Phase I prototype board - problem with buzz/hum when powered

[effectsbay]

Hello All

I've been getting really psyched on working out some effect circuits, but I thought it would be nice to work on a prototype board similar to the Beavis Board where I can easily play with the pedal and move it around a little easier. Basically, it's a enclosure with footswitch/LED that goes to a terminal strip, which then I would jumper to a breadboard and start working with the circuit. Phase II will be voltage sag and pot 'row'.

Anyway, I got it all wired tonight with true bypass switch, battery hook up and dc jack. Everything works great when I connect input to output, but when I use the DC jack there is a hum when the LED is lit. I get no hum when it's on battery though? I'm guessing a bad ground some where, but everything 'seems' fine when I'm looking at it.

Here is a shot of the board:


Here is a shot of the 'guts':


Bigger photos are here:
http://www.effectsbay.com/files/P3020051.JPG
http://www.effectsbay.com/files/P3020052.JPG

Any ideas?
Thanks!
hank

[effectsbay]

For some dumb reason, I have two grounds coming out of the enclosure and joined at the terminal strip. I'm going to try to get a single ground to come out instead. I doubt that is the problem, but wanted to 'tidy' it up any way. I might also replace the DC jack in case something is bad there? I just have no explanation why the power supply is causing the hum, yet the battery is not. Hum only occurs if the LED is lit up, so I might try to redo the limiting resistor/LED connection to the + side of the DC jack, just in case there is a bad joint there. Any other recommendations/suggestions?

Thanks!
hank

[anchovie]

Does the PSU hum with other effects? Is it regulated?

[effectsbay]

Does the PSU hum with other effects? Is it regulated?

I rewired it last night, removed the extra ground and chained it to another ground lug. Hum still there. I made the DC jack ground be the ground for the board (out) and also connected a ground from the DC jack to input ground and chained the rest.. still hum.

I'm using a One Spot power adapter. I'm not using it in conjunction with any effects, I just connect the send/return to make a connected loop and turn it on.

Now, my new wiring also causes hum when there is no power. I'm starting suspect something goofy with the switch? Not sure where to go from here.

Thanks!
hank

[slacker]

Where does the ground wire on your DC jack go? I can't really see from the photo, but it sounds like something isn't grounded properly to me, so maybe there's a problem with that.

EDIT: ignore that I just read your last post properly.

[effectsbay]

Where does the ground wire on your DC jack go? I can't really see from the photo, but it sounds like something isn't grounded properly to me, so maybe there's a problem with that.

EDIT: ignore that I just read your last post properly.

I agree that there is something wrong with the ground. Do you know of a good diagram for 9V battery and 9DC Jack?. I'm thinking about starting completely over.

Thanks!
hank

[slacker]

Here you go

http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_tb_dcjack.gif

I'd use this, wire the sleeves of the input and output jacks together, then connect one of them to the DC socket ground pin. Then run another wire from the DC socket ground pin to your terminal block.

[effectsbay]

Here you go

http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_tb_dcjack.gif

I'd use this, wire the sleeves of the input and output jacks together, then connect one of them to the DC socket ground pin. Then run another wire from the DC socket ground pin to your terminal block.

Thanks that diagram shows 4 grounds going to the board ground. Is there a way to have one ground (so chaining the rest) going to the board ground?

I also have one stereo jack and one mono jack. You're said "Wire the sleeves of the input and output jacks together". So in this case I would wire the sleeve from the stereo (input) to the ground lug of the mono (output)?

Thanks!
hank

[slacker]

Thanks that diagram shows 4 grounds going to the board ground. Is there a way to have one ground (so chaining the rest) going to the board ground?

It doesn't really matter how you do it so long as all the grounds are connected together and are connected to the ground lug on the DC socket. Chaining them together should be fine.

I also have one stereo jack and one mono jack. You're said "Wire the sleeves of the input and output jacks together". So in this case I would wire the sleeve from the stereo (input) to the ground lug of the mono (output)?

Yeah.

[effectsbay]

Ok.. here's an update. I completely redid everything, and I still get the buzz. After further testing, I've isolated it to the input/output board leads being outside of the enclosure. If tie them together and put them inside the enclosure, it's quiet. If pull them out, I get the buzz.

My question, wouldn't this happen with every breadboard project? Am I missing something?

Thanks!
hank

[effectsbay]

Getting closer now. I used some shielded cables from RCA cables, and it got it quiet from the box to the terminal strip, but it's buzzing from the term strip to the breadboard.. but not bad and acceptable for proof of concept.

Here it is in action with a clean boost on the breadboard!



Thanks everyone for your help.
hank