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Atari Mouse – Replacing Microswitches

I'd recently acquired an Atari 520STFM (more about that later) and the package came with two mice. One is actually optical and has a switch that allows it to also be used on an Amiga, but it really hated the kitchen bench. I do remember, back in the day, that first-generation optical mice couldn't deal with glossy single-coloured surfaces. The other mouse was the original Atari 2-Button Ball-Mouse. It tracked nicely, but the buttons were as soggy as a wet week?

Open 'Er Up

Very easy to do... two screws up the top-end where the cable enters. Lift at the front, up near the buttons and pull forward to clear the latch at the bottom end.

From here, the microswitches are your PCB-mounted standard, easily available from Jaycar. I toddled off and purchased some of the exact-same replacements, but also two slightly-taller switches. The latter had a much clickier click. The standard replacements were also clickier than the existing switches, but I wanted moar.

A quick look at the circuit board underneath saw that only one side of both microswitches was in use. You can see, per four-hole-mounting of each switch at the top left and top-right of the board, that only the bottom left and bottom right pins are used respectively. The top two are bridged, but the 4th pin on each goes nowhere.

Just because things change over the decades, I quickly checked that my microswitches contacted on the same dimension...

A simple de-soldering saw the old switches out. With the solder removed from the holes in the PCB, I could trial the clearance with the taller switches...

The case was easily re-assembled to test...

But, as you can see, the case wouldn't even close. Testing the buttons, with the case half-ajar, saw them super clicky... maybe toooo-clicky. So I switched in the new same-sized switches (SP0600 from Jaycar) and these were nice!

Although they're not that clicky when they're just in your fingertips in the shop, they're great once mounted in the mouse!

Testing...

All soldered up and plugged in, it was time to test it all out. Previously I had to mash the left-mouse-button a few times to get one click, so I was happy to see that a single click working perfectly!

And yeah, straight into Railroad Tycoon... damn that Grasshopper is a slow first train!