STM1 mouse repair questions

[danboid]

I already had a working PS/2 to Atari and Amiga mouse adapter but I wanted ye olde Atari mouse too so I bought an "untested" one off ebay and guess what? Yes you guessed correctly but at least the left mouse button worked.

As for repairing it I have these questions:

The cable of the STM1 is very wee. Does the cable need to be under a certain length for it to work, is that why its cable is so short and mine still isn't working after I've replaced the cable with a longer one? I currently get a flashing cursor that doesn't move. My multimeter told me the cable needed to be replaced, at least.

It seems I have a rev e version of the mouse so this makes me think there were at least 5 versions of the ST mouse?

I have found this schematic for how the ST mouse cable is wired but they neglected to say which revision of the mouse this wiring is for and they even went as far as spelling Atari wrong too:

https://www.atari-forum.com/viewtopic.php?p=101281

Does anyone know if this is the correct wiring for a rev e STM1 mouse? Did all the revision of the Atari mouse use this same wiring?

[stephen_usher]

There are multiple versions, probably made by different sub-contractors. There are at least two different lower half designs, one with the ball dome moulded into the case and other where the ball dome is a separate item screwed into the case. The PCBs will probably be all different.

Of course, they all have the same model number.

[rubber_jonnie]

As @stephen_usher says, there are likely multiple iterations of PCB and physical hardware, so what would probably help here are photo's of both side of the PCB and the case parts etc. Make sure they are well lit and of decent resolution so they are clear.

I'd also add that it is possible that the cable may have variance in the colour wires used, so don't take it as read that they will be the same mouse to mouse.

Make sure any photos are uploaded here and not linked to other sites as links often break. Once uploaded you can add them inline in your posts.

I have 2 STM1 mice, both of which work, so if you can get pics uploaded, I can see if mine match yours and buzz out the cables so you at least know what on the 9 pin plug goes where in the mouse.

[danboid]

STM1-top.jpg

STM1-bottom.jpg

[rubber_jonnie]

STM1-top.jpg


STM1-bottom.jpg

Cool, I'll go and check mine a bit later and let you know if mine are the same. In the meantime, if you've not already done so, I'd suggest using a multimeter to check continuity from the plug to the solder points and draw a map of what works and what doesn't.

I'd also suggest a look over the bottom of the PCB with a magnifying glass to look for bad solder joints and be aware that the mouse probably won't work oitside of the case as the sensors will probably be swamped with ambient light.

Also I'd wash the ball with dish soap and hot water to degrease it and carefully remove the shutter spindles and clean the rollers, then blow off the whole board with compressed air to ensure there is no debris obstructing the sensors.

The LM339 IC is a quad comparator, cheap as chips to replace, and the most likely component to have failed if it isn't the cable, but I'd go for that last of all as my money is on the cable.

From your post I'm assuming your joystick/mouse port is OK since the PS/2 adapter and mouse work fine.

[danboid]

Thanks RJ!

Yes, my ports are both fine as I have a PS/2 mouse adapter, 2 original Atari joysticks from my VCS and some joystick adapters for Mega Drive and SNES controllers.

[rubber_jonnie]

OK, so neither of my mice match yours...

IMG20241027141331.jpg

The LM339 is surface mount and on the underside and the wiring colours, whilst matching on mine, are different to yours. I think yours is a very early model based on the brown PCB and lack of a plug for the cable.

My best suggestion at this point is my original one of using a multimeter in continuity mode to check the cable from plug to mouse.

I did try and map mine but the results were kind of odd even though the mouse works just fine, so I won't post them in case it confuses things even more.

[stephen_usher]

This Czech blog shows four types of mouse... http://www.krupkaj.cz/sblog/article_det ... id=9000017

This is an image from that blog post...

STM1-vnitrek.jpeg

Yours looks the closest to the third one along.

[danboid]

This Czech blog shows four types of mouse... http://www.krupkaj.cz/sblog/article_det ... id=9000017

This is an image from that blog post...

STM1-vnitrek.jpeg

Yours looks the closest to the third one along.

Thanks Stephen

There is a pinout table on that page but I'm not quite sure what it means or how they've numbered the pads on the PCB.

[danboid]

My best suggestion at this point is my original one of using a multimeter in continuity mode to check the cable from plug to mouse.

That's the first thing I did. When I couldn't beep out a few of the wires, I tried to hack away at the port end of the mouse connector to get a better view of the wiring but getting in there was much more tricky than I thought and I severed at least one wire and cut at least one finger trying to expose the wiring. It really wasn't the best technique, I should've just stripped the wires.