This is driving me crazy..DC Barrel has me over a barrel

[Guitarist335]

Yes, you read that right. So, I build my first distortion unit and it tests great. Now, I have got all this wiring and components in a small box that I could not fit another hair into. But it is still all working well...untill....

The DREADED DC Barrel

For whatever reason, the thread and outer ring of the DC barrel (being made out of metal), must not touch the steel box that the pedal in built in- otherwise, it shorts.

So, how do I insulate it from touching> I tried scotch tape around it. I tried paining the inner hole of in the box that receives the DC barrel.

HELP!!!

[R.G.]

Sadly, there are not a lot of good choices. You could try drilling out the hole to be big enough to accept a cylinder of plastic to keep the metal barrel away from the case, then using plastic washers on each side. Or perhaps making the hole larger so the DC jack clears the entire hole and putting a plastic plate on the outside of the box and mounting the DC jack on that, carefully making the hole in the case big enough that the DC jack really, really clears the edges. You could try casting some epoxy putty into a covering over the part of the DC barrel that the case touches, and again enlarging the hole, or something similar.

I sympathize. I'm a veteran of having to do various sized mods to cases to make the effect inside work. Sometimes, the time and money to make a tiny box work is more than would be involved in trashing that box and starting over with a fresh, un-cut box of the same or larger size.

[Sooner Boomer]

One solution I can suggest will work, but you won't like it. Drill or cut a hole larges than the barrel, possibly larger than the jack. Mount the barrel to a suffeciently thick piece of plastic, them mount *that* to the box. This will totally isolate the connector from the metal box.

[Jdansti]

A sure fire cheap way is to use a plastic jack- with or without switch. Here's an example:


https://www.taydaelectronics.com/dc-power-jack-2-1mm-enclosed-frame-with-switch-external.html

[idy]

That is an unavoidable side effect of the "industry standard" for pedal power: center negative, barrel postive. Metal jacks all(?) assume the barrel is ok to ground, the way virtually everything else in the world is done. So we here use plastic jacks... or in a pinch some kind of insulating washer/ferrule thingy, heat shrink tube might work...

The real fix is to buy some plastic jacks. I think you are going to be needing more!

[j_flanders]

If you insist on keeping the metal 'DC barrel' I think the 'professional' way to do it is to use a 'shoulder washer':
This kind of washer is also used for RCA jacks connecting to reverb tanks where the sleeve is metal and needs to be isolated from the chassis/ground.

[anotherjim]

Something that's found its way into my armoury is the humble grommet. The ones sold for cable protection at normal electrical outlets, but you can get kit boxes of different sizes. Modern grommets seem no longer to be made of soft rubber and are I think better for it. I've used them as intended or sliced in two for washers with or without the middle.

If you have some standard 24hr epoxy, coat the hole (I don't mean fill it!). When properly cured, it can be filed neater to form a grommet that won't fail.

[Guitarist335]

Folks:

Thanks for all the ideas and support. I am still miffed that we have to face this issue. Is there anything that can be done to reverse the wiring of the barrel to avoid this issue?

I notice that there are some great ideas of stuff to use to solve this. I am looking for something that I can purchase on Amazon. Does anyone have a link to something that may work?

Thanks again!

[Guitarist335]

If you insist on keeping the metal 'DC barrel' I think the 'professional' way to do it is to use a 'shoulder washer':
This kind of washer is also used for RCA jacks connecting to reverb tanks where the sleeve is metal and needs to be isolated from the chassis/ground.

They look perfect. Where can I find them? Amazon?

[Ice-9]

Another solution if you really want to use those metal jacks is to just rewire them as centre positive and use an polarity inverting cable from you psu. That of course is presuming your not wanting to use a battery with the jack switching etc.

[Rob Strand]

Another solution if you really want to use those metal jacks is to just rewire them as centre positive and use an polarity inverting cable from you psu. That of course is presuming your not wanting to use a battery with the jack switching etc.

The old 3.5mm jacks had this set-up.   My beef is normally you don't want the power to run through the chassis.    For example if you have a filter cap on the effect PCB the cap filter current pulses end-up getting into the audio.

They look perfect. Where can I find them? Amazon

I guess that's the problem with specialize parts, not so easy to find, especially when they need to be *that* size.

The heatshrink method for insulating the hole is fairly DIY friendly and flexible but you still need to get some plastic washers for the front and back.

I've made plastic washers from plastic milk bottle tops.   Fine for a one-off DIY job but totally unacceptable for a production unit.

[bluebunny]

I am still miffed that we have to face this issue. Is there anything that can be done to reverse the wiring of the barrel to avoid this issue?

This has been an "issue" since BOSS.  So a little late to complain.   

There's nothing to stop you wiring your pedals how you wish, but don't expect them to play nicely with commercial guitar fx power supplies or other people's pedals.

[Rob Strand]

This has been an "issue" since BOSS.  So a little late to complain.   

Actually back in the 70's most plug-packs with "DC Jacks"  were wired like this, so I believe Boss was following the more popular convention of the times.   A lot of those plug-packs were made in Japan (not China like today).   Calculators and radios often used plug-packs.  Then maybe kitchen scales.

In about the 80's  flippable polarity plug-packs were around but most equipment followed the old convention.

A lot of switch-mode type plug-packs for computer equipment going back to say 2000 era to now are the reverse.


Here's a sample of an vintage plug-pack (Sharp brand calculator),
https://www.aaktengroup.com/index.php?main_page=product_info&products_id=625641

[Guitarist335]

I have very little experience building pedals, although I have
Been playing guitar for over 40 years. Given my lack of experience building pedals, I was just surprised to encounter this problem. Thanks to all for the advice much appreciated

[aron]

I used to use those shoulder washers but just went to plastic DC jacks.

[Guitarist335]

I never knew plastic dc jacks existed.  Are they on Amazon

[bluebunny]

They're everywhere: Tayda, Small Bear, Mouser, Farnell, ...

They look like this:



(The second one is for switching out a battery clip when you plug in a power supply.)

[davent]

They're everywhere: Tayda, Small Bear, Mouser, Farnell, ...

They look like this:



(The second one is for switching out a battery clip when you plug in a power supply.)

The switching version is also available with an external nut which some prefer.

[aron]

hahaha you can order them from this site's store.

https://diystompboxes.com/zencart/index.php?main_page=product_info&cPath=11&products_id=36&zenid=9tqb2q7th24knqjqudvb8shm65

[Guitarist335]

I found some on Amazon.  30 for 13 bucks.  I didn't know this site had a store