In my last blog post, I wrote about the four computers given to me by a retiring computer repair store owner – one of which is a Macintosh Color Classic. Some people say that the screen on the Color Classic is super crisp and that makes this Mac pretty collectible. It has a 68030 16MHz CPU, supports 10MB RAM, and came stock with a 40, 80 or 120 MB hard drive. This one had an 80MB drive in it and 6MB RAM, 4 onboard, and two 1MB 30-pin SIMMS installed.
When I first got it home, I opened up the little access door on the rear panel, pulled out the logic board and removed the battery. If you learn one thing from my blog and one thing only, REMOVE THE BATTERY FROM YOUR OLD MAC COMPUTERS. Most of the original batteries in these computers are known to burst in a very dramatic fashion and destroy the logic boards. You may be saying “What’s the worst that can happen?” Well, take a peak at this Maxell battery that was in the first Mac SE that I restored. I was able to restore this one, but I was really lucky. Search the net, it gets much much worse.
Don’t learn this the hard way – just don’t do it.
Next, I cleaned the logic board very thoroughly. I scrubbed the logic board with 91% isopropyl alcohol and an old toothbrush, then I soaked it overnight in some warm water. After this, I let it drip dry for several hours and then I scrubbed it with the alcohol again and let it dry once more. The board at this point was looking like new.
After this, I proceeded to remove all of the old capacitors, as this type of capacitor is known to leak electrolytic goo and eat the pads and traces right off of the circuit boards. When I removed them, the pads and traces underneath all looked good and I thought that there was not going to be any residual damage.
I ordered all tantalum solid caps, to avoid having any future electrolytic failures in the future. On the 68MLA forum, there is a very handy link to Digikey that has all of the capacitors you need in a saved cart. I placed my order and waited about 3 days for shipping.
When I got the new caps in the mail, I installed them and while they went in very easily, I did find that the two pads on C4 were both lifted from the board and I was unable to save them. I was able to solder the new cap back to the traces themselves, but I will have to revisit this capacitor at some point in the near future. None the less, the board was restored and it was time to test it out. I did a quick power up and everything held onto it’s magic smoke! No smells, no fires, no sparks! Now it was time to deal with the hard drive.
The first time I plugged the computer in to evaluate it, the hard drive would only work intermittently, so I knew that there would be some issues with it. Now that I had the logic board repaired it was time to check into this. I pulled it from the computer and connected a known good SCSI hard drive that I had been using in an outboard drive enclosure with another mac – that drive worked fine from the external enclosure but when I tried it from the internal cables, it would read but not write. Hmmm… something was wrong here. Could it be the capacitor C4? I rechecked it and decided that it was as good as it was going to get. Then I examined the difference between the two drives – one, a Quantum 80MB, known for suffering from something called ‘Stiction’ which as far as I can tell, is where the rubber bump-stop for the drive’s heads get soft and break down and stick to the platter. This, I was told by a patron over at 68kmla.org called EvilCapitalist, is what my 80MB drive was experiencing. My Quantum Fireball 1280MB drive, on the other hand, was having completely different issues. It was being detected, would boot, and I could write to it via the external SCSI drive enclosure. Once transferred into the internal drive cabling, I lost the ability to write to it. What was different between the external and internal environments… Termination! The external box had an external SCSI active terminator plugged into it. I found and set the termination jumper on the 1280MB drive and – bingo! It worked perfectly! Now my new Color Classic was complete! I loaded up a clean install of System 7.1, added System Update 3, Stuffit, Disk Copy 6, Connectix RamDoubler and a few games and so far, it has been as stable as a brand new computer. I installed the iOmega Zip Tools and connected my external 4GB drive and 100MB Zip Drive as well.
I will still have to address those lifted pads and that work around I did on C4 though…