Boxed In- why doesn't it work when in the box

[SparkyCal]

I have built the a guitar stomp box overdrive circuit. It works great. However, when I put it in ther box and faster the pots and guitar jacks to the box, and close it, it stops working.

The details of this build are in this thread:
https://www.electronicspoint.com/forums/threads/back-to-the-breadboard.295296/


I am thinking that maybe somethings touching the steel enclosure that should not be.

On the PCB , I have a length of bare copper wire across on e of the sides of the PCB, soldered in to act as a ground rail. I wonder if this rail is causing a problem. Or do you think it can be somethign else. The pots and the jacks do make contact with the steel box, as part of the fastening procedure, so I am not thinking that there are the issue.

What else can I check?

Thank-you

 

[bertus]

Hello,

You could use some isolation between the box and PCB.
You could use the plastic sheets that you can find in the supermarket between the pre-packed meat and cheese.
(they will cost you nothing).

Bertus

 

[Harald Kapp]

Use your ohmmeter and measure between:
- contact of battery + connector and box
- contact of battery connector- and box
WITHOUT the battery in place! That should show you whether you have a short circuit (very likely) or not.

 

[SparkyCal]

I didn't see a short there.

 

[SparkyCal]

Bertus and Harald. I think the isolation is a good idea. I’ll try it

 

[WHONOES]

Why don't you put it all into one of the plastic boxes you mentioned in the previous thread and see if it works?

 

[Martaine2005]

Once in the metal box, there has to be either a short or open circuit somewhere if it works outside the box.
If @Harald Kapp 's idea shows no short without battery connected, perhaps you have the PCB sitting on the battery shorting the circuit?
Other than that, it can only be the 6.35mm jack and pot connections. Check you have wired them correctly as they are directly connected to the metal box.

Martin

 

[VenomBallistics]

first guess, your jack polarity.
If wired backwards, you'd be sending your signal to ground.

 

[SparkyCal]

Thanks guys. This was all due to cramming too much stuff in a small box. I am rebuilding it, using a smaller PCB.
Unfortunately, the 1uF caps I have are 50 volts- which means they have large heads.

When I closed the box, all my caps bent, almost breaking them. That made me wonder- I wonder if I should leave more lead wire from each cap, and bend them down to conserve height space. If I designed that in, it should be okay, shouldn't it? I know it's odd but it may be a solution given the small box.

 

[Martaine2005]

bend them down to conserve height space

That is quite normal. Providing you have the space to one side.
Rotate the box once a week though, or the electrolyte will seep out.

Martin

 

[bertus]

Hello,

Does the capacitor have long legs?
Then you could possibly mount it on its side:


Bertus

 

[SparkyCal]

Thank-you guys. Good to hear that I am not crazy ;-)