PCB mounted Pots Pro's & Con's?

[BillyJ]

And what about jacks too?
I am asking because I have just about had it with wires.
Maybe someone knows some handy techniques or tools to make dealing with wires easier?
I use a third hand to hold the board and the wires with the other clip.
Is there an easier or better way?
A pot with wire is six joints but one on a board is three.
What am I missing?
Thanks

[Nasse]

I remember Pete Cornish, a famous custom stompbox builder whose customers are most famous rock stars, said in an interwiev in music magazine that he prefers construction techniques that make strongest possible end result. If someone is stomping on your pots and jacks or pulls a cable accidently that may give your pcb failure. But this kind of tech is used in commercial products and rackmount effects.

[The Tone God]

Using PCB mounted pots do cut down on the number of solder connection you have to make but now that you are attached directly to the PCB. Any shock that the pots get hit with will transfer to the PCB. If you haven't noticed the copper on a circuit is not attached very strongly. Ever pulled a copper trace from the board soldering ? Imagine how easy it will be for one stomp on a pot to do the samething.

One of the things that make building/designing pedals so hard is dealing the physical abuse the pedal will take. Most electronic componets are designed to be used under "normal" load conditions i.e. Turning a knob by hand on a panel. They are not designed to take the physical stress of being stepped on.

With that said you can use PCB mounted pots but you have to make sure you proper means to handle stresses and load. One example is to use pots that have threading for a nut so you can mechnically attach them to the panel like normal pots.

Another issue is your board design. You have to make sure that the pots will line up perfectly with the holes on the panel. If your off you either have to make changes and etch a new board or break out the file/larger drill bit to make corrections to the panel which can be ugly and damage the box in general. Having pots with flexable wiring allows for some tolerence.

Your board will also have be more aware of the third dimension which most people don't worry too much about when designing boards. You can usually play with the board height inside a box when everything is connected using wires. When you attach PCB pots you are then mounting the board to a fixed height. You have to take into account all the other compents not to hit the board at that height. i.e. Jacks, switches, battery, etc.

You have to take the time to address all of these and other issues to sucessfully use PCB pots. This takes ALOT of extra design time which you may not be interested in doing. Most builders get away without having to deal with some of these issues by using wired, not mechaniclly PCB attached, parts. If your serious you might want to look at CADing you effects to deal with some of these issues.

Here is one of things I do to help when wiring parts. I made plate that attaches to the front lip of my work bench. It has various holes drilled in it to fit different parts. Jackes, plugs, switches, etc. It also has holes for different size pots making use of the locating tab which I break off later. I can either bolt the parts to the plate or if I'm in a lazy mood just let it sit in the plate while I solder the connections. If you don't use too many different part layouts you can make a jig that you mount all the parts to and wire it up on that then move it into the box.

Just a few thoughts.

Andrew

[gez]

Does anyone know where to get connectors which would slip onto the pins of a PCB mount pot?  They could be soldered to wires and then just pushed on to the pins, which would be a lot easier.  You see this all the time with speakers, why not pots?

I ordered some 'minature' spade connectors a few months ago but they were miles too big...bugger!

[drew]

I have to admit... I cracked open my Fuzz Factory to have a look, and was inspired by the design. Using a certain type of PCB-mounted pots and a small enough board, you can hold the board in place and have the PCBS wired to the board and mount the PCBs all in one place... and careful placement of the jacks/stomp switch/board means you can perfectly wedge a battery in there too! I am still running through my scads of solder-tab pots but when I get thru I'm gonna investigate getting some of those 9mm Alpha PCB-mount pots.... Dunno if I can get them for eighty-ish cents apiece, but just like using slightly nicer jacks, it'll be worth the money.

[BillyJ]

Andrew that God thing may be tounge in cheek but you are an angel none the less.
I am going to make myself a plate like yours as soon as I can maybe today.
That is a great idea and a thoughtful post on the whole subject. Thank you kindly I knew there was more to it than I thought.
I thinkif the layout is easy enough to meddle with to get the pot mounted up fairly easy I might try it with fixing them mechanivcaly to the box like you mentioned.
As a side I remember you talking about a jig for drilling your boxes.
I have a real hard time doing this task. I have tried the paper template but have less luck with that then a gross method I have devised.
ANy chance you have some ideas about making one?
Maybe article worthy? Not sure anyone else needs help in this area but my boxes take forever to get done.
Well in any event thank you for the excellent input!

[Jered]

If you have access to a small box Rat pedal, open it and you will see an excellent example of pots and stompswitch mounted to the PCB without compromising its durability. The jacks are not mounted on the PCB.
  Jered

[Joep]

Commercial builder use PCB mounted pot/jacks, because it reduces assembly time dramatically. But there a some drawbacks to this technique as Andrew pointed out.

I resoldered a lot of jack connections of commercial effect. Jack connections are often the most abused.

Joep

[The Tone God]

Andrew that God thing may be tounge in cheek but you are an angel none the less.

Thanks alot. Now if only The Spelling & Grammer God would stop ducking my calls I could actually make sense more often. :oops:

I am going to make myself a plate like yours as soon as I can maybe today.
That is a great idea and a thoughtful post on the whole subject. Thank you kindly I knew there was more to it than I thought.

I learned some of this the hard way. I think thats why we're here, to share those experiences. Let us know how the plate turns out.

I think if the layout is easy enough to meddle with to get the pot mounted up fairly easy I might try it with fixing them mechanivcaly to the box like you mentioned.

Give it a try. If it works let us know what you did.

As a side I remember you talking about a jig for drilling your boxes. I have a real hard time doing this task. I have tried the paper template but have less luck with that then a gross method I have devised. ANy chance you have some ideas about making one? Maybe article worthy? Not sure anyone else needs help in this area but my boxes take forever to get done.

Never thought about that. I'll put it on my list of articles to write. I'm sure some other people would be interested as well. Keep an eye out.

Andrew

[jplaudio]

And what about jacks too?
I am asking because I have just about had it with wires.
Maybe someone knows some handy techniques or tools to make dealing with wires easier?
I use a third hand to hold the board and the wires with the other clip.
Is there an easier or better way?
A pot with wire is six joints but one on a board is three.
What am I missing?
Thanks

here's an idea to make dealing with wires easier:
http://www.geofex.com/FX_images/solder_block.gif

jl