Enclosure only problem..

[pete27]

Hi all,
Ive only been building effects for a couple months so im a relative noob.. But i have a question i was hoping someone can help me with:
I built the EHX Screaming Bird/Tree the other day outside of an enclosure (was waiting for the boxes to arrive) and then today got the Hammond enclosures in the mail, drilled the holes, put in the effect and all i got was a horrible crackle/crap sound only when i strum hard enough. So i took the effect back out of the enclosure and it all works perfectly again.. Then back in it and it does the same thing. So obviously the circuit itself is ok as it does all work, but something goes wrong if i want to put it in the box! Im assuming this is some kind of shorting/grounding issue with the box, but ive checked everything over and i cant figure it out.. i was just wondering if anyone knows possibly why this might be happening?? I have a feeling its something simple i havnt learnt about yet..
Oh also i lined the inside of the box with duct tape as i thought maybe my circuit was shorting out, but its definately not, so im assuming it has to do with my output jack...? Because true bypass works fine.
Any help would really be appreciated, thanks

[Ice-9]

I don't have the schematic for this effect, is it a positive earth circuit, if so that may be a problem when mounted in an enclosue, maybe a photo of your build would help in anyone trying to help.

[ghostsauce]

I'm new at this too, but it sounds to me like it could be a bad solder joint that doesn't act up until it's squished inside a box and stressing it.  Try wiggling the parts while it's out of the box maybe?

[CynicalMan]

Check out the first symptom here:
www.geofex.com/fxdebug/newfx.htm

[Mark Hammer]

Whenever I have built something for the first time, and am essentially improvising when boxing it up (i.e., the wire leads are not pre-measured/bent in precise anticipation of where everything is going to go), there is a high likelihood that all the twisting and turning results in a wire being fractured somewhereé  Sometimes the fracture is not visible because the insulation has melted onto the solder lug and one mistakes insulation in place for a non-fractured wire.  Trust me, it happens.

All of this is why I make it a standard practice now to use a piece of heat shrink to cover any solder joints between switch/pot lugs and wire.  This performs two functions.  First, it acts as strain relief to prevent any wire fracture (though it can still happen on the rare occasion).  Second, it insulates solder lugs so that when you are twisting the securing nut for a toggle or pot on the outside of the box, and don't see how you may be shorting something out on the inside of the box, the heat shrink can prevent things from accidentally making electrical contact.

Handy stuff to keep around.

[pete27]

Thanks guys, I've gotta get myself some heatshrink for sure. I'm pretty certain a connection is shorting out on the box somewhere But I just can't see it. 1590A boxes ey..

[arma61]

1590A boxes ey..

yuo should have stated this in advance     those are really hard to wire up

+ 1 on something shorting in a so narrow space

[petemoore]

  I used to line the areas of questionable non-contact with electrical tape or better [something not so easily cut through like clear plastic sheet [like expensive and other stuff is packaged in in stores].
  Cut to size [to cover bottom and most of the sides] carefully shaped and placed. Paper templates to get the size/shape nearer perfect makes the final workpiece product easier to get right', out of the first sheet of plastic.

[pete27]

Ok another problem.. Works perfect when i use a battery to power it, but when i plug a normal Boss 9V power supply into it it does the crackle thing again. Im stumped.. Battery is putting out 8.4V, power supply puts out about 8.9V, hardly any difference, im quite confused..

[Cymastar]

Sounds like a short in the +9V or Ground leading to the power adaptor...

[rousejeremy]

That happened to me before, turned out it was the 1/4" jacks. I'd loosen the bolts and everything was fine, tighten them up and no signal.

[01370022]

It could be the style of the DC plug. If the body of the plug is metal and this is electrically connected to one of the lugs and you're using a center-negitive power supply (like most normal guitar FX) then the positive power on the sleeve of the DC jack will short out on the effect chassis (connected to ground through your leads).

Sounds like this could be the problem. I had this happen on my first build for a friend. Took me until 2am to figure it out.

If that fails then I'd get out the meter and with it boxed up go through major nodes in the circuit testing for continuity to ground. Check power and half rail voltages too

[Hides-His-Eyes]

Sounds like yet another victim of the metal DC jack mistake to me.

[pete27]

Hmm no ive already been through the metal dc jack problem Got that one sorted a while back and got some plastic dc jacks. The wires arn't shorting because if i attach the black and red battery leads with the battery in the clip to the exact point where the the positive and negative is connected to the dc jack then it will work! Just not with the power supply. Have tried a different power supply, no luck. Have tried the same style dc jack on another one of my builds and it works fine. Looks like this may be a tricky one..

[Unlikekurt]

Could you maybe have the positive lugs of the DC jack wired backwards?
ie: when you plug in the power supply it swithes to the other positive lug?