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Lisa 2 mouse only works on one axis

falter

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I'm not sure where my issue would be here - I fired up my Lisa 2 for its monthly check.. and the mouse pointer when the mouse is moved immediately gets pegged at the top of the screen. I can move left or right but not up or down. I've opened the mouse up, removed dust/debris, checked that the appropriate rollers move.. and they do.. and the pointer *does* react when you do straight up or down, but it just bounces in place.

Is there anything inside the computer that might be the issue here?
 

stepleton

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Could be a number of things... The Lisa mouse is a quadrature mouse (basically the same as a "bus mouse") and so there are two signal lines each for horizontal and vertical motion. (See pinout here.) If one of the two lines for vertical motion isn't working, then you might see something like what you see here.

The fact that it bounces up at the top of the screen suggests to me that the problem probably isn't in the mouse itself, but if you wanted to confirm that, you could hack up a little "adaptor" cable that swaps the X pins with the Y pins. If you see the same behaviour (albeit with up/down motions of the mouse now making the mouse pointer move right and left), then it's not the mouse.

So once you have localised the problem to the inside of the computer, then you've got a few potential culprits. If you've had a battery leak in your Lisa, then the card edge connector on the motherboard that receives the I/O board (the closest board to the back of the computer) could be corroded or hopefully just dirty.

And if it's not that, then there's some pullups and a 74LS153 (see location D2 on schematic page 2) between the mouse port and the COPS, the Lisa's microcontroller for keyboard/mouse/power button/RTC. If the COPS were broken then a lot of other things wouldn't work, so I suspect that the problem lies somewhere between the COPS and the mouse port on the back of the Lisa.

See also PDF page 223 of this copy of the Lisa Hardware Manual.
 

NeXT

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Plug it into any other 9 pin mac and see what it does. The Lisa, Macintosh and Apple II mice were for the most part interchangeable.

Also if you are running a 2/5 that was converted from a Lisa 1 you have the old style AMP connector for the original Lisa mouse which is a poor fit and lacks thumbscrews for the later mouse. I removed and replaced that with a proper D-sub connector.
 

VERAULT

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Hey NEXT are there any FIX procedures for these quadrature mice? Since they have gotten pricey its tough getting them. I have bought at least 3 since Covid that came with one axis not working but I never found much info in the area of repair. I am guessing this is going to get worse for alot of them.
 

NeXT

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I've not actually looked. Admittedly I only own four of the 9 pin mice but I've yet to run across one that had a bad axis. They are such simple devices other than failing IR led's and phototransistors that beyond mechanically wearing out I don't think there's much in them to fail that is impossible to still buy.
 

falter

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Dang. So I pulled out my Mac Plus mouse and plugged into the Lisa.. and yeah, all the axes work. So it's the mouse... ungh. I wonder if I can fix that somehow.

I'm kind of thinking this may be a wire break somewhere. One time when I was moving things around the mouse fell off the table rather violently.. maybe it pinched something.
 

daver2

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You can usually ‘see’ if the IR transmitters themselves are working with a video camera. Their response usually extends into the infrared spectrum and appears as a light spot on the screen (or at least the old monochrome cameras used to at any rate).

Dave
 

falter

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Also, I assume this is the AMP-style connector NeXT was talking about? I've long suspected this was an original Lisa 1 machine. It came to me set up as a Mac XL, and it does not have the B prefix for serial number, but it has a low Applenet number, this mouse, and the floppy drive has the improvised adapter with shims used to get the level right. I read somewhere the presence of that also leaned towards it being an ex-Lisa 1.

20220122_170610.jpg
 

NeXT

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Yeah that's the connector. Long out of production and a pain to work with, but if you have an original Lisa mouse like you do I'd leave it alone.
 

daver2

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So the transmitters are OK then.

You should now be able to find the corresponding IR receivers and look at the outputs with your oscilloscope. One pin should be at a supply rail but the other should change as you rotate the ball.

Dave
 

falter

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I found the supply rail but the other side... i don't know if I'm doing something wrong or it's just stone dead but there's nothing going on there.

I'm assuming options for replacing the transmitter are fairly limited?
 

VERAULT

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No you can probably modify it with a new part if you line it up. IT would take some precise fitting. I wouldnt give up on a lisa mouse. They although being the same as an apple II mouse, are stupidly hard to come by. I only have the one myself.
 

daver2

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This may just be a photodiode - so look at the non-power rail of the receiver with your oscilloscope set to AC and an increased sensitivity.

Can you find any markings on the sensor and identify a data sheet for the part?

Can we get a better (optical) picture of what is in post #10 please. I would have expected to see two rotating radial grids between each of the sensors. I am not sure what I am now looking at in the photograph?

Dave
 

NeXT

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Since you are in Vancouver I've been trying not to solicit anything but I do know people who would be willing to help locally if you need secondary opinions from someone local.
 

VERAULT

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Also this may seem obvious. but since you can see all 4 IR leds lit (post 10 the top two are very faint, may be just a bad photo) could it be possibe there is a bit of dirt or obstruction in the way?
 

daver2

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It begs the question why there are four IR LEDs when two will suffice for a quadrature detector...

Dave
 
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