Macintosh 512K

This computer belongs to a customer, the request was to check the overall machine and specifically low brightness / contrast and service the floppy drive.

Work done

Inspection

Front left

Front right

Back

Opened

Analogue board

Analog board:

There were 2 RIFA paper capacitors on the board, these tend to go bad and explode, so I replaced them with modern equivalents:

Replaced RIFA caps

Aside from 2 Rifa capacitors, the blue axial capacitor tested bad, it looks out of place and was probably replaced at some point. All other capacitors tested good.

Bad Philips cap

When I first powered on the computer, the brightness was very low and the knob on the front couldn't adjust it high enough. I checked a few common resistors, but all tested correct.

After replacing the bad capacitor and adjusting the pots, the brightness was normal again.

Floppy drive

The floppy drive was a bit dirty and all the lubricant had dried up:

Floppy drive

The ejection mechanism was still in good shape:

Gears

Fully disassembled:

Disassembled

All cleaned up and ready to go back together:

Cleaned