First time using metal box

[Tombaxter97]

Just a quick question. Do i need to use plastic washers on the components - audio jacks, 9v power supply jack etc - so I don't make the whole box live or something and also is there anything else you need to do that is different to using plastic enclosures.

[antonis]

You must make the whole box "dead" (grounded..!!) to serve as an external interference shield.. 

If you use plastic washers without any internal box grounding, anything "captured" by the box is "transmited" to the internal circuit..

You may use Power Supply's GND for OUT jack sleeve and IN jack ring for PCB grounding..
(IMHO, it's "safer" in case of loose nut - although some people prefer the opposite wiring..)

Only signal and +9V should be isolated from chassis.. 

[patrick398]

In my experience using metal enclosures is a lot easier than using plastic ones as you can use the metal enclosure as part of the ground. Using normal metal 1/4 jacks is fine, no need for plastic washers as the connection they make to the enclosure is part of the ground. There are many different wiring diagrams floating around but this one is nice and straight forwards:

http://4.bp.blogspot.com/-IhNTi22GX_M/T8JmMvmVJNI/AAAAAAAABQ4/GF7tQj0Shks/s1600/StompboxWiring.gif

[arkatom]

Watch out for metal dc jacks cause pedals usually follow the Boss type centre-negative style. If you use a metal dc jack then you will short Power to the chassis without isolating it with a plastic washer. I did this many moons ago


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[Tombaxter97]

https://sc01.alicdn.com/kf/HTB1SuVlLpXXXXXJaXXXq6xXFXXXg/9V-DC-Power-Jack-for-Guitar-Pedals.jpg_350x350.jpg

Thanks for all the replies. I'm using that jack so just to confirm ill need a plastic washer just for this.

[antonis]

If you'll use a positive center plug it's fine without any isolation..

In case of using negative center plug, I wouldn't suggest to use it 'cause it's hard to completely isolate it from the metal box..
(needs two washers - leaving possibly no space for securing nuts - and some kind of body-thread isolation, like a piece of heatshrink tube of legth precisely the same with enclosure's width..) 

[EBK]

(needs two washers - leaving possibly no space for securing nuts - and some kind of body-thread isolation....

or two fiber shoulder washers instead of all that. 

[arkatom]

Yep you'll need to make sure it's isolated on that one.


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