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[Macintosh Plus 1MB] Help with booting to system disk for first time. Disk, floppy drive, or ram problem? Video in comment.

vorg

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Aug 30, 2022
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Hi all,
I recently got a Macintosh Plus from someone in my area. I bought it because I have some experience with CRTs and though it would be a cool display to have. After checking the analog board and seeing the caps all looked fine; I realized it just had some cracked solder joints. I reflowed anything with a connector/wiring harness, and that fixed the display. So I got curious and started down the path of repairing the entire thing and buy a boot disk and a keyboard and mouse. I'm still waiting on the keyboard and mouse, but the boot disk came and I needed to take apart and clean the floppy drive to get it to read.

This is a video of that first time I booted it with the floppy inserted:
I cleaned the floppy drive following this guide on youtube:

I used some vinegar on the metal plate part and the top metal part with all the springs. Followed by 97.5% isopropyl, then acetone, then RO water, then isopropyl again. The main assembly of the floppy drive was cleaned liberally with isopropyl. I had no lithium grease; but I did have a silicon lubricant spray. I applied it liberally to the two metal assemblies, and I sprayed it onto a q-tip to apply it to the 4 "pegs" on the main assembly as well as the wormgear.

The assembly seems to work really well outside the Macintosh; almost "throwing" the floppy disk on ejection like the video I followed. But in the Mac, it doesn't consistently read or load; and after that initial video; it gets stuck on the "smiling Mac" icon. The drive makes a horrid noise that, with or without a disk, which I captured here:
But the "Address Error" message seems more like RAM: . Is it both?
 
Why are you messing with the floppy drive for an obvious RAM problem?

You need to clean your RAM. Open it up, take out the SIMMs, burnish the contacts with a pencil eraser, brush off (do not blow on) the eraser dust, reinstall firmly. Someone had a Mac SE thirty years ago that would crash within a minute or two of startup, after I did this it was solid as a rock.
 
Why are you messing with the floppy drive for an obvious RAM problem?

You need to clean your RAM. Open it up, take out the SIMMs, burnish the contacts with a pencil eraser, brush off (do not blow on) the eraser dust, reinstall firmly. Someone had a Mac SE thirty years ago that would crash within a minute or two of startup, after I did this it was solid as a rock.


Please read the post before replying next time.

The floppy drive was unusable, so I cleaned it.

This was the first time I have ever booted the Macintosh with a disk in the drive.
 
That sound from the floppy drive is the eject motor free spinning, which means that one or more gears in the eject mechanism are broken. You'll need to source replacement gears and rebuild the eject mechanism.
 
Clean the RAM, but I'm also wondering if you have a power issue (the flickering / waviness in the first part of the video is suggestive). You can check voltages at the rear floppy port:

Screen Shot 2022-09-29 at 3.57.17 PM.pngScreen Shot 2022-09-29 at 3.57.26 PM.png

Source: Pg 38-39: https://vintageapple.org/macbooks/pdf/Macintosh_Repair_&_Upgrade_Secrets_1990.pdf

If the voltages are off, you'll need to recap the analog board --- those caps are nearly 40 years old (if original) and can be duds now despite appearing fine.
 
The ejection gear on the Apple Floppy Drives fall apart on most old drives but can be replaced (there is a video on YouTube). If you need a replacement I have purchased several off Ebay from a guy that resin prints them. They have worked on all my old Macintosh and Apple 3.5" drives. Search Ebay for "Gear for Macintosh 512k Floppy Drive eject Mac Sony Apple DRIVE MP-F51W MP-F75W"; I think it's about $10.00.
>Charles
 
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