exxos's Atari, Amiga & retro forum

'A' goes against the PCB, the other ends are cone shaped to fit tightly against the opposite shape in turned pin sockets.

Still working on my STacy... :)

I previously had a 1.44 HD floppy mod in it and it worked fine until just recently. Since I've got it apart I removed it. I've
currently just got the bog-standard 720k floppy that came with the floppy in place.

I'd really like to go back to the 1.44 HD setup if I could though. I'm a bit worried about space underneath the STacy's floppy drive/
hard drive cage but it might just fit in there.

I've already got the mod itself (see earlier in the thread where I put it together there). I just ordered the cable and Sony MPF
drive from Exxo's store so I should have everything I need once they get here.

Now, I was looking at the guide and it does list STFM and STe. Of course, the STacy is going to be different. I looked over the guide
and tried to match it up to the STacy's motherboard but I've not really been able to find the connections that would match up.

Has anyone else done this with a STacy? It would be nice to be able to draw on someone else's experience with this.

Here's the STacy's motherboard:


Thanks all.

Well, thanks for the pictures, appreciated.

I'm looking at my STacy's motherboard and I just don't see a "W301" anywhere. :(

I'm lousy at reading schematics but if I was to hazard a guess from this picture,
what is needed is somewhere around U28?

You just connect the wires to the sound chip as shown in the last image..

Okay thanks. Just trying to familiarize myself with everything
before the drive and cable gets here.

Okay, now everyone remembers that I'm easily confused, right? :lol:

Okay, bearing that in mind, I attempted to pull up the YM2149 pinouts and got this:


Which, to my inexperienced eye, doesn't look similar to the schematics we've posted
here. I mean, pins 19/20 on the above doesn't seem to correlate with the schematics.
Of course, I'm probably just looking at it wrong. :roll:

Pin1 is easy to find on the above, and it's easy to find on the actual picture of the chip,
but I'm not sure where it's at on the schematic and where pins 19/20 actually are on the
picture below?


Thanks all.

Hello,

The picture of the pinout that you posted show the physical layout of the pins, or in other words, it's a map of the real chip. That's why you find easily the pins.

On the schematics, the pins are laid out by function/role, and if possible, input pins are on the left side, output pins are of the right side, and there may be other heuristics ; each pin on the symbol has a name (inside the box) AND an pin number (outside the box) to find the actual pin on an actual chip ; but in other words, it's a mess when confronting the schematics against the real thing. (Add to the mix that annotations are handwritten on those old schematics)

Here I have put the annotation in RED where they are :


As a side note, that's the very reason why I took the effort to create symbols that reproduce the physical layout of the pins instead of the "classical" view, because that would make it easier when servicing the computer, at least for hobbyists like myself that does not want to wreck my brain each time I try to map what I would read on the schematics on the real thing.


On the STE that was my first work, I left the chips on their own, using (and abusing) wire names so that Kicad connect the dots :


On the 260/520ST that is my third work, I try to visually wire elements that are of the same subsheet, so that it is less abstract :

Thank you. :)

I actually could sort out 19 and 20 on the schematics but as you surmised, I
was having trouble figuring out exactly where that is on the actual chip itself.

The Dsel annotations were confusing to me too, as they are literally listed at
pins 19,20, on the bottom left of the chip.

So if I was being quite literal, going down the right side of the YM-2149, from
top to bottom, pins 19 and 20 in red would be pins 9 and 10, counting down (not the
actual pin numbers).

BTW, the PDF you released for the RSVE mod remake covered this in most
excellent detail - even a cantankerous old crock like me could figure out
where the necessary pins were! :lol:

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