Reasons for/against circuit integrated with 3PDT PCB?

Started by SmoothAction, September 03, 2013, 02:38:05 PM

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defaced

#80
Quote from: Arcane Analog on September 07, 2013, 09:46:23 AM
Quote from: defaced on September 07, 2013, 08:40:30 AM
Quote from: Arcane Analog on September 05, 2013, 08:28:16 AMBottom line is that Military Spec - which is the standard for a quality build with durability in mind - incorporates wired leads. If PCB mounting was more secure/reliable/durable the US military would have used that technique.
You got the number of the spec you follow?  I'd be interested in looking at that.  
Sorry - direct me to where I said I built to mil-spec and perhaps I can go from there.
Actually, I was just interested in checking out the spec.  I figured since you were claiming that a particular method of construction was Mil-Spec that you'd indeed know what spec it was compliant with. I never assumed your builds were Mil-Spec. 
-Mike

R.G.

Try looking here:
http://www.everyspec.com/MIL-STD/MIL-STD-2000-2999/MIL-STD-2000A_10935/

Sometimes it's hard running down such specs. Last time I found them it was on the public server of the Rome (NY) military base. But "everyspec" seems to have them. They're just hard to filter out.

MIL-STD-2000A seems to the the last version before it was canceled. It's some  4+ Mb. The precursor was 8+Mb. Makes for run reading.

There are more covering printed circuit construction and such, but I didn't find them in a quick search.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

defaced

Thanks, R.G.  That looks like it covers the practices I was interested in. 

Yea, finding military specs can be fun at times.  I always had a hard time getting my hands on NAVSEA stuff - scans were much easier to find than the super nice real PDF versions that were searchable (super time saver there).   And, yes, everyspec can give some obtuse results at times.  There have been times when I've entered a spec number and gotten stuff completely irrelevant to the spec on interest.  Though finding the spec number to begin with is usually the adventure - hence my question here. 

The spec junkie in me is kinda curious if MIL-STD-2000A was superseded by a commercial spec or not.  After spending time working with Mil-Specs, and understanding the role and evolution of commercial specs over the last 40 years, I understand why there is a slow but steady movement toward adopting commercial specs where it's possible.
-Mike

senko

Some ideas:
-------------------
The perfect guitar pedal, one which will never break and take all the abuse you can throw at it, is still is going to take a lot of use and abuse.
Regular maintenance is a requirement - something you will never be able to avoid.  There are tradeoffs in the real world.

You want it to be built like a tank. 

The main circuit board should be stable.  Having a switch directly attached to the PCB just sounds like putting stress on components that don't react well to vibrations.  A separate circuit board connected to both the switch and the main circuit board via a ribbon cable is how a lot of the big name manufacturers do it, if they do it all. 

You also might want to fix other components.  Having a clunky switch in your way while you're desoldering a broken jack is no fun. 

Maybe a different type of switching is needed?  A board of switches might be boring, but it could separate the stimulus from the reaction.
$0.02


Check out my webpage http://www.diyaudiocircuits.com and send me suggestions about what you want to see!  I do all sorts of things with audio equipment, from guitar pedals to circuitbending to analog synthesizers.

R.G.

In my day job, I've done the switch mounting thing several ways.

The earliest versions had stomp switch on flying wires. Failures were generally inside the switch, the occasional broken wire.
Second versions had stomp switches (two of them!) on PCB, and all controls PCB mounted, one plane, no lateral stresses. Failures were generally inside the switch again. Very rarely we'd have a solder joint issue. This coincided with the switch to lead free solder and the whole world had issues with broken solder joints then. Our repair tech railed at the switches breaking, not the PCB.

Third version had a mechanical solution to foot stomping, with a mushroom shaped actuator on a spring return, mechanical limits on movement, and a block of foam rubber below the actuator pressing a sealed tactile switch. We've had some actuators fail, but to my knowledge no tactile switch failures.

In versions 2 and 3, all the pots were PCB mounted, and all were attached to the panel with their own nut. Breakage to the pots was entirely limited to someone stepping onto the knob/shaft and breaking the pot internally. I don't remember any pot-PCB breakages at all, but there could have been a couple our tech fixed without telling me.

Looking at the forces involved in a panel mounted switch or pot, the works of the pot or switch are held in that little box under the top bushing. The bushing is screwed to the panel and is a mechanically strong part compared to the actuator and works of the switch or pot. The electrical lugs are held to the works-box, fixed with respect to the bushing and panel. If the switch/pot is well made, none of the actuation forces get to the electrical lugs. The forces are between the actuator (plunger or shaft) and the bushing/box, and therefore to the panel.

External actuations strong enough to bend the mounting panel will generally degrade the tender, chewy insides of the control first. I think I mentioned getting pedals back where a single flying stomp broke the shafts off pots and switches. That was the motivation behind going to a cast-metal box with an up-swoop just above the pots - it took stress off the pot shafts from the never-ending parade of Doc Martins. Worked great. We did that thing driving a van tire over one of these and it worked afterwards. We did that to the previous-generation version of that pedal, and the pressure crushed the sheet-steel casing and then crushed the controls.

Guitarists complained to us that they thought the rugged actuators and cast boxes which prevented internal damage were ugly.

We then decided that what guitarists really want is the world with a white picket fence around it.  :icon_lol:
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

tubegeek

I thought all the guitarist wants is the drummer's girlfriend?
"The first four times, we figured it was an isolated incident." - Angry Pete

"(Chassis is not a magic garbage dump.)" - PRR

deadastronaut

^ no thanks, my drummers girlfriend could nibble sweetcorn through a fence... ;D
https://www.youtube.com/user/100roberthenry
https://deadastronaut.wixsite.com/effects

chasm reverb/tremshifter/faze filter/abductor II delay/timestream reverb/dreamtime delay/skinwalker hi gain dist/black triangle OD/ nano drums/space patrol fuzz//

alanp

... getting mildly back on topic, anyone know of any 1590A flangers BESIDE Solderman's work? (AKA non 3pdt onboard)

Ice-9

The only thing that makes PCB mounted switches/pots/jacks unreliable is badly designed PCB and badly drilled enclosures which could cause twisting of the PCB. When done correctly I believe PCB mounted components to be better.
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

Please at least have 1 forum post before sending me a PM demanding something.