Task: Repair a Nonworking Retro Computer by Replacing the Motherboard
Needed: A working motherboard
Time: 15-30 minutes
Introduction
As you have seen from some of my other posts, I have gotten pretty good at diagnosing and repairing 8-bit computers by fixing traces, replacing components, and soldering in new chips. However, I have little experience fixing 16-bit classic Macintoshes and find them a little intimidating with their surface mounted chips. I recently came across a Mac LCIII that would boot with a nice happy Mac chime but would produce no video signal. I had trouble finding good information online and after digging a troubleshooting I decide to replace the motherboard and punt the repair job for a later date when I have more time to really learn the ins and outs of diagnosing and repairing Macs beyond simple recapping which I have previously done.
Instructions
The good news is that there are often fully populated and functioning motherboards of all types available for sale on eBay and from other sources. I purchased by LCIII replacement motherboard from the seller Vintagemacs on eBay who, as the name implies, specializes in vintage Macs. There are lots of working Macintosh motherboards available on eBay in addition to others such as Commodore and Atari. I was able to get the working replacement board for a little over $200 including tax and shipping. The board arrived in good shape and booted right up! I now have a happy Mac LCIII and a future repair project.
Comments
Replacing a motherboard is definitely more expensive than fixing it yourself. For example, working Commodore 64 motherboards sell for $100 to $150 on eBay. Replacement chips might only cost you $25 to $50. However, a motherboard is cheaper than buying the whole computer and might be a good compromise when the repair is beyond our skills or you simply want a working system and don’t have the time to take a deep dive repair.
Below is the LCIII booting into Mac OS 7.5.1 from a Bluescsi hard drive emulator.
