Used case power question

Hi there,

I bought this used case and I know what I think I see and what I need, but it'd be nice to have some experienced input.

Here are some images (the last one is probably the best):

https://imgur.com/a/1mL8PGt

So what I think I see is a bunch of distribution boards and no power supply. I think I see holes in the bottom area where one big PS was attached and removed. If that's correct, can someone link me to some PS's that would be suitable? Or some keywords I need for the type of PS?

It's unfortunate that there doesn't seem to be any manufacturer info on the front of the distributions boards so I can go lookup a manual--perhaps there is on the back, so I plan on removing one tomorrow to see.

Hints on wiring would also be greatly appreciated!

Best,
lee

Well, whoever the cab builder was, they did you a bit of disservice by not color-coding the +12V and -12V rail feeders. Hopefully there's indications marked on the backside of those distros (which, I should note, aren't too shabby...they've got filtering, for one thing), otherwise you'll have to figure out their manufacturer and then chase down the board info.

Once you figure out the two 12V rail polarities, I'd strongly recommend yanking the RED wiring for one of those rails and changing it out for some other color to avoid this issue in the future. But as for P/Ss that'll work here, I'd suggest going with this: https://www.newark.com/solahd/sld-12-3434-12t/power-supply-linear-12v-40-8w/dp/93K6589 Yes, it's expensive when compared to switching P/S units, but with a LINEAR supply like this, issues with the P/S leaking crud onto your DC rails become a non-issue. It's worth noting that Synthesizers.com's in-case supplies are also linear, as well as some other makers; even my Kevin Lightner-built Digisound has a honkin' big linear supply in it...and if Kevin Lightner signed off on it, it MUST be the right thing to use!

Oh...and you get 3.4A per 12V rail. Now THAT'S a beefy supply!

Thanks, Lugia! Can I ask you some stupid questions?

Thanks for the PS recommendation. Just ordered it :-)

What would I replace the red wire with? I would assume that the the red and black are either 12v or -12v--and I do have a problem knowing which is which.

Also, dumber question, I presume you're talking about the red wires going to the distro boards? And not the inputs from the power switch that attach to the PS?

I pulled up one of the boards and....amazingly...no writing whatsoever!

https://imgur.com/a/GDQFMT6

Wow...that's super-annoying! You'd think there'd be some indication of connections/polarity on those.

What you've got with the supply wiring is that the builder used red for BOTH "hot" legs and the black wire should be the common ground. Very dumb...because -12V isn't at all the same as +12V. What I would suggest is this:

Grab your multimeter, first off. If you don't have one, get one...these sorts of issues are precisely why EVERYONE doing electronic music needs one of these on hand. So, what you need to do is to check the pin header continuity, since these are invariably the same on ALL distros. So, start here: http://www.doepfer.de/home_e.htm and go to "Technical Details A-100" where you'll find the pin-out diagrams for the 16-pin standard Eurorack power/bus connection.

Next, check continuity. Put one probe onto the -12V rail pins, then see which of the two red wires it corresponds to. Once you know that, the same pin-out will apply across ALL of the distros. And you'll also know which wires need to be changed out to a different color...I suggest something that you can tell at a glance, such as white. Keep the +12V as red. And yeah...the supply lines from the AC switch shouldn't be changed, as there shouldn't be any DC polarity issues until AFTER the P/S unit.

As for that linear DC honker...that thing has enough current capacity that you'd have to really work at trying to overload it. And like I noted, when the P/S is running way under-spec, it runs cooler, and cooler means better operating conditions for it and most everything else. The stability on it should be rock-solid!

Hi Lugia,

Sorry to take so long to reply--I was literally hospitalized. I'm doing better now :-)

I can't seem to find the info on that page you linked :-/ I searched in page for that description, and for every instance of "A-100" and couldn't find a pinout. And I'm not quite certain what you're telling me to check continuity on, so I probably need to see that lol.

But I'll tell you what...it's kinda maddening how there doesn't seem to be any documentation on how to do this stuff on the internet. I checked out a number of sites selling the power distribution boards, and they document everything but how it needs to connect to a power supply, for example. I'm sure the info is out there, but da*med if i can find it. If you've got any links to some general info about how this works I'd be grateful!

For example, I've got a total of 10 blade connectors hanging loose--I'm guessing the daisy chaining couldn't quite deliver power to all 4 boards directly, because one of them has the blade connectors coming from it. Could you double up on a few of them onto that power supply you linked to, for example?

And so I immediately find this thread: https://www.muffwiggler.com/forum/viewtopic.php?t=53338

which has this diagram, which seems to indicate the daisy chain configuration is less than ideal in any case lol:

https://www.muffwiggler.com/forum/userpix/1060_power_distro_1.gif

but man it would be swell to even see a picture of how someone has wired a similar case.