Help with my Macintosh Classic

[OsvaL]

Hello everyone,

I recapped the logic board and the analog board of my Macintosh Classic but when I turn the computer I hear the chime and then I get a gray screen with a pointer I can move using the mouse. It will no go further than this gray screen.

If I disconnect the hard drive I get the usual floppy with the question mark. I tested the hard drive power cable with a voltmeter and I got a strong 12V and 5V respectively. I guess the hard drive may work but has the boot files corrupted.

Something that caught my attention and I don’t know if it is part of the problem is that there’s no way to make it boot from the ROM using command+option+x+o, I tried doing it with and without the hard drive connected with no luck. I don’t know if the keyboard has a problem also but as I said before the mouse at least works when I move it during the gray screen.

For now I don’t have any floppy disk with an operating system to try, I count on booting from rom but I don’t know why it’s not working.

I also washed the logic board to remove all the electrolytic fluid from the leaked capacitors and then used some Qtips with IPA to clean the stubborn parts.

Thanks for the help.

 

[Alex]

If I disconnect the hard drive I get the usual floppy with the question mark.

It would appear that you isolated far enough to see a question mark so it is promising but testing might prove more difficult without diskettes.

I am no expert re the Classic but I have some questions about the hard disk.

Does it sound normal to you?

Does it appear to make attempts to start up from the HD?

The solid grey screen would tell me (no expert remember) that it might be trying to boot from the HD but gets stuck somewhere and as far as it gets, the flashing disk icon would not apply.

Try any diskette, even if there is no OS on it. It would tell you something about the general health of the machine and whether it is following some logic. For example no OS so eject the floppy.

 

[OsvaL]

Thanks Alex,

The hard drive sounds like it is working, I mean, I can hear it spinning and changing the speed. What I don’t hear is the typical clicking noise of a needle reading the plates inside.

About the floppy drive, I took it apart and cleaned everything, used white lithium grease to lubricate in the parts recommended in a guide. It won’t eject any floppy when it doesn’t find the bootable files. It looks like the motor that ejects the floppy is broken, even though I can hear the drive trying to read the diskette.

Thanks again,

 

[bibilit]

If the gear of the floppy is broken, your best option is to remove the motor altogether. 

Problem is, the upper tray can have troubles falling down, and drive is then unable to read any disk. 

If you have any other Macintosh, try the hard drive, to isolate the problem. 

Try again the Rom boot, only tried it once myself and was a bit tricky to get it going. 

If you have an external SCSI enclosure, had a try. 

 

[OsvaL]

If the gear of the floppy is broken, your best option is to remove the motor altogether. 

I found the problem, one of the gears is broken. I will try to find the blueprints to 3D print it.

 

[OleLila]

May or may not be helpful to your exact problem but pretty good series right now on troubleshooting several Mac classics....go to YouTube and search Adrian’s Digital Basement

 

[OsvaL]

May or may not be helpful to your exact problem but pretty good series right now on troubleshooting several Mac classics....go to YouTube and search Adrian’s Digital Basement

Thanks! I'm following this guy and yesterday he released the part III of this "repairathon" I hope I can learn something from his videos.

 

[Realitystorm]

If you are looking for a gear for you floppy, and it's the one that typically goes....  there is a small gear made of softer plastic that breaks down over time.

The thread I've linked to has suggestions of where you can buy a printed replacement.

https://www.ebay.ca/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR0.TRC0.A0.H0.Xeject+gear.TRS5&_nkw=macintosh+gear&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=floppy+gear

https://www.shapeways.com/product/M84R343FR/4-x-gears-for-macintosh-512k-vintage-floppy-drive (I got mine from here, but that doesn't seem to be for sale anymore)

https://www.shapeways.com/product/27DNUVPJA/replacement-floppy-drive-gear-for-macintosh-comput?optionId=148365838&li=marketplace

 

[OsvaL]

Thanks @Realitystorm I will try to get a replacement. That is the exactly same broken gear, the smallest one that goes to the motor.

 

[rplacd]

For daily use you might just use a FloppyEmu anyway – after all I get most of my software from the web.

 

[blindowl]

Something that caught my attention and I don’t know if it is part of the problem is that there’s no way to make it boot from the ROM using command+option+x+o

Yes, shouldn't the computer boot from ROM, even if floppy and HDD are disconnected? I think so...