Cheetah 125+ Joystick Repairs

I recently bought a large job lot of vintage computer equipment, among which were about twenty joysticks in varying condition.

These had been stored for decades and required a good clean-up; all worked fine except for four Cheetah 125+ models, which had varying problems.

One of the offending Cheetah 125+ joysticks.

A couple of them were in their original boxes, and I really hate writing equipment off for spares unnecessarily, so I figured I’d have a go at repairing them.

Most joysticks are a fairly simple construction, these ones included – only four case screws hold the bottom on, revealing the inside.

Joystick internal construction.

Some quotes from one of the boxes, which I found entertaining: “deluxe”; “robust construction”; “rugged hand grip”; “heavy-duty base”; “highly sensitive, light touch fire buttons”; “extra-strong direction/fire contacts”.

As you can see from the image above, this thing is cheaply-made garbage!

The side of one of the boxes, which makes some exorbitant claims.

Rather than using micro-switches like the more professional joysticks (i.e. ZipStiks), each direction uses a leaf-style contact, and the secondary fire buttons are just a sprung metal disc taped over a contact on the PCB – these methods are less reliable than switches, and make the joystick feel very limp, rattley, and unintuitive.

Joystick #1

Joystick #1 had intermittent left and right directions, and whilst the triggers worked fine, neither of the secondary fire buttons worked.

Cleaning off the underside of all the leaf contacts with a nail file fixed the direction issue, and removing, cleaning, and re-installing the button contacts fixed the button issue. 100% OK!

Joystick #2

Joystick #2 had no working directions, and whilst the triggers worked fine, neither of the secondary fire buttons worked.

After dismantling the joystick, I noticed that all the screws which contact with the leaf springs to form a switch were coated in rust – this was probably caused by long-term storage in a humid environment.

Soaking these in white vinegar overnight then reinstalling, then cleaning off the underside of all the leaf contacts with a nail file fixed the direction issue. Removing, cleaning, and re-installing the button contacts also fixed the button issue. 100% OK!

Joystick #3

Joystick #3 had non-working left and right directions, and whilst the triggers worked fine, only one of the secondary fire buttons worked.

Removing, cleaning, and re-installing the button contacts fixed the button issue. However, cleaning off the underside of all the leaf contacts and topside of the contact screws with a nail file did not resolve the left direction issue, nor did tightening all of the connections or adjusting each of the springs, though I was able to get the right direction working again.

At this point, it made sense to check for electrical continuity between the switch output and the joystick connector (using a spare male connector to make the pins easily accessible for testing).

On all Atari-compatible joysticks, the connector has four digital outputs for directional data (up, down, left, right), one digital output for fire (some joysticks also have an auto-fire feature or multiple fire buttons, which are wired in parallel), and two analogue outputs for paddle signals.

Atari-compatible joystick connector pin-out (image credit: AtariAge).

In this case, there turned out to be a break in the left-direction wire somewhere between the connector and the cable entry into the joystick, probably caused by cable stress – this is not easily repairable, so I’ve confined this joystick to spares.

Joystick #4

Joystick #4 had non-working up and down directions, and whilst the secondary fire buttons worked fine, neither of the triggers worked, and both felt really notchy – the case also had some cracks, so I suspect that this one has been crushed or dropped at some point.

After dismantling the shaft to try and repair the triggers, I found irreparable damage to the trigger mounts, so I’ve confined this joystick to spares.

Conclusion

Looking for a serviced joystick for your Atari-compatible computer or console, or want to try and repair one of the spares ones? All of these joysticks are currently available for sale on my eBay page.

Published by themightymadman

A conscientious, intelligent and committed graduate engineer, with excellent interpersonal skills, an eye for detail and a keen interest in hardware design, mathematics, and software development.

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