Basic Workflow Tips for Building a PedalPCB

[mjd515]

wait so you put the Pots on the other side of the board? ive been putting them on the same side as the resistors and such...welp looks like i gotta reorder.

 

[Barry]

A soldering technique thread would be incredibly helpful. I am yet to build my first Pedal, my PCBs are on their way and I am collecting all the information I can find. On the soldering side, I am planning on getting a Weller WLC100 with a small chisel tip. A Kester 60/40 solder .020"/.50mm, a flux pen, solder wick and some blu-tack. Any and all suggestions are welcome

There are lots of tutorials on you tube

 

[Chuck D. Bones]

wait so you put the Pots on the other side of the board? ive been putting them on the same side as the resistors and such...welp looks like i gotta reorder.

Besides reading the Basic Workflow Tips for Building a PedalPCB, take a stroll thru the Build Reports forum. You'll find dozens of pictures of well-built boards.

Don't feel bad, I mounted a 4PDT toggle on the wrong side of the board (DOH!) once.

 

[chongmagic]

Haven't gotten around to mentioning it but kudos on the write up Jovi! You are indeed very meticulous,. I suggest every beginner read through this as it will help with any issues down the road.

 

[TheSin]

Step 4: Cleaning the PCB and adding potentiometers and switches
The board is populated. In this photo you see that I haven't added the transistors into their sockets yet. They get in the way when soldering the pots and switches so I'll add them later. The same applies for any socketed component, i.e. IC's
fig. 14
View attachment 1373
*Yes, it missing a capacitor. It's optional on this PCB.

But look how dirty it is underneath.
fig. 15
View attachment 1374

Cleaning the PCB
The method I use to clean all the flux residue from the bottom is simple. Isopropyl alcohol, a toothbrush, and paper towel.
fig. 16
View attachment 1375

Lay the towel over the bottom side of the PCB and hold it in place. Saturate the paper towel in isopropyl alcohol and brush for a few seconds. When the towel starts to break down or look "fluxy" move to a dry patch of towel and repeat. Do this three or more times depending on how dirty it was. This towel method keeps the alcohol and residue from running through to the business side of the board. Here it is all clean.
fig. 17
View attachment 1376

Time to add the potentiometers
First, bend the the legs into a "\ | /". Doing this gives the potentiometer some tension when you insert it into the pads on the PCB so it won't fall out. Next, bend your potentiometer legs to about an 80° acute angle. This gives you clearance from the other pot solder pads and the offboard wiring we will do later. Like this...
fig. 18
View attachment 1420

Add flux to the PCB pads and potentiometer legs and insert them into the board. They should stay in the board without falling out.
fig. 19
View attachment 1382

Test Fitting
Drop the board (now with unsoldered pots) into your enclosure. I do this on the outside so I have easy access when soldering. My drill holes are symmetrical so this works. If your holes aren't symmetrical (due to drilling misfires or asymmetrical toggle layout) drop it into the the inside of the enclosure. I then gently hand-tighten the potentiometer nuts until they are just snug. This just temporarily holds everything secure while we get ready to solder.
fig. 20
View attachment 1384

What if you have toggle switches?
If you have toggle switches flux pen the lugs and it's corresponding pads then gently hand tighten them into the enclosure before dropping your board (with unsoldered pots attached) into the holes. Basically, with this technique, everything is anchored to something so that you have a solid base to work from. Like this...
fig. 21
View attachment 1419

Avoiding potential grounding issues
To avoid any possibility of creating a short I lift the PCB up slightly to create a gap between it and the pots. The tension created by previously bending the pot legs holds the PCB secure. Also, in this photo below I insulated the one pot that doesn't have a dust cover with tape for added insurance.
fig. 22
View attachment 1389

Solder the potentiometers and switches
Do a final once over to align and center the board, pots, and switches if needed. There is a bit of wiggle room. I like to solder one leg then move to the next potentiometer or switch, reducing the chance of overheating. Repeat until all legs and switch lugs are done. Unscrew the nuts holding the components down and remove your completed PCB. When the time comes, it will now drop into your enclosure holes with no resistance.
fig. 23
View attachment 1386

Continued below...

I clean my pcb after soldering w 91% alcohol but it leaves a whiteish sticky residue afterwards..do u get that too??

 

[Nostradoomus]

You’ll want to get 99%, that other 9% is water...not what you want anywhere near electronics.

 

[Chuck D. Bones]

99% alcohol won't be 99% any more once you open the bottle. Alcohol is hygroscopic and will absorb H2O like nobody's business when exposed to the atmosphere. I use 91% and it works just fine. If you're getting sticky residue, it's because you are not using enough alcohol. You have to flood the board, scrub it with a toothbrush and then flood it again. If you try to swab the board with alcohol, you're just spreading the flux around.

 

[TheSin]

99% alcohol won't be 99% any more once you open the bottle. Alcohol is hygroscopic and will absorb H2O like nobody's business when exposed to the atmosphere. I use 91% and it works just fine. If you're getting sticky residue, it's because you are not using enough alcohol. You have to flood the board, scrub it with a toothbrush and then flood it again. If you try to swab the board with alcohol, you're just spreading the flux around.

I actually did flood it more than once with a piece of tp and used a toothbrush, but maybe I didn’t do it enough though?? It’s almost like the alcohol is reacting with or stripping the top coat off the pcb.
I built a 2nd pedal right after and didn’t use any flux paste or pen. It came out just fine and works nicely, and I didn’t have to do any cleanup. Im wondering how necessary using flux paste/pen really is? I’m only 6 months into pedal building so Im still learning....

 

[Chuck D. Bones]

I find that flux is helpful, but not always necessary. Most solder has a flux core and that's sufficient.
I find flux most useful in these circumstances:
1) Tinning stranded wire - helps the solder wick up between the strands
2) Soldering to anything with a large thermal mass: pot backshells, circuit board ground plane, the ground lead on jacks that are mounted in the chassis...
3) Soldering to the leads of NOS parts
And of course flux is absolutely necessary when using solder braid.

When I say flood the board, I mean submerge it in a puddle of alcohol. I put 100ml or so in an old pie tin and tilt it to get a deep puddle along one edge. Slosh that around, then scrub, the more sloshing. After that, set the board on edge so the alcohol drains off. I've never had the alcohol react with or strip the solder mask off of a circuit board.

 

[TheSin]

I find that flux is helpful, but not always necessary. Most solder has a flux core and that's sufficient.
I find flux most useful in these circumstances:
1) Tinning stranded wire - helps the solder wick up between the strands
2) Soldering to anything with a large thermal mass: pot backshells, circuit board ground plane, the ground lead on jacks that are mounted in the chassis...
3) Soldering to the leads of NOS parts
And of course flux is absolutely necessary when using solder braid.

When I say flood the board, I mean submerge it in a puddle of alcohol. I put 100ml or so in an old pie tin and tilt it to get a deep puddle along one edge. Slosh that around, then scrub, the more sloshing. After that, set the board on edge so the alcohol drains off. I've never had the alcohol react with or strip the solder mask off of a circuit board.

I’ll give that a shot one of these days....appreciate it!

 

[jubey]

Hello guys and gals.
I am a beginner into soldering pcbs (so keep that in mind ).. Just working on the Spatialist and everything is fine but I came across something that confuses me.
When watching people solder diodes, it seems the orientation of the square and round marked point are different then on the arachnoid pcb (see pic). The marked kathode points towards the circle, but on arachnoid it’s a square... Why is that?
Thanks

 

[joelorigo]

Hi,
Total rookie question about Step 3 - testing components. I was able to quickly find out how to test resistors. But I'm a little confused about the setting on the multimeter for capacitors. And what reading I am looking for. What about diodes? Are they to be tested?

 

[Chuck D. Bones]

Most cheap multimeters don't have a capacitor setting. Get one of these for testing capacitors, inductors, diodes and transistors. It even does resistors! Money well spent.
There are two schools of thought regarding component testing:
A) You can test them before you install them and avoid potential component problems later on.
B) You can power up your pedal and test them that way. If they're all good, no problem. If you have a bad one, we'll see you in the Troubleshooting forum.
I highly recommend Plan A for newbies.

 

[joelorigo]

Does this multimeter have a capacitor setting? It's the one I have

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[Chuck D. Bones]

NO. And don't trust the transistor tester function.

 

[joelorigo]

Ok. Thank you. If I am getting capacitors, diodes & transistors from Guitar Pedal Parts, Small Bear, Digi Key, Mouser, etc. is there any worries that they would be not what they are supposed to be?

 

[Robert]

I don't have any experience with Guitar Pedal Parts, but you can trust Small Bear, Digi Key, and Mouser.

 

[joelorigo]

Super. Thanks guys.

 

[Nostradoomus]

Oh whoa guitarpedalparts is just across the border from me basically...I’ll give em a whirl!

 

[Barry]

It's often the pedal builder that makes the error not always the supplier