Help regarding pcb mounted 1/4" jacks

[Ice-9]

There are a couple of important things to take into account when using PCB mounted jacks with Hammond type enclosures with trapezoidal walls.
The first thing you would notice with PCB mounted jacks is that the external nut does not pull the jack tight against the wall of the enclosure but in fact the diameter of the hole drilled through the enclosure wall is larger than the diameter of the jack extrusion, which really sits in the enclosure hole.
The outside surface of the enclosure is still sloped though so some twist on the PCB may happen, PCB slots around the jacks provide the needed flex (which is very small)this can be seen in the picture of one of my PCB's below  This then provides a solid mount from the jack nut as long as everything is measured and drilled correctly which also isn't a difficult job.
Thirdly, jack nuts don't need to be torqued that tight, they are not holding the space shuttle together.

[ElectricDruid]

Thirdly, jack nuts don't need to be torqued that tight, they are not holding the space shuttle together.

What?!? You mean the jack nuts won't survive re-entry from orbit?!? I can't believe it! I'll never accept it! Only the best for my pedals! They must be able to be fired into outer space and re-enter far-away alien atmospheres without damage. After all, how else will I xsopread my concept of "tone" to other galaxies?!

Tom

[GGBB]

There are a couple of important things to take into account when using PCB mounted jacks with Hammond type enclosures with trapezoidal walls.
The first thing you would notice with PCB mounted jacks is that the external nut does not pull the jack tight against the wall of the enclosure but in fact the diameter of the hole drilled through the enclosure wall is larger than the diameter of the jack extrusion, which really sits in the enclosure hole.
The outside surface of the enclosure is still sloped though so some twist on the PCB may happen, PCB slots around the jacks provide the needed flex (which is very small)this can be seen in the picture of one of my PCB's below  This then provides a solid mount from the jack nut as long as everything is measured and drilled correctly which also isn't a difficult job.
Thirdly, jack nuts don't need to be torqued that tight, they are not holding the space shuttle together.

Those are all good ideas - but they are only just making the best of a less than ideal design IMO. The PCB solder joints are still subject to the stresses of  force from motion and jack insertion/removal.

[ElectricDruid]

I just did a bit of looking up and calculating. The wall slope angle on Hammond enclosures is stated as "2 degrees or less".

Taking two degrees as a worst case, and assuming that the jack socket takes up 20mm of wall space (it won't) then there's 0.69mm of difference between top and bottom of the jack. 15mm is maybe more realistic, and gives you 0.52mm.

Ok, so if our nut is tightened hard to the outside of the box, our jack is not flat to the PCB and consequently the inward end of it should really be fitted lifted slightly off the PCB (so that there is no stress or flex on the joints). Assuming the jack's innermost pins are 30mm from the panel, we get a figure of 1.05mm.
Given that PCB pins are probably 4 or 5mm, this isn't going to cause any problems, although it should be considered and allowed for (or at least mindfully ignored - this is choice, after all).

The easiest solution to this is to use an enclosure with parallel walls - bingo, no problem.

T.

[GGBB]

The easiest solution to this is to use an enclosure with parallel walls - bingo, no problem.

Wouldn't off-board jacks actually be even easier?

[davent]

The easiest solution to this is to use an enclosure with parallel walls - bingo, no problem.

T.

Then the problem becomes sourcing enclosures with parallel sides, precludes anything diecast.

dave

[highwater]

How about just waiting until the board is in the enclosure before you solder the jacks?

[GGBB]

How about just waiting until the board is in the enclosure before you solder the jacks?

If you think that through - it's tricky (but not impossible). You have to have the jacks tight while the jack bodies are still fully inside the enclosure. Your board holes need to be large enough to manage the pins going through on an angle, and your board layout needs to accommodate the connectors being underneath, plus room for components, pots etc. You need to drill your enclosure very accurately as well.

But isn't this still about mistaking that mass-produced look for superior quality? Using off board jacks is easier and more reliable IMO.

[ElectricDruid]

How about just waiting until the board is in the enclosure before you solder the jacks?

Absolutely! Tighten the jacks into the enclosure with them in the board, then solder, no problem. After all, I've done that with LEDs on other projects and I quite often do it with pots too.

If you think that through - it's tricky (but not impossible). You have to have the jacks tight while the jack bodies are still fully inside the enclosure. Your board holes need to be large enough to manage the pins going through on an angle, and your board layout needs to accommodate the connectors being underneath, plus room for components, pots etc. You need to drill your enclosure very accurately as well.

The extra hole diameter required is going to be very minimal, but we can calculate that too if you're interested. It's only 2 degrees off vertical, and the average PCB is only 1.5/2mm thick, so it's not a huge amount. Enclosure drilling is more of an issue and is another reason to put somewhat-oversized holes on the PCB.

But isn't this still about mistaking that mass-produced look for superior quality? Using off board jacks is easier and more reliable IMO.

No, not in my case. If I was designing a PCB for myself alone, yes, I'd agree with you (I *do* agree with you). But I'm designing PCBs that I would like absolute beginners to be able to build as far as possible, and the fact is that off-board wiring is one of the things that people commonly screw up, so anything that can minimise that is going to massively *increase*reliability (in the sense of "I built it! It works!") for me rather than decrease it. So it's not about trying to make it look like a factory unit, it's just trying to reduce the number of wires people need to solder and hence the number they can solder wrong.
Secondly, I haven't done a single project with board-mounted jacks yet, and I don't think it's that likely. In some ways it swaps one problem for another (mixed up wires for inaccurately drilled holes!). But I appreciate the discussion of the pros and cons with you all. It's nice to talk to informed people.

Tom

[GGBB]

It's hard to believe that beginners could be more likely to screw up off-board jack wiring than enclosure drilling, but what do I know. I do know which is easier to fix, however, as I've been there personally  .

[ElectricDruid]

I do know which is easier to fix, however, as I've been there personally  .

Lol! Roger that, millivanillichillywilly!

T.