68kMLA Classic Interface

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Mac Classic very slow boot process, no ADB/SCSI/Floppy
Posted by: elemenoh on 2020-04-20 18:46:24 After recapping this board, it displayed lots of garbage with a RAM card installed and distorted fat vertical bars when the card was removed. I've been meticulously checking every trace, bodging where needed. At this point it chimes and displays a normal gray screen, but is very slow to progress. It eventually will show a slow flashing '?' despite a good HD/Floppy attached and a bootable floppy in the drive. The cursor does not move. Everything is okay with a known good MLB installed. So I still have some problem on this board, but am not sure where to look at this point. I've marked up a copy of the schematic showing everything tested. A mixed red/green line means there was an open that was repaired. Is there a particular area of the board I should be checking? Is there a likely bad component I should try swapping? View attachment Current_Symptom.mov View attachment Original_Symptom.mov View attachment Macintosh_Classic_Schematic_Audit.pdf
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