Yamaha MU-01 MSX Mouse Restoration

By Soft Automaton

Resident (51)

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29-09-2021, 17:47

Hi everyone,

Does anyone have schematics (and troubleshooting tips) to restore an old Yamaha / NEOS MU-01 mouse? I found a few but these definitely doesn't work. I'm hoping to recover them. The circuits don't seem all that complicated but I'm new to MSX and well, restoring a mouse is not something I expected to ever really do! I'm experienced with electronics though.

I note that these have different boards inside so it's clear that the MU-01 evolved over time. They are definitely different despite the external appearance being the same.

In case anyone is about to ask about symptoms: the mice don't move at all. I'm certain they need to be cleaned but I can see that moving the wheels manually doesn't allow the mouse to track on screen either. I'm using the Yamaha Midi Recorder as a reference, which supports mouse usage. I'm also open to modding these if that's a thing.

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By sdsnatcher73

Prophet (3406)

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30-09-2021, 02:31

Well certainly mice can fail but the chance of you getting 2 and both being DOA would be small in my opinion. I’ve tested several MSX mice and when they fail it is mostly 1 direction (so 1 optical sensor) that fails.

So let’s look at mouse support in MSX, did you try using port 2 to connect the mouse? Sometimes software supports the mouse only when connected through port 2. Also if you have some way of running DOS the HIDTEST program is a great way to test if a mouse works (HIDTEST uses port 1 though).

By gdx

Enlighted (5595)

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30-09-2021, 11:29

See here:

Most mice are repairable as long as the mechanism and the case are in good condition.

The common cause of failure is a worn connector cable or broken wire when it is not the optical sensor which is bothered by dust and dirt. The optical sensor rarely falls out. On the other hand, it is not easy to find a cable with DB-9 connector sufficiently flexible.

Most of the time the components can be replaced. There are not many.

Here is another example (EGG mouse):

By Soft Automaton

Resident (51)

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02-10-2021, 16:15

Thanks for the insight and links! I would not have found those external links at all.

I'm starting to investigate these and will definitely try the second port to rule anything out. I also came upon this interesting video, which I think may be useful:


I think the MU-01 has the same optical sensor arrangement in it that they are regulated by those resistors. I have to open them up and confirm that

@sdsnatcher73 - in this particular case these are actually well worn AS IS mice from one seller. I'm actually not surprised that they are in bad shape but I'm pretty sure I can salvage them with a bit of effort.

I'll share my findings when I know more. Thanks in advance!

By sd_snatcher

Prophet (3516)

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02-10-2021, 16:15

sdsnatcher73 wrote:

Also if you have some way of running DOS the HIDTEST program is a great way to test if a mouse works (HIDTEST uses port 1 though).

Thanks for the compliment! Smile

But the port-1 is just the default. HIDTEST allows you to select the port 2 too, and other ports/subports. You just have to request that at the command line:


You can check this on the HIDTEST.TXT manual, or type "HIDTEST /?" for this quick help:

HIDTEST [option] [port][subport]
  [option] can be:
    /G: Generic joystick 2-byte mode (disables PnP detection)
  [port] can be:
    0: keyjoystick
    1: joystick port 1
    2: joystick port 2
    P: Light Pen/Touchscreen
  [subport] can be:
    A, B, C or D for the multi-tap
    1 or 2 for the light pen

By Manuel

Ascended (18873)

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02-10-2021, 16:55

https://www.youtube.com/watch?v=NH7_fY16f-c is the definitive guide! :P

By Grauw

Ascended (10604)

Grauw's picture

02-10-2021, 17:55

Hahaha Bas’s first Youtube video and it’s such a troll haha, hilarious. Cool that Bas is making Youtube vids, I’m hoping to see more so I subscribed! (Actual repair videos also welcome Wink.)

By Repair-Bas

Paragon (1155)

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03-10-2021, 08:52

Within a few days more videos

By Soft Automaton

Resident (51)

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05-10-2021, 14:33

@Manual - I saw that! Hahaha! It definitely hooked me in. I'm the one who replied asking about the 'real video', @Repair-Bas Big smile There are no MSX peripherals or parts where I am so repairs are a real thing and everything needs to be purchased from the web.

@sd_snatcher - is HIDTEST built into MSX1 or is that a program I have to get somewhere? I still don't have an SD cartridge yet so I don't have access to ROMs yet. I'm not near the CX right now to find out.