Help with this finished (Almost) zvex SHO

[Lost_soul]

I finished this Zvex SHO. Finally after many tries everything seemed to work but it had noise before boxing it and i thought that was just it picking some frequencies or something and it will go when i box it. The thing is after boxing it the noise is still there! And the weird thing is the noise goes away completely if i touch the box or any metal part of the pedal like pot and switch.

I think it's a grounding issue but i grounded every thing that needed to be grounded.

Another weird thing is that the LED stays on for a few second when disconnecting power then it dims until off. Btw i used the Millennium bypass for the LED (also i used 3 diodes instead of 1 to get the leakage required for the LED to light)

So please, what could be the problem and how could i know where it is?

Here are some pics: and ofc i didn't test it like that. I mounted the pot and switch. But i took them out as the box open with a Lid from above.






Also here is an audio of the noise i am talking about.

[idy]

Looks like those jacks do not ground. The Enclosure is probably not grounded, and so is doing nothing to help with noise.
Maybe run a ground wire to a washer that you can put on one of the jacks... or to a sheet metal screw in the box, or... Or use the old-fashioned metal body grounding jacks.

[Lost_soul]

But why don't the jacks ground?

[stallik]

Because the Jack bodies are plastic which is a pretty good electrical insulator. It looks like you have run a wire between the ground terminals on both jacks. You now have to connect that to the chassis as well.

[bluebunny]

The enclosure appears to be finished on the inside?  If so, you may meed to remove some of the finish too.  A washer needs to touch bare metal.

[antonis]

And just to earn peace of mind, shorten (cut) enough both MosFets legs..
(the one in Millenium bypass shouldn't contribute to interference, but..)

[Lost_soul]

Because the Jack bodies are plastic which is a pretty good electrical insulator. It looks like you have run a wire between the ground terminals on both jacks. You now have to connect that to the chassis as well.

But the sleeves of both jacks are already grounded as i connected them both with a wire then another wire to the ground row in the board. And from there there is a wire going to the ground of the power plug. Doesn't that mean they are already grounded?

[Lost_soul]

And just to earn peace of mind, shorten (cut) enough both MosFets legs..
(the one in Millenium bypass shouldn't contribute to interference, but..)

Okay i will do that, i forgot to do it

But what could be causing that grounding problem?

[antonis]

But what could be causing that grounding problem?

Your enclosure ISN'T grounded..!!
(no circuit shielding..)

See dashed line below:

[Lost_soul]

Your enclosure ISN'T grounded..!!
(no circuit shielding..)

See dashed line below:

So even though i connected the sleeves together with a wire and then another that goes to board ground isn't enough?
Btw here are my ground connections just in case:

1st: input sleeve>output sleeve>board ground
2nd: board ground> power socket ground.
3rd: Millennial ground> power socket ground

[antonis]

My dear Doctor..

Plz find a way to connect any bare metal enclosure point to any convenient circuit ground, or better directly to Power supply GND..

You see, your circuit grounding is OK but you DO need to also ground the enclosure..
(or else, it should behave like a plastic box which do not prevent interference from entering the circuit and further be amplified..)

Faraday cage
Scroll down to fig. 6 (About grounding)

P.S.
After retrieving ciurcuit's "quiteness" we'll be ready to argue about star grounding and ground loops..

[duck_arse]

about your led - forget it. what happens at power on and power off are of no concern - at least no concern if it works correctly in use. it is stored energy leaking away through the led.

your jacks are plastic, and insulate from what they mount to. your DC socket is plastic, and insulates [in our case, has to insulate] from what it mounts to. your board is not having a wire connecting to what it is mounted to, so is insulated from it. so all your things are isolated, insulated, from the metal enclosure, until you connect a wire from a point in your circuit you name ground or earth or common, and the metal enclosure - top and bottom.

if the jacks were the metal bushed types, they would connect the sleeves to the enclosure, and the metalwork would be grounded. I hope I've covered all eventualities.


and a question arises - where do you put your sandwiches now?

[Lost_soul]

My dear Doctor..

Plz find a way to connect any bare metal enclosure point to any convenient circuit ground, or better directly to Power supply GND..

You see, your circuit grounding is OK but you DO need to also ground the enclosure..
(or else, it should behave like a plastic box which do not prevent interference from entering the circuit and further be amplified..)

My dear antonis...

I connected a wire from the sleeve of one of the jacks to a washer that i installed on the toggle switch from the inside and that made the noise go away (except for that buzz noise which i have always that disaster when i touch the strings whatever i use because my electricity is trash but that's okay)

I noticed 2 other weird things! (I guess that build is cursed hahaha)

First that when i adjust the pot there is a loud crackle and specially when reaching all the way clockwise there is a pop lock like sound that you can hear  here

Second thing is when the effect is bypassed and LED is off,but upon adjusting the potentiometer counte-r-clockwise (specially when done quickly)  it makes LED light and when stopping adjusting the pot the LED goes off

[GibsonGM]

Yes, as the others said - the metal enclosure is one big shield if it is grounded. It will reject radio interference, computer noises, noise from lighting and other sources.  Shielding is a great thing!  So, some ground wire must connect to the enclosure, in a solid, reliable way.  The more high gain a circuit is, the more important this becomes, since any noise is amplified many many times.

I use the metal brushed type that Duck mentions - the jack body itself provides the ground connection to the enclosure.  I make sure to use a ground wire on BOTH jacks, because if the one without it comes loose it makes terrible noise.


***just saw your post - maybe check that the bridge of your guitar is connected to ground, solidly.   

A star washer with a solder lug is good to ground your enclosure! As long as it will stay tight.


This  circuit has some DC on the gain pot - so "crackle ok"     It is a feature, not a bug.  Others have mods to lessen it, if you search on this forum; it doesn't bother me, personally.

[Lost_soul]

and a question arises - where do you put your sandwiches now?

I connected a wire from a sleeve of one jack to a metal washed that is installed on the toggle switch from inside and that solved it!

Mike told me that the crackle is okay in this pedal and it's actually fine as it's the type of pedal to just set it and forget it.

[Lost_soul]

***just saw your post - maybe check that the bridge of your guitar is connected to ground, solidly.   


This  circuit has some DC on the gain pot - so "crackle ok"     It is a feature, not a bug.  Others have mods to lessen it, if you search on this forum; it doesn't bother me, personally.

I will look into the guitar wiring later as i have no idea about how everything is wired

The crackle is okay but it's that very last bit when you reach the fully clockwise position on pot that is a little loudly annoying but i guess i will just set it and forget it.

Only thing i don't understand now is why The Led light up when adjusting the pot counter-clockwise  here

[GibsonGM]

Sorry I can't help with the LED - I've never used the millenium bypass...

Anything 'moveable', generally a pot, that is in the DC path will make noise. A lot of older amps have this problem with their presence controls.  The pot wiper isn't perfect, and it skips a little bit as you turn it. This causes the DC level to suddenly jump around, and that sounds like crackle. 

Many of these kinds of pedals were sold with a label on the gain control that says "Crackle OK", ha ha!

[FiveseveN]

Only thing i don't understand now is why The Led light up when adjusting the pot counter-clockwise

The pot is changing the DC bias of the MOSFET and consequently the voltage on the output cap, which discharges through its pull-down resistor, creating a voltage that the Millenium circuit detects. You can mitigate it by using an appropriately sized output cap for the load instead of the 5s time constant the original provides.
You can also look for the "crackle not OK" version or the typical AC bypass gain control which should solve both the crackle and the LED issue.

[antonis]

You can also look for the "crackle not OK" version or the typical AC bypass gain control which should solve both the crackle and the LED issue.

I'd suggest an inspiration of the moment improvement:

[GibsonGM]

I will have to try that mosfet boost, Antonis!