Hello and welcome back! Today we are going to pick up where we left off with our Tweed Champ Style Amp Kit build. Last time, we mounted all of our front and rear plate components (potentiometer, tube sockets, jacks, etc.), mounted our transformers, and made a few solder connections.
This time, we will be turning our focus towards our eyelet board. We will get it populated with the proper small components, add leads and traces to it, mount it, and wire everything up! This may seem like a lot of work for one installment, but it’s actually really simple with the 5F1 circuit and in all honesty, it’s my favorite part of any amp build!
First, let’s locate our eyelet board. You should have one board full of eyelets, and another blank board. This blank board is called the backer board, and it will eventually be situated between our eyelet board and the top panel of our chassis to prevent our components from making connections with the metal chassis. We are going to prepare our eyelet boards in three steps:
Populate board with resistors and capacitors
Create all wire traces on the back side of the eyelet board
Attach all wire leads coming from the eyelet board and going out to other components
Right now, following our wiring diagrams, let’s locate each component from left to right and add it to our eyelet board. I’ll meet you back here in just a few!
Notes : Polarized capacitors (those having a negative and positive end) need to be oriented exactly as they are shown on your wiring diagram so pay special attention to these. Use needle-nose pliers to make hooks on the ends of your component leads -- this will keep the components in place as we move forward. If a capacitor and resistor are to occupy the same set of eyelets, it is easiest to twist the resistor leads around the capacitor leads and solder them together later.
Once the board is stuffed with caps and resistors, it should be looking like Image 1A below.
You’ll notice on the far right of my board, I have already attached a yellow lead wire to the eyelet on one end of the resistor. The reason I did this is because the leads on my 1.5k resistor weren’t quite long enough to sit securely in the eyelet. So as a solution, since there was only the one lead wire coming out of the eyelet (this can be confirmed via the wiring diagram), I went ahead and cut the lead wire to length and soldered it in. This may not be necessary in your case, but if it is, this is a good work around.
Now we can move on to hooking in our trace wires. These are denoted on your wiring diagram as semi-transparent, dotted green lines. It appears there are only two actual trace connections on this circuit, so locate them on your diagram and attach these wires to the back of the board (Image 2A).
Okay now we are ready to attach all of our yellow and green lead wires. To approximate the length of lead you’ll need for each, you can use the wiring diagram as a reference, or even hold the fiberboard over the chassis to visualize. The fact is, with a small amp like this, you won’t need much lead -- perhaps 2-3 inches on each eyelet just to be safe. Let’s all follow along with our diagram and get those leads hooked in…
Alright, our leads are in place and now we need to just go through and solder each eyelet hole. Before we do that, it’s always best to double-check (using the wiring diagram) that we have all of our leads and traces in the right places. Once we are confident, we will go through and solder every hole and then trim off the excess lead material…
After everything on the board has been soldered and all the excess lead wire has been clipped, you should be looking something like Image 3A below.
Before we can move on to mounting the board into the chassis, we still need to run a couple of leads which do not require solder at this time. Notice on your wiring diagram the twisted black and white wires on the left side of the board as well as a yellow wire running from the potentiometer, through the center of the board and out to the 12AX7. These need to run between the eyelet board and the backer board. Go ahead and get those threaded through and then we will move on to mounting the board.
We are now ready to mount the eyelet board into the chassis. To do this, let’s first locate the two pre-drilled mounting holes in our chassis (Image 4A below).
Now we can identify a good place to drill these holes in our fiberboard by holding the board up to the mounting holes in the chassis. We should be trying to find a mounting orientation between large components to reduce the risk of hurting something on the board. I’m going to try to get my mounting holes in the areas indicated in Image 5A below.
Once you have decided where you’d like your mounting holes to go, continue holding the eyelet board up to the chassis and mark the chassis with a sharpie where it meets the left edge of your eyelet board (Image 6A).
Then, we will lay our backer board in the chassis, flat against the top panel of the chassis using the mark we made as a reference (Image 7A).
Next, holding your backer board firmly down against the top panel of the chassis, flip the chassis on its side and use your sharpie to mark the backer board through the mounting holes in the chassis…
Now that our backer board is marked, we can drill ⅛” holes in the backboard where we marked. Once our holes are drilled, we need to hold the backer board up to the eyelet board, and use our sharpie to mark the eyelet board through the holes in the backer board (Image 8A).
Next, you guessed it, it’s time to drill those holes we just marked through our eyelet board. In doing so, let’s be mindful of our large components on the other side…
Now it’s time to fasten everything down. Use the remaining 6-32 nuts and screws to do this. The screws will go down through the eyelet board, then through the backer board, and out through the top panel of the chassis. You’ll fasten the nuts from the outside of the chassis. When you’re finished, you’ll have something like Image 9A below…
Okay we have reached our final job for the day, which is to wire up the rest of the circuit...no big deal, right? Unfortunately, we don’t have time to go over every step of this process in today’s tutorial so it is extremely important to have your wiring diagram and your step-by-step build manual in front of you. These documents are very thorough and should guide you to today’s stopping point. Let’s all take some time with our documents and our amp, make the remaining solder connections, and meet back here at Image 10A when we are finished…
Okay folks -- we should be looking something like Image 10A above. Maybe your build is tidier or maybe it’s a little messier. The most important thing is that we’ve completed a HUGE leg on our Champ Kit journey. Make sure you clip any excess leads sticking out of your solder points, lest these little buggers accidentally make contact with something else in the circuit and we spend hours hunting down the problem. If you have an air compressor on hand, it’s also a good idea to blow some air in your chassis to remove any tiny bits that may have fallen into the depths below it all.
We are going to break for the day, so please make sure you join us next time when we are testing out the circuit in a number of ways, wiring up our speaker harness, installing our amp into our cabinet, and ROCKING IT OUT! In the meantime, you can always cross-check your connections once again using your wiring diagram. We look forward to seeing you again soon!