[sdiy] 19" rack mounted & modified Atari Mega STe

[Hallvard Tangeraas]

On 15/2/07 21:29, m.bareille at free.fr wrote:

> I did the same thing almost 10 years ago with a boosted Falcon 030 re-housed
> into a 19" 3U rack case.

That's awesome! You've done a great job.
I took a look at the rest of your site and you do indeed have some great 
projects there.
Glad to see others having rack-mounted their Ataris as well ;-)



>> 1) the main board is too wide to fit the 19" rack standard
> 
> Exact , the ST/STe/falcon boards are too wide ... so i have cleanly unsoldered
> all the sockeds on the left side of the board

Ouch! I first thought about doing the same thing, but quickly found out 
that I would have to cut away a little bit of the circuit board in 
addition to removing all the rear connectors. Too risky with a PCB 
consisting of several layers, and a lot of work of course.
It took me forever to come up with the simple idea of just flipping the 
PCB 90 degrees round!

Up until recently I still thought removing the connectors was the way to 
go, then move them to the rear panl with IDC flat-cables etc. But why 
make it so complicated? So I've decided that the simplest thing will be 
to leave just about all the connectors as they are on the Atari PCB, 
then make small extension-boards that go to the back-panel of the rack 
enclosure and connected to their original connectors via flat-cabling.
In addition to not having to desolder the existing connectors this 
method also makes it easy to swap the mainboard in case the computer is 
damaged somehow.

I've also spent time checking about the 19" rack standard and am glad to 
have found out that there is no specified standard for the *depth* of a 
19" rack (I mean the cabinet, flight-case or whatever where you place 
the synth-modules and so on). Furthermore I've heard that racked 
computer equipment (servers etc.) came come as deep as 100cm!
So 50 or 60cm should probably be fine. But where do i find empty rack 
enclosures that deep?




> 
>> 2) The front and rear panel will have lots of LEDs, connectors, knobs
>> and switches. Any experiences with laser cutting? Is it expensive?
> 
> 
> Leaser cutting on demand is a very expensive service . You also will need to
> provide a dxf file for the cuttings ... Do not expect to do that with a small
> engraving laser ( <100W) . Those devices do not cut steel, just thin wood
> ,plastics  or paper..

DXF; that's autoCAD?
I have a relative who uses that program professionaly though I haven't 
the faintest idea how to use it.

I heard that there are also other methods of cutting metal now, but 
can't remember the details. Sand cutting or something?
Since I have several other projects waiting I think it might be a good 
idea to get the cutting for all my projects ready and do it in one go. 
If it's not too expensive it'll probably be cheaper to have it all 
finished at once.



> It is perfectly possible to do that with your two hands a good metal saw , limes
> , and a pair of drillers ( dremel and a bigger one ) . That's what i did . It
> was a very hard work and it took me many days to achieve it.  But very cheap
> too...

I don't have too much experience when it comes to metal-workshop. I've 
made some mistakes when cutting metal before and it's very frustrating 
to experience that you have one go at it. If you make a mistake you have 
to live with it. With such a big project as this I really want it to 
look nice :-)
Yes, I admit it -I am a perfectionist ;-)


> I have mounted some old pictures i had of this unit on my site at
> http://m.bareille.free.fr/falcon030/mb_falcon.html

That really is great piece of work! You should be proud of that.


> I let ATARI specialists to identify the add-ons ;)

hehe ;-)
I don't know of anyone ;-)
Lots of goodies there!

Talking about my add-ons. As this will be a specialized "MIDI computer" 
I will rely heavily on the cartridge-port for 4 or 5 daisy-chained 
devices! A cartridge-port expander, a MIDI port expander, SMPTE sync, a 
backup-device cartridge and one or two more which I've forgotten about. 
I will also be adding 3 MIDI ports from one of the serial (modem) ports.
Since the cartridge connector is the most unreliable part of the whole 
system I will hard-wire it when everything is checked to be working. 
That's probably the only connectors that I won't continue using because 
they "wiggle" too easily. Very frustrating when copy-protected software 
freezes because the dongle has wiggled a little bit or one of its pins 
are dirty.



> 4) Mecanorma transfert letters on my Falcon , with a thin layer of transparent
> acrylic varnish spray ... After more than 10 years the thing is still clean :)

I haven't heard of Mecanorma -are they "rub-on" letters like Letraset?
I used those in the 80s when I started out with electronics. Hard to get 
the letters aligned properly, but looking good when it worked!

I know that Schaeffer (http://www.schaeffer-ag.de) does front-panels, 
both cutting and printing, but from what I could see they're not exactly 
cheap. And on top of that I'll have to pay a hefty fee for postage 
(seems they only use UPS and not standard mail) and import duties/taxes 
when the panels arrive here.



> Well i hope my pictures will inspire you :) Good luck !

Thanks, they sure do.
I'm still trying to learn how to master "Eagle" 
(http://www.cadsoftusa.com/) which seems to be a great program, but 
complicated if you've never done this sort of thing before. But once I 
finish all those PCB designs (I also need to complete some PCBs for a 
vocoder I'm working on, which is another big project) I will get them 
etched somewhere (I've tried it several times myself without much 
success, which is why I want to try to leave it to others, providing the 
cost isn't too high). By the way, from your page it seems you also etch 
PCBs? Is that just PCBs for projects you've designed, or can you make 
PCBs for anything? I just need a few small and simple single-sided PCBs 
which I'll be designing with Eagle, and some small PCBs taken from 
magazine articles (photo-copies, but touched-up by me to remove copy 
errors etc.).


Great to be on this list! :-)


Hallvard