Hum - Ground Loop ?

[lars-musik]

Hum Ground-Loop within enclosure problem

Hi folks,

this seems to be a hopeless mission, but maybe you can help. I recently finished this 24-Overdrives-in-one-enclosure monster and got it humming and do not really get what is going on. The PSU is a Harley-Benton Powerplant ISO-2 but I also tried a Voodool Labs Iso-5 with the same result.

If the thing is connected to the amp and the guitar it hums. If I take the DC-plug out and touch it, it also hums – which it does not do, if the "pedal" is not connected.

The groundin scheme is one bus wire coming from the input jack, connecting all TRS jacks (which allow the single circuits to be patched separately) and all circuits. The 3 rows all have their separate isolated channel from the PSU, so does the LED bus, which feeds all LEDs.

Where do I start? It looks terrible but in fact started out relatively neat...

Here's a little humming video:

https://youtu.be/6wcGa2HoLas

Ground bus:



Finished:

[antonis]

Make each individual TRS/3PDT GND path (connection) on chassis (screw & nut) as well as for DC jack GND..

If you're lazy enough, you can try group star grounding with unpredictable results, like below..

[lars-musik]

The jacks are not isolated. Would they work as grounding point? I'd just have to cut the bus wire (now that you mention "lazy").

[antonis]

The jacks are not isolated. Would they work as grounding point?

Of course they could..

(in the risk of loose splicing anytime/anyplace..)