ThruBox Build Instructions

Build Instructions, Step 1 – for both options

All components go on one side of the PCB – the side with the part numbers printed on it.

Solder parts into the marked positions; where a part has to go a specific way round there will be markings on the PCB to guide you, and a clear note in the instructions.

We add parts to the board in height order, starting with the shortest parts (this makes the PCB easier to manage and handle during the build).

D3 – small signal diode

Find D3 in the upper-right of the PCB. Diodes have to be inserted the correct way round – so make sure that the black bar at one end of the diode matches the bar on the printed symbol. Set the diode into place, check it, then flip the board over and solder it into place. You can tidy the wires now with a pair of cutters or do them later (I tend to do mine as I go along as it makes the PCB easier to photograph).

R1 – 10K resistor

Next, locate R1 – it’s just to the left of the diode you just soldered. Resistors don’t care which way round you put them but you do have to be sure you’re using the correct value – either check it with a multi-meter or refer to this chart to be sure you have the correct resistor. Then put it in place, flip the board over, solder it, tidy if you want to.

R2 to R12 – 220R resistors

All of the remaining resistors on the board are 220 Ohms; go ahead and put them all in place. You can give yourself extra art points for keeping the colour bands running the same way right across the PCB (but it doesn’t make any difference to the circuit if you don’t do this, so don’t sweat it).

D1 and D2 – rectifier diodes

Again, these diodes have to be inserted the right way around – make sure that the black bar at one end of the diode matches the bar on the printed symbol. Check them again before you solder. These might be a little trickier to solder than the components that you’ve done so far as they soak up quite a lot more heat; if you have an adjustable soldering iron, it’s worth giving yourself an extra few degrees for this part of the job. Wait until these have properly cooled, then, if you’ve not tidied the spare wire away from the back of your PCB yet, do it now – it makes getting at the next couple of components a lot easier.

U2 and U3 – IC sockets

We don’t solder Integrated Circuits (“chips”) directly to the board – the heat would damage them. Instead, we use these IC sockets. Although these don’t really have a “correct” way round, it’s sensible to line up the notch at one end of the component with the notch marked on the PCB silkscreen, as this helps us make sure we put the ICs in the right way later.

Holding these in place whilst turning the PCB over can be tricky – I usually locate the socket in the PCB, put a piece of card over it, then turn the PCB and card over at the same time – this holds the socket in place. Slip the card out from under before you start soldering, though.

Install one at a time and make sure that you don’t miss any pins when soldering.

U1 – voltage regulator

This component takes the incoming voltage of 9 to 12 volts DC and brings it down to a nice, steady 5V. It’s important that it goes in the right way round, but if you take a close look at the photo you’ll see there’s only one way it will actually fit. First thing you’ll need to do, though, is make it bend at the knees.

Hold the component so that the flat, metal “back” is away from you, the black resin “front” facing you. The components legs are wider at the top – about a millimetre below where the wide part of the leg ends, bend the leg 90 degrees away from you. Do this for all three legs – you can use pliers or even just the straight edge of a ruler to do this. You should now find that the legs fit straight into the holes in the PCB and the flat “back” of the component sits flush on the exposed area on the PCB – the holes in the component and PCB should line up, too.

Although it’s not essential to bolt the component to the board, it’s worth doing – if only to help keep it still during soldering. Use an M3 machine screw and nut if you choose to do this.

C2, C3 and C4 – ceramic capacitors

After that last step, this bit is really easy. We only use one value of ceramic capacitor in this project and they can go any way round, so locate C2, C3 and C4 and get them soldered into place.

C1 – electrolytic capacitor

Electrolytic capacitors are polarised – they have a positive and a negative connection and these have to be the right way round. Find C1 on the PCB – you’ll see that one hole has a “+” symbol next to it. This shows that the positive pole of the capacitor should connect here – the other hole is, therefore the negative.

There are two ways to tell which connection is which on an electrolytic capacitor:

The positive lead will be longer than the negative lead

The negative lead will be marked by a white stripe down the side of the body (or “can”) of the capacitor

So, put the long leg of the component into the hole marked “+” – this should mean that the white stripe on the body is on the side that faces your 14-pin IC holder for U2. Push it down snug to the board and solder it into place.

That’s the majority of the components in place – but pay close attention because the instructions diverge a bit now, depending on which option you’re building. If you’re making the cased version of the ThruBox, you can skip ahead to step 3, otherwise carry on with step 2.

Step 2 – embedded option only

This part is for the embedded version of this project only – if you’re building the complete, cased version you can skip to the next step.

J1 to J7 – pin headers

Since you’re going to be embedding your PCB inside another project, a rack case or a custom enclosure, all you’ve got left to do is give it a means of getting connected. Solder a 2-pin header to each of the marked points and you’re done!

You can skip ahead to the power test step now.

Step 3 – cased option only

You’ll need the top panel for this step, so make sure you have it to hand; it’s time to add some power to the PCB.

JK1 – DC inlet

JK1 will only fit one way – note how the pin arrangement is “keyed”. Don’t be tempted to solder it into place immediately, though – we have to ensure it aligns with the top panel correctly before we solder it. The first thing we need to do, therefore, is put the mounting posts in place so that our top panel has something to attach to.

Attach a post into each of the four M3 holes and secure it in place with a nyloc-style nut. Make sure they’re nice and snug but don’t overtighten – you don’t want to crush the PCB.

Now put JK1 in place but, again, don’t solder it yet. Instead fit your top panel in place, using M3 machine screws to locate it onto the tops of the posts. Don’t tighten the screws up beyond finger-tight as you’ll need to remove the panel again in a minute.

Ensure that the DC inlet hole in the panel and the hole in the component align nicely; jiggle JK1 around a bit if you need to. Plugging in a DC plug can be useful here, too – but make sure it’s not connected to mains!

When you’re sure you’ve got it aligned, flip the whole thing over and solder JK1 in place. The holes for the pins are pretty big so be generous with the solder, remembering to heat the pin, the pad and the solder all at the same time to ensure a good connection.

When that’s done and cooled, remove the top panel again and set it aside.

Step 4 – power test

Before we go any further, we’ll just carry out a couple of simple tests to make sure the circuit is going to carry power in the way that we want. We’ll do this before we insert our sensitive ICs into their holders.

With your meter set to detect continuity

Touch one of your meters probes to pin 7 of the U2 socket; touch the other to pin 14. There should be NO continuity between these pins (if there is, take a good look over the back of your PCB and look for shorts between soldered connections. Rectify and try again)

With your meter set to measure voltage

Connect your ThruBox to a power supply, ensuring that the connection polarity is the right way round and your meter will detect and display 5 volts DC.

Touch your meters BLACK probe to pin 7 of the U2 socket; touch the RED probe to pin 14. Your meter should display 5V (or thereabouts; a small variation is acceptable)

Touch your meters BLACK probe to pin 5 of the U3 socket; touch the RED probe to pin 8. Again, your meter should display approximately 5V.

Assuming all is well, disconnect the DC power – it’s time to carry on. If you’re building the embedded version of the ThruBox, skip ahead to step 6 now.

Step 5 – cased option only

It’s time to add the MIDI connectors. To do this neatly, we’ll need the top panel in place so go ahead and put it back on, remembering to only go finger-tight with the machine screws.

Gently drop JK2 into place (you might need to give it a bit of a jiggle or manipulate the pins a little to get it to seat properly). When it’s in place, you should find that the metal rim of the jack sits less than a millimetre proud of the top panel.

We need to flip this over and keep it in place and keep it pushed right into the PCB – we’ve found that using a small coin (a UK penny is perfect) as a “shim” under the flipped-over jack is perfect. Solder one or two pins and then flip it back and check it’s still where you want it to be. De-solder and adjust if necessary, then flip back over and solder the rest of the pins.

Repeat the above for all of the remaining MIDI jacks. When you’re done, you can remove the lid again.

Step 6 – for both options

Insert the ICs U2 and U3 into their sockets. These have to be properly aligned – this is where making sure the sockets were installed correctly pays off.

Rotate the board so that, as you look at it, the notches in the U2 and U3 sockets are at 12 o’clock. In this orientation, pin 1 is at the top left of each socket.

The U2 IC will have a notch in one end. Match this to the notch in the socket, then gently but firmly insert the IC into place. Note that you might need to narrow the splay of the legs a little with some gentle finger pressure first.

The U3 IC will have a solid printed dot in the corner that holds pin 1. Align this with the top left corner of the socket, then gently but firmly insert the IC into place. Again, you might need to adjust the legs of the IC a little first.

If you’re making the cased ThruBox, put the top panel back on. This time you can fully tighten the machine screws. If you have an enclosure to put your finished piece into, move on to step 7. If you don’t – that’s fine, you can move on to testing and using your ThruBox.

If you’re making the embedded ThruBox – you’re pretty much done! Connect your preferred power supply and MIDI connectors to the appropriate pin headers and move on to testing and using your ThruBox.

Step 7 – cased option only

If you’ve bought our recommended enclosure, now is the time to use it! Unpack it and set aside the lid and the screws (you won’t need them – put them in your “bits box”, they’re bound to come in handy for something, one day!)

If you’ve bought self-adhesive feet, fix one in each corner of your enclosure and give them a good press into position. Now turn the box over and place the finished ThruBox assembly into position. Use the four machine screws that came with your panel to secure the whole thing in place.

Alternatively, if you’ve got one of our NiceBottom enclosures, now is the time to unpack it and follow the instructions for putting it to use.

You’re finished! Looks great, doesn’t it?

Testing

Power up your finished ThruBox, connect the MIDI OUT from a MIDI source (such as a keyboard) to the IN connector. Then connect one of the five outputs of the ThruBox to the MIDI IN of a synthesizer, sound module or drum machine. Any MIDI messages that you generate from your source device will be passed along to the output device.

If there are any problems at this stage, go back to your PCB and check for shorts, also ensure that the ICs are correctly oriented.