2019-01-17 23:46:14 Thanks, Already swapped analog boards, and those are ok. More a problem on the motor PCB or read/write head.

Posted by: bibilit on 2019-01-26 14:03:21 problem was speed after all, managed to get the two drives working fine. Using a digital stroboscope, i managed to get the fine tuning required. The software procedure (using MECC inspector or Locksmith) didn't worked for me (probably because a scratch disk is used to write and read back some information) Setting the speed just below the 300 Rpm mark did the trick.

Posted by: lowlytech on 2019-02-10 06:54:35 Glad you got the drives working.  Only thing I can say in relation is my amiga 1200 had similar issues with the speed of rotation where it wouldn't read disks at all until replacing a small little capacitor that had gone out of value.  It luckily was a common fault and well documented on the internet.

Posted by: bibilit on 2019-02-10 09:43:25 For those interested, found an Iphone application working just as easily: https://itunes.apple.com/us/app/strobe-tachometer-rpm-meter/id831460940?mt=8 Tested this morning, not as bulky as my last device.

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