Chosen Solution

I have a late 1991 Macintosh Classic, running System 7.0.1. I bought it on eBay in January. Starting since around May, it’s been having problems turning on. When it doesn’t work, it shows a striped pattern and flickers the Sad Mac. When it does work, it boots System 7 perfectly as if nothing ever happened. Sometimes it works and sometimes it doesn’t. It came with a printer and cost a hundred bucks, so I don’t want a Style Writer or my hundred bucks to go to waste!

We used to regularly rebuild the power supplies and replace the logic board capacitors. Here’s a video on removing the logic board capacitors in three minutes: http://www.youtube.com/watch?v=5VjtzugrI… We used to be able to buy the capacitor repair kits for $15 Here’s a very good article on diagnostics and what to repair on an SE/30 which will work fine for the classic. http://www.jagshouse.com/classicrepair.h… Just watch out for the end of the CRT as it will break easily and also knock you on your butt if not discharged. Here’s a gutsy logic board cleaning method I have not tried: http://www.youtube.com/watch?v=idnD9DHFU…

You might want to crack it open, and check for any damage or debris on the motherboard, power supply, or display driver board. You should also check the connections to/from the motherboard

That’s OK, I reinstalled the operating system and now it’s OK.

Here’s my diagnosis: It’s the Sosumi Mac! What you can do: DISCLAIMER - YOU CAN’T BLAME ME FOR KILLING YOURSELF, THE CRT IS DANGEROUS, THIS WHOLE OPERATION IS DANGEROUS. BE WARNED.

  1. Open up your Mac Classic.
  2. Remove the logic board (motherboard) from the machine and disconnect all cables connected to it.
  3. Remove the PRAM battery, RAM modules. DON’T FREAK OUT ON THESE NEXT STEPS, IT MIGHT SAVE YOUR MAC.
  4. Take a tub of warm soapy water, toothbrush, and your logic board.
  5. Submerge the logic board into the soapy water and brush with the toothbrush around the capacitors. Give the whole logic board a thorough cleaning.
  6. Rinse very well with clean water in the tub and scrub the logic board down with the toothbrush again.
  7. Try to dry off the logic board as much as you can, and let it sit in a shady area (not sunny - you could fry it) for AT LEAST 1 WEEK. YES, ONE WEEK.
  8. Pop the logic board back into your Mac and you should be fine. Hope this helps!