MIM: Build A Mojotone TS-1 Pedal Kit

Written by
Logan Tabor
Published on
January 19, 2021 12:47:59 PM PST January 19, 2021 12:47:59 PM PSTth, January 19, 2021 12:47:59 PM PST
Over the past couple months we have gone over some simple DIY projects that should get you started working with specific tools and electronic components that we will see quite often in the amp and guitar world.  Now it's time to step it up just a little bit and dive into a Mojotone TS-1 Tube Screamer pedal kit.  Let's get to it!

Step 1 : Tools and Supplies

As always, we want to make sure we have the right tools to do the job, so let's go over a few of the things we'll be using today.  

We definitely need a soldering iron and some solder, so go ahead and plug the iron in and get it nice and warm.  To work with the hardware, we will need screw drivers and nut drivers so I've brought my Rene Martinez 24-piece microtip screwdriver set, as it should cover anything I need it for (See Image 1A).  


Next, we will need some tools to bend resistor leads and cut off the excess lead once soldered into place.  To bend, you could use a set of needle nose pliers, and to cut you could use a set of wire cutters -- I'm feeling adventurous today so I'm only going to be using a pair of wire strippers to do the cutting and bending.  In any case you will need a pair of wire strippers as we are going to be making our own length of wire for a number of connections later on.

Now that we've covered our tools, let's just do a quick check to make sure all the parts are present in our kit.  The kit should have come with a plastic box to organize all the small parts, with a key for identifying all the parts, so just quickly check to make sure every compartment has its proper small part(s).  We should also have (1) PCB, a white powder-coated pedal chassis, a 9v battery, and some wire (See Image 2A for all tools and supplies).  


Step 2 : Installing the Hardware

Since the potentiometers will mount directly to the PCB, we are going to wait to install them until we are stuffing our board.  For now, lets go ahead and mount our input and output jacks, footswitch, and DC power jack.

For our input jack we are going to use the Switchcraft J12B -- and, as usual, the input will be on the right side of the pedal if we are looking at the pedal from the outside.  Remove the nut and washer from the jacks and install them accordingly.  Once hand-tightened, use a nut driver to tighten further, but be careful not to over-tighten (See Image 3A).  Note : Pictures will be taken from the inside of the pedal as we work on it, so be mindful of which side components should occupy. 



When installing the footswitch component, make sure the first nut and the white plastic washer are on the outside of the pedal, but that the lock washer and second nut are on the inside -- also, make sure that the lugs on the footswitch are oriented horizontally once installed.  Once you've installed your hardware components, your pedal should look like the one seen above in Image 3B. 

Step 3 : Stuffing the Board

Now we are ready to start populating our PCB with electronic components.  It is typically good to begin by inserting resistors, as they tend to lay closest to the surface of the PCB.  Resistors are represented on your board as little white rectangles with an alphanumeric value in the middle of them (See Image 4A) -- look at the board and then locate the corresponding value of resistor in your plastic organizer, and begin stuffing (See Image 4B).



I am going to stuff all my resistors and diodes on this first pass.  A good thing to note is that your diodes need to be oriented a certain way, which is indicated on your PCB by a rectangle, with a smaller rectangle inside of it at one end or the other (See Image 5A).  Make sure you line up the corresponding side of the diode with the indicator rectangle on the PCB.  



As you're stuffing your board, think of your PCB in layers so that it becomes easier to work with -- once one layer of components, all of the same "height," are installed you can flip the board, solder them into place (See Image 6A), and move onto the next height layer.


One thing to note while installing capacitors is that non-polarized caps are marked as seen below in Image 7A, with a symbol that looks like two of the letter "T" facing end on end with a capacitor value listed above or below.  When, a cap is marked as non-polarized, the orientation of the positive side of the cap is irrelevant.  However, if a cap is marked on the PCB as seen below in Image 7B, you should be given an indication of where to insert the positive lead on the capacitor -- in this case, the orientation of the positive lead is imperative and should be done accordingly.  



There are a few things along the way that may lend themselves to personal preference; for instance,  I am going to mount my 2 ground terminals onto the bottom side of the board so that I have more room to make connections when the time comes (See Image 8A).  


One final thing to make sure of is to have your potentiometers oriented in such a way that they will line up with the corresponding holes in your chassis, while face up towards the DC power jack (See Image 9A).  


Step 4 : Wiring the Switch

Once we've finished stuffing, soldering, and trimming up our PCB, we can move onto wiring the switch around to the other components -- this is where our wiring diagram is going to be a big help.  But first, let's mount our PCB into the pedal chassis via the nuts and washers from our potentiometers.  Remove the nut and washer from each pot, insert the pots into their respective chassis holes and then re-fasten the washers and nuts on the outside (See Image 10A).  After you've done this, your pedal should look like the one seen below in Image 10B. 


At this point, you will want to pay very close attention to your wiring diagram and perhaps even mark out connections or circle them once they've been made so you know where you are in the scheme of things.  I encourage you to go in whatever order strikes you at this point -- you may find, in the end, that it would have been easier here or there to have changed the order of one or two things, but once it's all said and done this is a learning experience and these "setbacks" are necessary evils.  An important thing to note on your wiring diagram are the small jumper wires (2 to be exact) that connect from one lug to another lug on your switch.  For these, I like to use little bits of lead wire that I have trimmed off of resistors, so if you have any of that left over, it should work just fine.  

So, take your time, follow the diagram and start making connections from the switch out to the other components and we will meet back here when your pedal looks similar to the pedal seen below in Image 11A.


Step 5 : Final Component Wiring

At this point, we are almost all the way home!  We just need to make a few more connections, namely connecting our battery clip into the circuit via the DC power inlet and positive input jack terminal, and connecting our DC jack to the ground terminal on our input jack.  Let's identify these final connections using our wiring diagrams and gently solder everything into place.  When it's done, the inside of the pedal should look something like the pedal below in Image 12A...although, perhaps yours is a cleaner assembly...perhaps it's dirtier!  Who knows, that's the fun!  


Step 6 : Double Checking and Testing

I always like to put my freshly built pedals right next to the wiring diagram and just have a second look, so I strongly recommend doing this.  Once you have double-checked every connection, trimmed any stragglers off of their respective terminals, dropped in the 9v battery, and sealed up the chassis, and added knobs and feet, it will finally be time to plug it in and see what it sounds like.  In the end, you should have a super rockin' tube screamer that looks something like the one below!  Crank it and enjoy!