Posts by Chordprog

Quote from Jens

oops - my bad

Yes, please report back. We don't have too many Atari customers yet, and this would be my first-ever-remote-repair of an ST.

I was shocked when the mouse showed up yesterday, after only one or two days in shipping. But the mystery is slowly unraveling here. Yes, the problem still occurs with the Atari mouse. (A pricy rule out for sure). But then something you said before triggered my mind to start pressing on the keyboard. And Eureka! It seems that when I put any significant amount of pressure just above the number pad, the problem corrects itself. This area is around where the LS244N chip would be, and also the mouse port connectors. So this would lead me to believe that yes, the problem may just be a cold solder joint. Why couldn’t I have tried that last week? <facepalm>. So the conclusion is that micromys didn’t cause the problem. Or did it?! Now that I’m thinking about it, the device never quite fit properly on the underside of the keyboard. I always thought to myself, it’s not really made for Atari ST, because it was always rather forced into position with the black box hardly able to make it out from underneath the front of the computer. I.e. it was definitely putting undue pressure on the mouse port itself. Until I got a DB9 ribbon extension to fix the problem a few years later.

Anyway I’m not here to blame, and I understand you’re on v5 now anyway. And it may all just be due to old age for all we know. I’ll open her up and check for cold solder joints and that should fix the problem I hope.

Very informative! Thanks.

The price is for 5 chips, so maybe it’s not quite as bad as you suspect.

I’ll report back in 1-2 weeks with the results of the new mouse and/or chip replacement.

yeah I don’t have any ice spray. But you’ve helped narrow down the mostly likely problem!

MM74HCT244N

I ordered these at an excellent price along with some dip20 sockets. Hopefully these are the compatible chips and will solve the problem. I’ll still wait for the Truemouse and see if that solves it before I go soldering the keyboard. It looks like an easy procedure, but the last thing I need is to lift a tracing or do something stupid that causes more problems.

Atari ST Keyboard Repair

yes according to this video, he seems to be having a very similar problem as me. And shows the correct chip being replaced. Interesting that my issue is always after like a period of consistent use. Ie it always works fine in the beginning.

Also there are many LS244 chips on the ste motherboard. I have no idea which one controls the mouse. It will require more research and maybe a post to the Atari forums. Thx

Quote from Jens

Just checked the ST keyboard schematics - if the whole keyboard continues to work, then the LS244 chip is the culprit. Exchange that, and your problem is most likely gone. You can also use a HC244 or HCT244 chip, whatever the local electronics store has in stock in DIP20 package.

Thank you kindly for that information. Is it at all common for these chips to burn out?. Could the chip get confused if being sent information too fast? I remember the original Atari mouse was very slow and this ps/2 mouse feels like 4 times as fast. Could a buffer overflow be causing the problems I’ve described? I was thinking to still buy a native Atari compatible mouse to give it a go before doing this chip change.

if the problem was the keyboard controller , then the keys would also have problems? Keyboard is 100% all the time.

If it was cold solder joints , then things tend to get better when heating up, not other way around? Cold boot tends to fix the problem. Although one time it didn’t until I pulled ps/2 mouse from micromys, and reinserted it. Then it worked again.

I’ve done some basic soldering and do own a multimeter , so as long as I know what pins to touch I could easily take a reading.

Quote from Jens

Again, if three out of four directions work as expected, it can't possibly be Micromys. One direction always uses two signals at the same time, and a movement always requires both to toggle in a certain sequence. Only the sequence determines "movement or not", and the order of signals toggling will tell the computer (or in case of the ST: The keyboard MCU) the direction. If you are interested in the technical details, look up "in-phase and quadrature signals".

I don’t think it’s 3 out of 4 directions working normally. The first symptom is usually any horizontal movement of the mouse (ie left or right) will only move the mouse in one direction. So , for example, I could be moving the mouse left or right, but either way moves cursor to the right. Vertical movement will continue to work for a short time but then even the response on that goes wacky too.

Quote from Jens

To be honest, I'd try a genuine ST mouse first (maybe you can borrow one?) and see if have the same issue. And if so, there may be a piece of software that gets in the way, or the keyboard MCU has a problem that shows after 15 minutes. You may know that the keyboard MCU is passing the mouse information to the main system in an ST.

Thank you for the troubleshooting Jens. I had a genuine Atari ST mouse but found it to be extremely sluggish, and since put it into storage, and now I can’t find it. Ugh. Anyway, the only software I use is Notator by c-lab. The problem seems to manifest after doing multiple keyboard/mouse combination commands, like “hold control key and move mouse over the value to sweep values” or “click and drag while holding alternate key” , but I’ve been unable to troubleshoot what exactly triggers the problem. Sometimes I’ll just press a few keys and the problem resolves temporarily. But everything will work fine for a while. Are you saying there is no chance it’s the micromys? I know the Notator program has a built in mouse accelerator. I don’t use any extra startup software or drivers.

Not sure if it‘s my micromys v3 or what but im finding that after a bit of consistent kb & mouse use, my mouse tracking always seems to go crazy. Mostly on the horizontal axis. Like moving in either horizontal direction will only move the cursor one way. I tried a second ps/2 mouse and get the same results. Only a cold boot seems to fix the issue. This converter is fairly old but I’m not sure if I should buy a newer ps/2 converter (fairly cheap) or just bite the bullet and spend the $60+ on an actual atari st compatible mouse.