Mouse X Y doesn't work

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Mouse X Y doesn't work

Post by Vectrex » Fri May 04, 2018 2:09 pm

Howdy. I've got a 310 with a dodgy mouse. Just trying to diagnose the problem.
- Buttons work
- X Y doesn't work at all. EXCEPT when I move something larger through the sensor than the encoder wheel holes. Like a match or putting bits of bigger tape on the encoder wheels. It'll then move a little bit, otherwise, nothing at all.
- I've reflowed all the solder.
- The ball and wheels physically move ok.
- The leds work (I looked at them through the camera, which you can see below, although they don't seem that bright)
- The voltages are 4.6v (with a few other areas with 1v, 1.6v etc). Is this too low? It's meant to be 5v right? I did fix the power supply 'a bit'. The 12v doesn't work (but it's not needed I think for normal usage without expansions)
- What do the pots do?

Any ideas?

ps do you like my ghetto soldering iron holder? ;)
Last edited by Vectrex on Sun May 06, 2018 11:29 am, edited 1 time in total.

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Re: Mouse X Y doesn't work

Post by davidb » Fri May 04, 2018 4:47 pm

When we had problems with our A3000 mouse - it responded unreliably to motion and appeared to "stick" every now and then - we tested the continuity of the wires in the cable. I seem to remember that the flexing of the cable near the mouse had caused the wires to degrade over time, so we ended up shortening it and resoldering the new end to the contacts on the PCB.

This is all from memory but it might be worth testing the continuity of the cable.

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Re: Mouse X Y doesn't work

Post by dp11 » Fri May 04, 2018 6:24 pm

A few common problems :

1) the cable has breaks in it.
2) the photo diodes have muck on them.
3) the pots need adjusting.( simplest way to do this is with a scope you are aiming for a 50:50 square wave when you move the mouse at a constant speed.

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Re: Mouse X Y doesn't work

Post by atcurtis » Sun May 06, 2018 6:51 am

Going from memory but...
IIRC, there are an odd number of slots in the wheel.
If someone replaced the photodiodes but got the height not even, you don't get the proper quadrature output.

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Re: Mouse X Y doesn't work

Post by 1024MAK » Sun May 06, 2018 12:35 pm

@Vectrex - This type of mouse is a 'bus' type. So you can monitor the digital logic levels sent from the mouse to the computer (if attached). Monitor each of the four lines (two for X direction and two for Y direction) while very slowly moving the 'encoder' wheels. As the wheel is turned the relevant line should switch between logic low and logic high. You can use a logic probe, an oscilloscope, a multimeter or a sensitive LED in series with a 680 ohm to 1k ohm resistor.

There is a nice diagram of the waveforms here

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Re: Mouse X Y doesn't work

Post by tnt23 » Mon May 07, 2018 9:56 am

In my case, one of photo receivers got aged. I've been told a hack to quickly check this: run your mouse with case opened, and use torch or other spot light source on each of receivers in question. Somehow this helps the aged part to run as normal, and identifies the candidates for replacement.
Regards, Tim

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