Leander's Corner

Power Macintosh 8500 Repair

Recently, I won a Power Macintosh 8500/120 in an auction, unfortunately UPS was less than kind with the shipping and it arrived in rather bad shape.

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From the photos it's pretty evident it was not packed well or had an encounter with the underside of a truck on the way to me. The plastics on this era of Macintosh were of low quality and actual oxidize in the environment, much how ferrous materials rust. This results in them being extremely brittle and prone to cracking with age. This was also prime cost cutting Apple time in Apple's history so they did not use a metal frame on these machines, there are many load bearing plastic pieces.

The plastic kibble left over after finding the major components.

Doing a power on test revealed the machine still worked, even booted from the SCSI drive that took a direct hit and was knocked out of its carrier! So my choices were to turn this into a parts machine, try to get some kind of insurance out of UPS (unlikely), eWaste or attempt to mend the plastic. I decided on the last choice. The goal is to have it still be serviceable (those capacitors will need replaced at some point) and have it look presentable. As a rule I don't do RetroBrite since it casues the plastic to turn brittle, something this machine has enough of already, and generally it just re-yellows faster anyway.

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The first task was to reattached the two rear load bearing pieces and reattach the upper parts of the front facia. I used some classic JB Weld due to its higher compression strength along with some fiberglass reinforcement in the rear. On the front and places that can be seen with the case open I used either JB Clear Weld or JB Plastic Weld. The beige color of the Plastic Weld matches the case quite nicely. On the back legs I just wanted as much strength as I could get, after letting the epoxy cure I sanded and trimmed it down a bit so it doesn't look as haphazard.

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Next, I reattached the front facial to the metal shell with some fiberglass and JB Plastic Weld. The downside is I will no longer be able to remove the front panels but given how weak this plastic was I'm not sure that was really an option anyway. The whole top case slides off and allows for access to the internals and drives anyway. However, I'm fairly certain this fiberglass and epoxy is stronger than the plastic that was there in the first place.

This is still a work-in-progress so check back for updates! Next up I've got to reattach the rear plastic panel, I also decided to just flat out replace the broken drive sleds for now.