So, when I saw an add on Facebook marketplace for a Macintosh Classic and Classic II, I couldn't resist making an offer. I probably paid too much knowing that one computer was working and the other was not, but I'm always in this tension of not wanting to insult sellers with low offers and wanting to keep my retro computer spend to a manageable hobby level and not a lifestyle.
Machine #1, Macintosh Classic
Upon inspection, the Macintosh Classic was booting and running off the hard drive. I don't want to get my hopes up about this, since all of my vintage macs have had failed hard drives, but this one is a Connor and I haven't had one of this brand. Maybe it will survive long after all the Quantum Fireball drives have died?
Other than that, the Classic isn't too remarkable on the outside, one of the ideas I got from Adrian was using an external drives to test all the ports, I was able to confirm all the ports are working (Floppy, SCSI) except the Serial ports, since I don't have a Printer or Modem to use for test. On the inside, I'm happy to report that although the clock battery had not been changed and still have the 1991 date code, it had not leaked. Also, the electrolytic capacitors on the Logic board appear to be intact. So with a simple battery change, this computer is back up and running.
Machine #2, Macintosh Classic II
The non-starting Classic II posed more of a challenge, and knowing from the video series that most of the parts were interchangeable is what really got my excited about this project. By opening both machines and swapping known good parts from the first machine, I was able to determine that the HDD (yet another failed Quantum Fireball), and the Logic Board had problems. Usually on power up, I'd get a black screen, but occasionally, I'd see this...
Upon inspection, the Logic Board had leaking electrolytic capacitors, but once again the battery from 1991 was intact.
Another YouTube channel that's been helpful is Bruce from Branchus Creations. He's prepared many Recapping guides on his website, the one for the Classic II is linked here. I ordered the parts and prepared for a recap of this motherboard to bring it back. As I desoldered the pads, I lifted one, and another was close to failing. I was pretty discouraged because I've already failed in one recapping project, but I kept going. Thankfully I was able to find schematics for this computer linked here, so even if I couldn't identify the nearby via, at least I had a chance to figure out where the pad should be attached.
Anyway, cleaning was a bit of an adventure, and there seem to be alot of cookbooks out there about how to do this. Let me share what I believe to be the best way:
1. Remove old Caps first (hot air appears to be the best way, but I don't have a heat gun yet), Clean the old solder pads with wick, but do not do any repair yet.
1. Remove old Caps first (hot air appears to be the best way, but I don't have a heat gun yet), Clean the old solder pads with wick, but do not do any repair yet.
2. Use Vinegar to clean the board, be liberal with the amount you use, you pretty much want to bathe the board in it to get under the chips and sockets where possible.
3. Use Isopropyl Alcohol to neutralize the vinegar and remove any visible residue from the boards, paying close attention to the pins around the surface mount chips, the finer the pitch of the pins, the easier it is for the junk to short them out.
4. As a final step, wash the board out by itself in the dishwasher.
At this point, if inspection reveals that the board is clean, the sticky residue is gone, and the finest pitch pins don't have any white material between them, then you are ready to move one.
I didn't do these steps in the correct order, and ended up having to repeat steps 2 and 3, but I do know from previous experiences cleaning with vinegar that you don't want to leave it for hours, only minutes because it can do to much damage, so better to repeat steps 2 and 3 than to loose the board.
Anyway, I'm happy to report that after cleaning and recapping the board, I was able to get the system back to life, it was a very exciting moment for me, my first successful recap of a board.
After testing, there is one nagging issue that remains, the sound for this machine isn't working. Since I have the schematics, I've been able to use those to do troubleshooting, I assumed the problem was with my recap, but the circuit is intact now from the speaker output pin (which I know is working with the other board) all the way back to the DFAC but not further, so the adventure continues.
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