[sdiy] use pc psu's as EMI chassis for synth modules

cheater cheater cheater00 at gmail.com
Fri Nov 26 21:32:53 CET 2010

Hi guys,
I've had a look at those old broken power supplies that will never
come to life, and I have had the perfect idea - you can use the
chassis for something nice! It's much shorter than one dotcom unit,
and a bit wider. More like 1 1/2 dotcom unit wide, or just under 2U of
MOTM. Still, most of the modules could probably fit in very easily.

- the module is nicely shielded from others and from outside interference
- the module gets some nice thermal stability
- if the module gets very hot, you can mount a Noctua P12 fan
(inaudible) and cool it
- the module is sturdier. It can sit on a shelf without you fearing
that the fragile PCBs will be destroyed.
- the module doesn't have wires sticking out! Installing new modules
and messing about inside a synth while it's turned on is not a problem
- generally, electrical safety is a big plus.
- you get a nice, sturdy frame for your module.
- the metal is usually just thick enough to be sturdy, but it's thin
enough to be easily punched.


OK, those things are big, but then you don't have to use em for every module.

Regarding panel size etc: you can have one of several options:

1. use this size as your modular's panel size. Easy.
2. Dotcom: Use a cheap plastic panel and mount it to the chassis
stand-offs of about 1". This does two things: it gives you space to
mount front-panel controls; and additionally, if your module
front-panel is not as wide as the ex-powersupply chassis, you can
mount another, shallow, module next to it
3. Dotcom: use a cheap plastic panel and simply screw it onto the chassis.
4. Dotcom: take one row of your Dotcom chassis, and fill it with
modules of exactly this height. Use the remaining space for mults etc.
5. Eurorack: The side plate is slightly higher than eurorack. It's
also exactly 8 cm wide. Use the thing as a portable 4U eurorack synth.
Or, if your modules are not deep at all, then you can use it as 7U.
There's enough space there to house a small PSU as well, based off
e.g. a couple laptop power supplies (they have very flat toroids).
Even better, you get an IEC plug, and usually a fuse holder, so that
you don't need to take care of that.
6. Fracrack: same as Eurorack. Houses 1U of a deep module, or nearly
2U of fairly shallow modules. Having a tiny amount of overhang
(0.125") on the side shouldn't bother anyone.

Happy hacking!

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