Doesn’t want to boot up. When the power button is on, I can hear the high voltage kick in. When I press the power button on the keyboard, the power light and fan comes on, but no picture on screen. The SCSI drive does chirp every few seconds. Recapped logic board, removed and cleaned under L1, L2, and U1. All looked fine. Confirmed it was a problem with the logic board by putting a Color Classic logic board in the machine and confirming the analog board and CRT are fine. Machine works fine with known good logic board.

The LC 550 replaced the 520 with a faster 33 MHz 68030 and 4MB of RAM standard. In 1993 and 1994, it was the all-in-one Mac in most elementary school classrooms — familiar, reliable, and capable enough to run Oregon Trail, ClarisWorks, and HyperCard simultaneously. Millions of children learned to type on machines exactly like this one.

• Logic Board Recap — Feb 14, 2024

• EveryMac