DIY Kit - Wiring the Box
Got the box? That's great!
If your Gecho board also requires some soldering, please follow this guide first.
Drilling holes for wires
If you find it handier to drill from the battery side, it is a good idea to put some thick cardboard between the lid and rest of the box, to not damage the lid. Or do it other way round, and put a cardboard under the box, to not damage the table.
Use battery holder to see how much space will be left, then mark 4 dots where to drill, approximately like this. Exact position does not really matter. Be careful about the orientation, box is upside-down and sliding door opens to the right. Note: if your DIY kit is of "nothing left to solder" kind, you only need 3 holes here.
Remove the holder and drill the holes.
Mount the battery holders. It is important to place double-AA holder on top and single one on bottom, as then the mounting screws will go in between them, and there is no danger to damage holders (e.g. if you use longer screws). You can use glue or double-sided sticky tape, that worked really well for me (it's a lot quicker). If your battery holder has a bump in the middle at bottom side, you might want to use two separate pieces of the tape, so it does not stand out too far.
Wiring to the board
Fit the wires through the holes, be careful about the order. From left to right: single holder red (+), double holder black (-), double holder red (+), single holder black (-). These will effectively become +4.5V, GND and +3V (which joins both holders).
If your kit comes with one triple-AAA battery holder instead, you might want to read this discussion about what's the best way to connect it.
Your double-AA battery holder might be of a reversed version, having positive and negative contacts flipped. In such case, you may want to wire it like this (the single-AA was flipped too, so the pattern of every other battery being placed in opposite direction is not broken):
At the other side, it should be connected to the board like this. You may want to shorten battery holder leads a bit, so they are equal lenght, but not too much, as then it will be harder to solder them.
In case of MIDI installed, you can end up doing something like this.
Finally, center the board, carefully drag the wires back (so they don't stay caught under) and secure the board using two screws provided. It is easy to do with a screwdriver, no need to drill. It may be a good idea to place small pieces of foam under the board, to make sure it sits evenly flat. I am using this kind of foam, it's about 1.5-2mm thick:
Instead of placing the foam under entire board, cut two 1x1.5cm pieces and place them under screws, and a third one - cca 0.7x2cm - under first two rows of LEDs. Elements and THT pins will keep the foam in place. The goal is not to insulate anything but rather to keep board evenly positioned as battery wires may lift it up a bit at their end. However, if you can solder the wiring really flat (or your kit comes with wires pre-soldered), no foam may be necessary.
Be very careful about positioning, as then it won't look too good, and connectors might not match the holes. Ideally, leave the same space around all four sides of the board. Secure one screw first, then re-align and secure another one. And mainly, don't forget to test it before fully securing the screws. Make sure the board is not bent due to uneven pressure from screws - never tighten them fully.
If your DIY kit is of "nothing left to solder" kind, there are wire connectors provided to connect battery holders to the board. Your board comes with 3 pre-soldered wires (so you only need to drill 3 holes).
Word of caution: If you decide to play with this board by powering via USB before mounting, be sure to place a sheet of paper between electronics and pre-soldered wires. Even without isolation not stripped at their ends, the wire may be protruding a bit and there is chance they might accidentally touch some element and damage the board.
In your packet you should receive 3 pairs of connectors and some isolating thermal-shrinking tube.
These allow you to connect two wires without soldering. First, remove few millimetres of isolation from each wire, then place the ends into connector. Subsequently, use a pliers to press the middle part of the connector so it wraps around un-isolated wire. Afterwards, use pliers to wrap the end bit of the connector after isolated part. Finally, cut each tube in half, and fit it over the connectors as shown. There are 3 colours provided so you won't make a mistake later, should you need to disconnect this. Use a heat gun (if you got one), if not, it is also possible to do using lighter or candle (just ask google or youtube).
The third and fourth wire (the positive/red wire from double-AA holder, and negative-black wire from single-AA holder) need to be joined together, they should both fit into a single wire-connector terminal. See this wiring diagram, and please check that the wires on your board are soldered correctly. There is not much danger from reverse polarity, the board has protective diodes - however, connecting 4.5V to VBAT+3V might cause a damage.