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Step 5Drill board mounting holes, populate and solder board
I have to apologize here for the lack of photos. I thought I was doing a really good job of taking pictures as I went, but apparently there were several rather significant lapses. Before I populated the board, I chose some locations for mounting holes and drilled them. Obviously I avoided areas with traces, but I wasn't too terribly careful because I planned to use nylon washers for electrical isolation. The locations shown worked out great for me, with the exception of the one shown in the top right of the back of the board. The line select switch takes up that space. Even so, there doesn't appear to be any wobble when you plug or unplug into that jack.
After drilling the holes, I epoxied some nylon washers to the bottom side of the board. Not only do these add the height I need to keep the leads from touching the case, they keep the nuts from contacting the traces. I don't remember the exact size I got; it'll vary depending upon the screw you use. I used M3 screws, 1/4" I think. Be careful not to get epoxy in the hole. I smeared a very thin amount of epoxy around the holes, pressed the washer flat to the board, and then placed a fillet of epoxy around the rim of the washer using a syringe. Be sure to get the 30 minute epoxy and not the 5 minute stuff. Once everything's situated, you can cure the epoxy faster if you apply heat. Just set the board on a heating pad and place a cardboard box, like a shoe box, over it. You could use super glue here, but I wouldn't recommend it because once you put the washer down, that's it. You can't move it around if you didn't get it perfect.
Now might be a good time to figure out where to place your mounting holes in the Altoids tin. I wish I'd thought of doing it at this step when I built mine. Place a washer on one of the mounting screws, place it through the hole in the top of the board, and screw on a nut. You should have screw, washer, board, nylon washer, nut. If the screw pokes out through the bottom of the nut, you either need another washer between the screw and the board, or you need a shorter screw. Repeat for all of the other mounting holes. Now place the PCB on top of three 3x5 cards beside the tin. The 3x5 cards give a reasonable approximation of the thickness of the tin's bottom. With the nuts resting on the cards, the board's height should be very close to where it will be when mounted. Mark a line where it contacts the side of the tin. If you used the stereo jacks I suggested in the parts list, you can view the datasheet and see that the plug is 0.236" or 6mm in diameter. So the center of your mounting hole needs to be 0.118" or 3mm above the board line. You can either measure it, preferably with a pair of calipers, or you can eyeball it. I chose the latter method, so I can heartily attest to the fact that it sucks.
Make sure that the hole aligns with the center of the silkscreened jacks horizontally and mark its location. Sharpies work well. You will, of course, need to make certain that the board is aligned with its eventual position inside the tin. Try to be as accurate as possible here, but don't break out the micrometer. Later we'll discover that we have to drill the holes a bit oversized anyway, so there'll be some built-in slop.
Using some fairly rough (320-grit?) sandpaper, scuff the inside of the tin's bottom. Clean the tin using alcohol. Unscrew the screws and place the board into the tin. The nylon washers will be resting on the bottom of the tin. Using a Sharpie, mark the center of each hole, then trace around the inside of the hole.
Now you need to place your parts. Again, I didn't get a shot of the unmounted board with the parts placed. The best I've got is with the board mounted in the tin. There are a few parts with polarity here; IC1 and IC2, C5-C7, D1 and LED1. The electrolytics have a stripe running down one side with a "-" symbol. The polarity is marked on the silkscreen with a "+" symbol; obviously the negative side of the capacitor goes opposite this. If you didn't do the silkscreen or it isn't legible, just refer to the silkscreen gif from step 3. The silkscreen has been mirrored to allow for toner transfer, so flip it horizontally in your favorite image editor. IC1 has a notch on one side; align that with the notch on the silkscreen. IC2 should be mounted with the leads bent so that the metal tab along the back is flat on the board. D1 has a black line (assuming you've got a standard red glass diode; if you've got a larger black plastic diode, it'll be a white or silver line) around one end; align that with the black line on the silkscreen. LED1 might be tricky. There should be a raised rim around the base. One side should be flat. Hold the LED so that the flat side is aligned with the flat side on the silkscreen. If the leads are aligned with the holes, you're in luck. Otherwise, look into the LED. There should be two metallic pieces discernible. One should be vaguely triangular. That one should be oriented towards the flat side on the silkscreen. Note that you'll want to protect the LED's leads from shorting somehow. I stripped the insulation off of some wire and placed it on the LED leads. Very small diameter heat shrink tubing will also work. In a pinch, electrical tape will do as well.
The resistors and ceramic caps can be oriented either way. Clip the leads short, and bend them along their traces on the back side. If you view the pic of the back of the board at full size, you can just make out the bent leads. Be careful not to bridge any leads. Make sure before you solder that the audio jacks are flush to the board. If they're raised at all, they'll be much less sturdy as you're plugging into them. Plus, they'll be a pain to drill mounting holes for. Solder away. Flux is your friend. Until it's time to clean the board, when you'll start to hate it with a passion.
You can see I mounted my switches to long wires. I laid out the wires to the power switch to see how long I needed them, as I didn't want any excess interfering with the battery. The line selection switch I simply guesstimated how much I would need. As I said, I took these switches from a playstation controller. They're actually both SPDT switches, but I'm only using one side for the power switch. I left them on the bit of PCB they came on, as it makes a handy mounting platform. Actually, it occurred to me that it would make a handy mounting platform just after I finished removing them both from the PCB, so I got to solder them right back on. Amazing, how I always come up with good ideas immediately after finishing the work they would have saved me. Anyway, I epoxied some nuts to the PCB, measured the placement, and drilled some mounting holes in the Altoids tin that don't even remotely match the nut placement. I really need to stop that eyeballing habit.
After drilling the holes, I epoxied some nylon washers to the bottom side of the board. Not only do these add the height I need to keep the leads from touching the case, they keep the nuts from contacting the traces. I don't remember the exact size I got; it'll vary depending upon the screw you use. I used M3 screws, 1/4" I think. Be careful not to get epoxy in the hole. I smeared a very thin amount of epoxy around the holes, pressed the washer flat to the board, and then placed a fillet of epoxy around the rim of the washer using a syringe. Be sure to get the 30 minute epoxy and not the 5 minute stuff. Once everything's situated, you can cure the epoxy faster if you apply heat. Just set the board on a heating pad and place a cardboard box, like a shoe box, over it. You could use super glue here, but I wouldn't recommend it because once you put the washer down, that's it. You can't move it around if you didn't get it perfect.
Now might be a good time to figure out where to place your mounting holes in the Altoids tin. I wish I'd thought of doing it at this step when I built mine. Place a washer on one of the mounting screws, place it through the hole in the top of the board, and screw on a nut. You should have screw, washer, board, nylon washer, nut. If the screw pokes out through the bottom of the nut, you either need another washer between the screw and the board, or you need a shorter screw. Repeat for all of the other mounting holes. Now place the PCB on top of three 3x5 cards beside the tin. The 3x5 cards give a reasonable approximation of the thickness of the tin's bottom. With the nuts resting on the cards, the board's height should be very close to where it will be when mounted. Mark a line where it contacts the side of the tin. If you used the stereo jacks I suggested in the parts list, you can view the datasheet and see that the plug is 0.236" or 6mm in diameter. So the center of your mounting hole needs to be 0.118" or 3mm above the board line. You can either measure it, preferably with a pair of calipers, or you can eyeball it. I chose the latter method, so I can heartily attest to the fact that it sucks.
Make sure that the hole aligns with the center of the silkscreened jacks horizontally and mark its location. Sharpies work well. You will, of course, need to make certain that the board is aligned with its eventual position inside the tin. Try to be as accurate as possible here, but don't break out the micrometer. Later we'll discover that we have to drill the holes a bit oversized anyway, so there'll be some built-in slop.
Using some fairly rough (320-grit?) sandpaper, scuff the inside of the tin's bottom. Clean the tin using alcohol. Unscrew the screws and place the board into the tin. The nylon washers will be resting on the bottom of the tin. Using a Sharpie, mark the center of each hole, then trace around the inside of the hole.
Now you need to place your parts. Again, I didn't get a shot of the unmounted board with the parts placed. The best I've got is with the board mounted in the tin. There are a few parts with polarity here; IC1 and IC2, C5-C7, D1 and LED1. The electrolytics have a stripe running down one side with a "-" symbol. The polarity is marked on the silkscreen with a "+" symbol; obviously the negative side of the capacitor goes opposite this. If you didn't do the silkscreen or it isn't legible, just refer to the silkscreen gif from step 3. The silkscreen has been mirrored to allow for toner transfer, so flip it horizontally in your favorite image editor. IC1 has a notch on one side; align that with the notch on the silkscreen. IC2 should be mounted with the leads bent so that the metal tab along the back is flat on the board. D1 has a black line (assuming you've got a standard red glass diode; if you've got a larger black plastic diode, it'll be a white or silver line) around one end; align that with the black line on the silkscreen. LED1 might be tricky. There should be a raised rim around the base. One side should be flat. Hold the LED so that the flat side is aligned with the flat side on the silkscreen. If the leads are aligned with the holes, you're in luck. Otherwise, look into the LED. There should be two metallic pieces discernible. One should be vaguely triangular. That one should be oriented towards the flat side on the silkscreen. Note that you'll want to protect the LED's leads from shorting somehow. I stripped the insulation off of some wire and placed it on the LED leads. Very small diameter heat shrink tubing will also work. In a pinch, electrical tape will do as well.
The resistors and ceramic caps can be oriented either way. Clip the leads short, and bend them along their traces on the back side. If you view the pic of the back of the board at full size, you can just make out the bent leads. Be careful not to bridge any leads. Make sure before you solder that the audio jacks are flush to the board. If they're raised at all, they'll be much less sturdy as you're plugging into them. Plus, they'll be a pain to drill mounting holes for. Solder away. Flux is your friend. Until it's time to clean the board, when you'll start to hate it with a passion.
You can see I mounted my switches to long wires. I laid out the wires to the power switch to see how long I needed them, as I didn't want any excess interfering with the battery. The line selection switch I simply guesstimated how much I would need. As I said, I took these switches from a playstation controller. They're actually both SPDT switches, but I'm only using one side for the power switch. I left them on the bit of PCB they came on, as it makes a handy mounting platform. Actually, it occurred to me that it would make a handy mounting platform just after I finished removing them both from the PCB, so I got to solder them right back on. Amazing, how I always come up with good ideas immediately after finishing the work they would have saved me. Anyway, I epoxied some nuts to the PCB, measured the placement, and drilled some mounting holes in the Altoids tin that don't even remotely match the nut placement. I really need to stop that eyeballing habit.
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