How to safely "float" boards...

[tehfunk]

I wasn't saying I needed screws through the box, I am simply asking about ways to not mount the board to the case or pots in any way, but to leave it floating and be reliable. BTW, what did you mean by on the pot thread, do you mean the back of the pot?

The thread is the part of the pot that you put through the hole in the box and screw the nut down on.  I sandwich the bracket between the pot and the box.  I'll post a photo later.

Peter,

I understand now, yeah, I'd love to see a picture, that method sounds great, even though it's not floating, it might be a good alternative.

[blanik]

margarine containers, i cut tho top in the shape of the pcb and stick it to the solder side, the solder peaks can't go through that... sometimes they can go through electrical tape or thinner material but never plastic containers 

the problem is that sometimes the fit is tight and you need to press the pcb a little to close the cover, thin material will puncture over tiome...

[ClinchFX]

I understand now, yeah, I'd love to see a picture, that method sounds great, even though it's not floating, it might be a good alternative.

Here are the pictures.

Bracket and pot


In box


PCB attached


The bracket can be brass, copper, tinplate if you want to solder it to the PCB, or a non solderable metal if you want to attach the PCB by some other means.  The shape doesn't have to be the same as mine.  The thin bracket still allows the PCB to move a little, but it's not literally hanging on the wires.  I also stick some thin self adhesive foam rubber to the back of the box to protect against short circuits.

I use Cliff insulated jacks and therefore the bracket is the only connection between the box and the "star ground" which is the PCB backplane.

In mass produced gear I've worked on, I've seen nylon self adhesive PCB standoffs like these


If you clean the inside surface of the box with isopropyl alcohol, they stick well and stay there for a long time.  They are a good alternative to the bracket if you're not into star grounding.

Peter.

[tehfunk]

My original reason for wanting to do loose boards was to fit builds into smaller boxes. After hearing a lot of the negatives, I just wanted to be sure that the method was worthwhile, so would you agree that "floating" the boards actually does save space, or do they consume the same space as mounting with standoffs and the like which take up actual drilling space on the face of the box in order to be mounted?

[Pushtone]

The bracket is an elegant solution. I saw another chap here do the same thing off the footswitch.
And another who just left extra PCB board to fit a hole for the footswitch and mounted the board directly to the switch.


HOWEVER, the original question, ahem, is about "floating" the board and I'm not talking earth here!   
I have a few builds that worked out so well, that the insides where as nice or nicer to look at as the outside.

But several of my builds do "float" for various reasons and they are fine because
the wire leads pass through the edge of the PCB providing for strain relief.

This works 101% of the time for your off-board wires.
As a benefit you can man-handle that wired up PCB all you want.
Your off board will not break. I guarantee it*

All you have to do is leave a little extra board around the edge.
Works with perf too! [pic]

Insulation is the next thing you have to do and that is very simple.
But the reliability comes from the strain relief you get.
I only insulate the lid of the box with the sheet foam. [pic]
The plastic margarine contain is a fab idea.



I'm sorry I didn't think of this at the beginning of the thread.
It would have saves us all a lot of time that could have been used building
stompboxes or making an emotion deposit into the relationship bank with the wife or girl friend.

The BEST way to float the board, hands down.



*in the event that you should experience a wire break at the board end on a properly drilled and solder board using the above technique I will build you up another board with all off board parts ready to mount, out of my own stock, guaranteed.

[kawayanstrat]

i use double sided tape or glue and secure it to the back of the pots.

+1 on the double sided tape!

[selectortone]

I have been using double-sided adhesive foam strip for 30+ years and never had a problem with it. I like the extra thickness of the foam over double-sided tape because it compensates for the unevenness of the board caused by the solder joints.

[Stellan]

The top side of the board CAN short out. I have had good results wrapping the entire pcb in thick plastic. It may not be a very authorised way to do it, but it works and keeps everything in its place

Would the electrolytic example I mentioned be a cause? I know exposed leads from vertical resistors can cause shorts on component side..

Yes the top side of the electrolytics can make some kind of short IMO. I dont know much about the composition of electros, but i´ve tried touching the top of one as the effect is plugged in and it made a serious hum and signal disappeared.
As for the reliability of "floating" PCBs, I actually like it, because i always box my effects up as soon as the are working, then take them out for a rehearsal with some band before i start changing components and other mods. I make sure there is enough boubble wrap or plastic in the box that nothing can move around, and it is easy to access the board for modding and servise (plus i get rid of some plastic that would just have gone in the trash elsewise . Rubber standoffs dont suit me at all, because they go loose if you dont leave the board alone. If I where selling the pedals i probably would not do it the way I do, because it doesn´t look too great to have plastic all over the plase. For some people it is important that the inside looks good. For me, i don´t care.