Mac Classic No Drive Troubleshooting

ArtisticLeo

New Tinkerer
Nov 3, 2021
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0
1
Hello all, quick thank you to this community and the talented YouTubers I've followed for years now. It's been encouraging seeing such capable and approachable demonstrations on preserving this hardware history that I largely missed out on growing up, and behold, now have the chance to carry on with.

On the Table for me is a Macintosh Classic that was at one time last known working, but upon delivery presented with a sad mac Error 0000-000F 00000002/3 or equivalent errors. Since doing an analog power recap, and SMD Capacitor recap, deep clean, and reflow, I've been able to get it to reliably come to the boot screen and even access the ROM system. (So fast! So cool!)

I cannot, however, get it to recognize either the SCSI drive nor the floppy drive, even when swapped with known working parts from my SE Superdrive.

SCSI HDD spins up, head actuates within, but seems to stutter or dip in speed. System posts with disk icon

Floppy drive appears to actuate, spins up somewhat feebly, but never seeks or attempts to read any floppy disk I present it.

Voltages appear solid and steady : 4.89v and 12.10 +/- with load attached.


I have the means to replace the rest of the caps on the logic board, but no outward signs of damage to it or the logic board give me any solid leads as to where the disconnect may be. Unit only had typical oily cap surfaces with no major signs of corrosion aside from where the power supply caps on the analog board dripped onto the metal frame itself.

Any suggestions as to where I should prioritize troubleshooting?

Image 1 current state: all peripherals out on desk to access easier
Image 2 Analog board post recap
Image 3 worst extent of damages after removal of corroded SMD caps, prior to deep clean, reflow, and bodge. No evidence of any corrosive damage to any traces or chip legs that I can find.
 

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Garrett

Tinkerer
Oct 31, 2021
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MN, USA
If the hard drive is known good and has been tested in your working SE, I would think it's still a power issue (especially if you hear the drive losing speed). Your SCSI chip could be defective as well, but I don't know how likely that is. Do you have any external SCSI drives you could test the machine with? Even a BlueSCSI DB25 version would work here. If you can boot from that, I'd say it's still a power stability issue. Good luck!
 
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ArtisticLeo

New Tinkerer
Nov 3, 2021
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If the hard drive is known good and has been tested in your working SE, I would think it's still a power issue (especially if you hear the drive losing speed). Your SCSI chip could be defective as well, but I don't know how likely that is. Do you have any external SCSI drives you could test the machine with? Even a BlueSCSI DB25 version would work here. If you can boot from that, I'd say it's still a power stability issue. Good luck!

thanks for your reply!

Further testing the Classics drive in the SE might be something to do in the interim, I haven’t gotten it to boot on that machine that I can recall, however the good working drive from the SE won’t boot on this board either. Any drive never seems to go into seek mode beyond its initial head test that I can tell.

I do not yet have a BlueSCSI, but I did just try the FloppyEMU, it never appears to register with the board either, however, remaining idle on an image that boots fine on the SE

looking more like a logic board issue at this point, both the SWIM chip and the SCSI chip never appearing to send the command down the line to load rhebdrives
 

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ArtisticLeo

New Tinkerer
Nov 3, 2021
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All voltages across the analog board and mainboard were solid. Then Perma-checkers. I'm at the furthest extent of my skills and tools, here.
 

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