all PCB stompbox (NO WIRES)

[FIŠ]

So, had this idea for a while as I HATE messy wiring, I hate wires in general so made this design :


So as you can see this is general kinda board with mount-on jacks and 3PDT switch (pre-wired for true bypass), rest of the board is schematic components (duh) and I am still working on fitting  pots and LED onto it so there will be not a single wire   (maybe a jumper across the 3PDT as it seems really tight)

Tell me what you think and, if someone has done the same, your experiences

PS. have done precise measurements so this fits all "EHX nano" type of enclosures, made via "ExpressPCB" so i will share if interest is shown

[Pollinator95]

I feel like a broken record, but wouldn't the jacks and switch put quite a bit of strain on the PCB?

[Earthscum]

I've done 1 and the problem comes in with getting the jacks in. You are relying on the PCB and solder to hold the legs. If you crank the nut down, it puts a lot of tension on the legs/PCB/traces. Overcome this by soldering after you install the jacks, but then you will require unsoldering one of the jacks to get the board out to service the unit. Other than that, I loved not running wires.

My suggestion would be to split the board so that the stomp/in jack are on one corner, and one jack and the pot are on the main board. I've been contemplating this one for a while, and have tried a couple pseudo-tests to see if you could stuff and un-stuff it out of a box, and so far it looks like it could work. I'll hit a graphic really quick to show you what I mean, unless someone else pops in with an "it's been done" first, lol.

[Earthscum]

Well, I remember the problem... the idea works for offset jacks, unless you can route boards apart.

Here's the board I made:


I suppose if you get everything sitting just right, you could do slots in the bottom for the jacks to slide up in and lock down on.

[FIŠ]

Hmmm I am not sure i follow you... what tension? The jacks and switch... it is all mounted and screwed onto the chasis and they hold the PCB "floating" in the air, it is all measured to a mm precision so it fits like a glove and there is no force on the solder joints

[FIŠ]

I've done 1 and the problem comes in with getting the jacks in. You are relying on the PCB and solder to hold the legs. If you crank the nut down, it puts a lot of tension on the legs/PCB/traces. Overcome this by soldering after you install the jacks, but then you will require unsoldering one of the jacks to get the board out to service the unit. Other than that, I loved not running wires.

My suggestion would be to split the board so that the stomp/in jack are on one corner, and one jack and the pot are on the main board. I've been contemplating this one for a while, and have tried a couple pseudo-tests to see if you could stuff and un-stuff it out of a box, and so far it looks like it could work. I'll hit a graphic really quick to show you what I mean, unless someone else pops in with an "it's been done" first, lol.

Check this out:


Just file the holes to the edges of a chasis, problem solved

[R.G.]

Hmmm I am not sure i follow you... what tension? The jacks and switch... it is all mounted and screwed onto the chasis and they hold the PCB "floating" in the air, it is all measured to a mm precision so it fits like a glove and there is no force on the solder joints

Aye, there's the rub. 1mm is not very precise where mechanical items are concerned at all.

A mechanical engineer friend of mine gave me some valuable lessons in mounting electronics parts. His advice was this: never, never, never, ever secure electronics to a chassis on more than one plane without a forgiving link to let things move around. In your example, you have fixed electronic parts to three different planes, and held them in place by solder. This **might** work if the soldering holes in the PCB were really big, maybe 1.5-2mm bigger than the leads that go in them and then the parts were soldered on after the PCB was in place and the parts firmly attached to the chassis. That would let the parts self-locate to much, much less than a mm.

If you don't do that (and do it every time you remove the jacks, switch, and PCB) then the nuts that hold the switch and jacks on the chassis will force the PCB to flex that millimeter that it's imprecise. A threaded nut can do several hundred pounds / 1000+N of force. That *will* flex the PCB, and the PCB is very elastic. It happily transfers the force to the solder joints. If the nuts are perfectly aligned, the thermal expansion of the case will put enough force on the controls to introduce flex.

Solder is not very strong. A force of 2300kPa/0.333 PSI will cause it to creep 0.01% *per day*. The PCB patiently holds the force on it till it creeps and fails under tension. Ask an amp tech about how they like PCB mounted potentiometers, switches and jacks.

You're OK if you tie them all to one plane and pay some attention to spacing them all the same. This has a *lower* cracking/failure rate than multiple mounting planes.

Wires do some things very well. Not transferring flex is one of them.

Not that all-PCB stuff can't be done. A lot of it is. It's just failure prone, and people who design for reliability or people who have to fix things that break think it's a bad practice as far as reliability.

[FIŠ]

Hmmm I am not sure i follow you... what tension? The jacks and switch... it is all mounted and screwed onto the chasis and they hold the PCB "floating" in the air, it is all measured to a mm precision so it fits like a glove and there is no force on the solder joints

Aye, there's the rub. 1mm is not very precise where mechanical items are concerned at all.

A mechanical engineer friend of mine gave me some valuable lessons in mounting electronics parts. His advice was this: never, never, never, ever secure electronics to a chassis on more than one plane without a forgiving link to let things move around. In your example, you have fixed electronic parts to three different planes, and held them in place by solder. This **might** work if the soldering holes in the PCB were really big, maybe 1.5-2mm bigger than the leads that go in them and then the parts were soldered on after the PCB was in place and the parts firmly attached to the chassis. That would let the parts self-locate to much, much less than a mm.

If you don't do that (and do it every time you remove the jacks, switch, and PCB) then the nuts that hold the switch and jacks on the chassis will force the PCB to flex that millimeter that it's imprecise. A threaded nut can do several hundred pounds / 1000+N of force. That *will* flex the PCB, and the PCB is very elastic. It happily transfers the force to the solder joints. If the nuts are perfectly aligned, the thermal expansion of the case will put enough force on the controls to introduce flex.

Solder is not very strong. A force of 2300kPa/0.333 PSI will cause it to creep 0.01% *per day*. The PCB patiently holds the force on it till it creeps and fails under tension. Ask an amp tech about how they like PCB mounted potentiometers, switches and jacks.

You're OK if you tie them all to one plane and pay some attention to spacing them all the same. This has a *lower* cracking/failure rate than multiple mounting planes.

Wires do some things very well. Not transferring flex is one of them.

Not that all-PCB stuff can't be done. A lot of it is. It's just failure prone, and people who design for reliability or people who have to fix things that break think it's a bad practice as far as reliability.

All of this makes a lot of sense, but i really wouldn't be concerned about  most of the stuff you wrote.
Jacks are made out of "soft" plastic, also PCB is exact dimensions to almost be slightly "pushed" into the chasis (chasis sides are somewhat narrow as you go in more deeper) so it kinda stucks, all that support from 2 sides of a PCB itself, plastic jacks firmly mounted... I wouldn't be concerned, I will make it in any case so we will see, it Is not a complicated project (DOD 250)
Anyway, thank you for your reply, didn't even remember things like thermal expansion.

[R.G.]

Good luck with it. Let us know how it works out. Not all of them fail.

[Earthscum]

...didn't even remember things like thermal expansion.

Lol... me neither. I think of mechanical failure, i.e. caving the box in... which made me think of something else concerning stomps being PCB mounted. If you get someone who eventually starts caving in the top (I'm sure you know where this is headed, lol)... direct mechanical link to the PCB.

That is one that really came to mind for me when I had to pull and re-fit the board on my project. The nut on the stomp had moved, and I had to kind of re-align everything, which led to just tightening everything and retouching the solder joints at the jacks and (SPDT) stomp to relax everything back into place. I'm starting to think seriously about pulling at least the jacks off the board.

Consider if you run Switch and Pots on-board, you're good for some flex, within reason. You can find a common notch area for the board to clear for open-frame jacks. Gives you some possible extra trace-routing area, as well. Only 5 slack jumpers to strategic positions on the board, 4 if you want to try the ground-thru-chassis game, and 3 if you want to add in "always on, no battery needed" on top.   Plus, your LED is still hard-mounted.

this was my first try using CD4013 switching... not disappointed, so far. 40106 from a SPDT (L) switch to the 4013, no buffers, just an ugly sounding distortion in between, lol. No clicks, either.

[R O Tiree]

3PDT switches are pretty robust and I have mounted them directly to the PCB for a long time. I only ever had one pedal returned for a busted switch. It rapidly became apparent that the guy had tried to dismantle the pedal to see what I'd done... The solder joints were rock-solid. He'd actually broken the switch body!

Moving on, you can get pots with long connectors that you can solder directly into your board. Have a look at Build Your Own Clone board layouts for ideas. The connectors are quite flexible and can therefore accept a certain amount of bending if your holes aren't quite in the right places. We're talking a tolerance of maybe a couple of millimetres, here. The downside is that you have to get all your pot connections to specific places on the PCB, which can be a pain. This will probably mean jumpers or double-sided boards. Alternatively, one often ends up with large gaps in between components so that you can have room on the trace side to run tracks to your pots, which will be a pain if you're trying to cram a complex circuit into a tiny box. Personally, I use triple-twisted wires in 3 different colours. The 3 different colours (a) help identify which hole in the PCB goes to which lug of the pot and (b) look really smart twisted up like that. One occasionally sees claims about reducing interference using twisted wires... are three 2-inch wires really going to pick up any meaningful interference at the voltage and signal levels we're talking about, here? Given all those closely-spaced parallel copper traces all over the board? Well, if it helps at all, then I win. If it doesn't, it still looks smart and helps keep my head straight, so I haven't lost. Still, if you mount the switch and the pots directly to the board, you still only have one plane of attachment, like R.G. and Earthscum have said.

And so onwards to jack sockets. These have the potential to introduce by far the greatest stresses into the PCB and R.G. has given you some numbers to hang your hat on. By design, they're meant to hold jack plugs in quite firmly, so they make a solid connection. Every time you plug in or out, you're almost certainly going to do it slightly "off-centre" which can induce high bending stresses in the PCB. Cutting a slot in the side of your case for ease of assembly makes it even more likely. The most likely point of failure will be the copper traces adjacent to the socket pads. Alternatively, for example, stomp on the jack plug instead of the switch and you could pop some of the socket tags right out of the board... been there, had that when some drunken **** trod on the back of my multi-FX at an open mic night.

So, why do you see this done on the majority of commercial FX? Money, plain and simple. If you can program a robot to place a component and then wave solder it automatically, then you save money. Hand-wiring is very time-consuming and therefore more costly. It's much less failure-prone, though. Does that matter to accountants? It appears not.

[Earthscum]

To back up Mike's experience, I have a Boss ME that has had the jacks stomped on too many times. I swapped the failed "IN/MONO" with the "IN/STEREO L (or R?)". It has since failed as well. Believe it or not, though, the failure is in the jack itself. Apparently the constant flexing has work-hardened and snapped the tip leg to the PCB, while the PCB is holding up nicely.

[FIŠ]

I see, well I wouldnt worry about space because I will be making simple projects this way.
As far as stress on the pcb is concerned, I thought of something today. What if you make strong mechanical connection between two jacks, as shown on the pic below:


Would that help a great deal? If it doesnt work i will simply cut into the PCB  shapes of inpput/output jacks and connect them with a wire, rest will remain mounted on potenciometers and 3PDT

[R O Tiree]

Think how strong it would have to be to resist half the weight of a 90kg person... 45kg force vs plastic body jack. Which one wins? If the only thing it's attached to is the case, then the only thing that breaks is the socket (easy and cheap to replace). The more you try to beef this up, the more force you will transmit to other parts, so repairs will end up more costly.

I use Lumberg jack sockets. They occupy a smaller volume inside the box than Switchcraft sockets, they're cheaper and they seem to be just as strong.

[FIŠ]

Think how strong it would have to be to resist half the weight of a 90kg person... 45kg force vs plastic body jack. Which one wins? If the only thing it's attached to is the case, then the only thing that breaks is the socket (easy and cheap to replace). The more you try to beef this up, the more force you will transmit to other parts, so repairs will end up more costly.

I use Lumberg jack sockets. They occupy a smaller volume inside the box than Switchcraft sockets, they're cheaper and they seem to be just as strong.

I see, ok will heep you updated, ran out of ferichloride so ill start my work 2moro, or the day after

[Paul Marossy]

MXR uses all PCB mounted components on their products like the DynaComp for example. I don't see a high failure rate on those. I think it depends on how well you design it and how close of a manufacturing tolerance you can hold. As a DIY, it would be a lot more difficult to get it perfect.