New revision for the Eurorack Compact Power Bus!

The Compact bus is one of the smallest yet powerful Euro bus in the world. Yes really 🙂 It’s only 10cm long but you can plug 8 modules plus 4 tiles and one Analogue Systems module!

Construction details

The board is really easy to solder. There are, on the bottom side of the board, 3 SMT resistors and 3 SMT capacitors. But don’t be afraid, those are 1206!

1206 SMT devices are big enough to be soldered with standard through-hole equipment. I personally use a cheap soldering iron.

What makes the difference is the thickness of your solder. I recommend 0.5mm solder wire. 0.3mm is better, but consider it only if you plan to do a lot of SMT soldering in the future.

Besides, it can be a great opportunity to experiment your first SMT soldering job. And don’t worry, if you aren’t successful, well, your board will still be fully functional! Only the LEDs might be inoperative.

Step by step assembly

Start by soldering the 6 SMT devices. Apply a small amount of solder on one pad of each component. with fine tweezers, place your component in its designated location, then reflow the solder with your iron while you slightly adjust the alignment of the component over the pads.
If you’re satisfied with the position, you just have to solder the second pad, and voilà!

If you do own an Analogue Systems module, you can solder the 16-pin DIP connector now. If you don’t have such module, skip this step.

Solder the 8 Eurorack connectors. I recommend boxed headers but some will prefer the unboxed ones. It’s your call! Eurorack Connectors are 2×8 pins, 2.54mm pitch.

Next, you can solder the four 3-pin “1U Tiles” connectors. Again, if you don’t use 1U Tiles, then simply skip this step.

I recommend to solder the LEDs now, before the big power input connector. If you flip your board, it will sit flat on your desk. It should be easier to align the LEDs vertically.

Last step is the power input connector. You can use different solutions but the one I use and recommend is the Screw Terminal Block. It allows you to accommodate a lot of different power sources. The pin pitch is 5.08mm.

Power on

The board requires 4 power rails: +12, -12, +5 and 0V (0V is marked “GND” on the board). The +5V rail can be skipped if your modules don’t require it.

If you have some doubts about the difference between the -12V and the 0V, please read my previous post “Ground is Not your Negative Rail“.

When powered on, the LEDs should lit. If not, double check your solders and most important, check the polarities of both LEDs and your rails.

Documentation

• Interactive Component Map