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Apple /// Help

Posted by: Ajaxermd on 2025-08-12 12:05:32

Have an original Apple III, looks like nobody has been inside since the 1980s. I've cleaned and lightly lubed the 3 Apple III drives (internal and two externals), retrobrighted the Apple III and Monitor III and reseated the chips. I just swapped out the Rifa caps on the PSU and the PSU is working.

RAM Diagnostic comes up clean. (Picture)
The internal drive attempts to boot, but won't read any disks. A number of bootable disks came with the machine and none seem to be readable. I guess they could ALL be bad, but unlikely as they were in sealed containers.

Could use advice on next steps. I was considering....
Swapping in one of the other drives into the internal drive or just swapping cables.
Is there a keyboard combo that allows me to boot from the external drive?
Floppy Emu, I have one for the Apple II, but I'd need to modify it to work with the III
I'd try ADTPro, but don't have a disk.

Attached some photos, the machine looks great after the retrobright, and a video showing the failing boot sequence. Many thanks for any help.

Posted by: finkmac on 2025-08-12 12:24:31

you can build an adapter to use the floppy emu, no need to modify it.

i'd use that for testing first... it takes the unreliable floppies out of the equation

Posted by: bibilit on 2025-08-12 21:40:45

Yes, I will swap external to internal for a test.

If your internal is not reading, you can try troubleshooting it. Maybe the speed is bad (299 rpm) or head is bad or dirty.

The drives are Apple IIs with a different board so fairly easy to find.

Posted by: bibilit on 2025-08-13 02:21:22

The drives are pretty easy to work on, first step is to be sure they are running at the right speed, you can use any App on Iphone or probably Android to do so :

‎Strobe tachometer (RPM meter)

‎STROBE TACHOMETER When the flicker frequency of light coincides with the speed of any object, such as a fan, the rotating fan may appear to be stationary. Changing the frequency of the flicker of light may help detect the rotation speed. You may easily use the flicker frequency control buttons...

apps.apple.com

After that, some chips can be faulty on the board, but are still available today (thinking about the 74LS125, that can be fried when the cable is fitted the wrong way) if you swap the external drive, and get it working, you can swap chips to troubleshoot the internal.

Posted by: Ajaxermd on 2025-08-13 08:11:02

Yes, I will swap external to internal for a test.

If your internal is not reading, you can try troubleshooting it. Maybe the speed is bad (299 rpm) or head is bad or dirty.

The drives are Apple IIs with a different board so fairly easy to find.

Ah interesting, I have a couple extra Disk ][s. Can I literally swap the board and the drive mechanism is the same?

Posted by: Ajaxermd on 2025-08-13 09:30:19

OK, attached the external drive to the motherboard and it's fully working. All keys are working and I ran QuickFile Apple Writer /// and Apple // utilities.
Still interested in getting the internal drive working. I already cleaned the head and lubed the rails. The disks are spinning. I'll try the Strobe Tachometer suggested above.

Posted by: bibilit on 2025-08-13 10:03:13

Yes drive mecanism is the same (or really close, but i have worked only a couple of time in an Apple III, but sure i had and issue with a drive and used a Disk II mecanism)
IIRC the board should be close enough for chip swapping.
Here below is a picture of a III drive, the black and white pattern is used to get the right speed set.