DeChief
Active member
I picked up a free Mac 512Ke with extended keyboard and mouse 6 months ago and have only just now gotten around to messing with it. When I first got it home, it powered on to a question mark floppy, so naturally I was ecstatic to have just been given a free working Mac and put it on my shelf to be cleaned later.
Fast forward to last week and it was throwing up a sad mac with error 028000, pointing to a faulty RAM chip at G12. So I de-soldered it and installed a socket in its place, and powering it up without the old chip gave me the same error. I ordered 3 new chips and installed one of them today, and it fired up to a question mark floppy symbol again! Before servicing the internal FDD I decided to give my external 800K drive a quick go and it booted first try with a copied System 6 disk I had laying around.
I'm not sure if that was a fluke or what, because it never worked with that floppy ever again, and I was forced to initialise it when I checked the disk in my SE/30. After that, every test I've conducted was with one of the two "512/800K System Tools" floppies the machine came with. 1 of them booted a few times but with a very slimmed down version of the menus (there wasn't even a Shutdown option and I couldn't eject the floppy by dragging it to the trash), and then it eventually stopped working. The other disk has continued to work on and off in the 512Ke despite reading and imaging perfectly in my SE/30 with DiskCopy 4.2. I was able to make a new disk using that image, and it works with the same inconsistency as the original.
In-between all of this, I cleaned and lubricated the internal drive and tested that it worked, and it displayed the exact same symptoms as the external drive... until I put it back into the 512Ke. For whatever reason, the drive only works when it's sitting at this specific angle outside of the machine, and even then it's just as inconsistent as the external:
I tried another yellow stripe floppy cable and it acted the same, so I re-flowed the solder joints of the FDD connector on both the FDD and 512Ke board itself and used some DeOxit D5 - nothing changed. I eventually managed to get it working while properly positioned inside the machine with the floppy cable twisted like this, but it was still inconsistent and was now booting at HALF the speed as when the drive was outside of the machine.
The last thing I tried was putting the internal FDD into the external enclosure, and the external FDD inside the 512Ke, and it gave me the same results as above. I've beep-tested both of my yellow stripe cables with a multimeter and both ends have perfect continuity.
TL;DR summary:
- known-good external and internal floppy drives
- known-good boot floppies
- working inconsistently, partially dependent on drive position
This is driving me absolutely up the wall, what the hell is going on here?!
I reflowed the entire analogue board but all of the capacitors are original, could this possibly be a voltage issue? Usually I replace the capacitors on Mac Plus analogue boards even if they're working fine, just for the sake of longevity, so I will eventually do that for the 512Ke as well - not before further investigating this floppy problem though.
Fast forward to last week and it was throwing up a sad mac with error 028000, pointing to a faulty RAM chip at G12. So I de-soldered it and installed a socket in its place, and powering it up without the old chip gave me the same error. I ordered 3 new chips and installed one of them today, and it fired up to a question mark floppy symbol again! Before servicing the internal FDD I decided to give my external 800K drive a quick go and it booted first try with a copied System 6 disk I had laying around.
I'm not sure if that was a fluke or what, because it never worked with that floppy ever again, and I was forced to initialise it when I checked the disk in my SE/30. After that, every test I've conducted was with one of the two "512/800K System Tools" floppies the machine came with. 1 of them booted a few times but with a very slimmed down version of the menus (there wasn't even a Shutdown option and I couldn't eject the floppy by dragging it to the trash), and then it eventually stopped working. The other disk has continued to work on and off in the 512Ke despite reading and imaging perfectly in my SE/30 with DiskCopy 4.2. I was able to make a new disk using that image, and it works with the same inconsistency as the original.
In-between all of this, I cleaned and lubricated the internal drive and tested that it worked, and it displayed the exact same symptoms as the external drive... until I put it back into the 512Ke. For whatever reason, the drive only works when it's sitting at this specific angle outside of the machine, and even then it's just as inconsistent as the external:
I tried another yellow stripe floppy cable and it acted the same, so I re-flowed the solder joints of the FDD connector on both the FDD and 512Ke board itself and used some DeOxit D5 - nothing changed. I eventually managed to get it working while properly positioned inside the machine with the floppy cable twisted like this, but it was still inconsistent and was now booting at HALF the speed as when the drive was outside of the machine.
The last thing I tried was putting the internal FDD into the external enclosure, and the external FDD inside the 512Ke, and it gave me the same results as above. I've beep-tested both of my yellow stripe cables with a multimeter and both ends have perfect continuity.
TL;DR summary:
- known-good external and internal floppy drives
- known-good boot floppies
- working inconsistently, partially dependent on drive position
This is driving me absolutely up the wall, what the hell is going on here?!
I reflowed the entire analogue board but all of the capacitors are original, could this possibly be a voltage issue? Usually I replace the capacitors on Mac Plus analogue boards even if they're working fine, just for the sake of longevity, so I will eventually do that for the 512Ke as well - not before further investigating this floppy problem though.
Last edited by a moderator: