my pedals are somehow getting dc-, will this kill them?

[sjaltenb]

hey,

well i had my Cornish board up and running perfectly. All the effects sounded great, no noise, no pops when effects engaged, anything. it was beautiful. keep in mind i am not running it off its own power source yet, but using a OneSpot and a power jack to tap into the power and ground distributions i made.

so since everyting is going so well i decide to move the board down to the floor from the table where i have been working so i can play around. I unplug the power, put the board on the ground, and plug the power back in. now every effect is making the same sound as when i accidently connected a DC power jack backwards. its that loud du du du du du du du sound. the thing is, i disconnected the one spot from the 2nd power dist. board, and those effects are still making that same noise!

im guessing somehow one of my connections came loose somewhere and my 9V+ is connected to ground...right?, becusae it WAS working PERFECTLY, until i picked it up. What I am wondering is, if i keep the power plugged in to try to sort this out....can i do damage?? I can also note if the effects are getting proper power cause my CS2 LED will light up. I was fiddling with something and i look over and its on, then off again.

I just dont want to do any damage, but i dont know how to sort it out if dont keep it connected. Also, this may be a elementary question, should there be continuity between the ground and the 9V+ power in on the boards?

thanks yall...it was so cool when it was working!!! i gotta figure this out!

[R.G.]

You don't need the power on to figure out where the wires go. Use your ohmmeter setting.

[sjaltenb]

well i cant find any loose wires, thats the problem. theres nothign physically loose or any power/ground connections that are bridged, etc.

this is going to be a tough one to troubleshoot...

[tranceracer]

Just curious if the noise goes away if you move the effects to your work bench?

-tR

[sjaltenb]

nope it doesnt go away. i even disconnected the whole power distribution system and only hooked up my adaptor to a single effect and i had the same result. my guitar signal is going all the way through no problem when everything is in bypass

Is there any way i could have damaged all the effects if something had touched or happened? I just cant figure out whats wrong, it was working perfectly. I have checked all connections with power/ground and signal. Im really perplexed at the fact that the same thing is happeneing when i only connect the adaptor directly so a single effect.  Its the exact same sound as the time i accidentally connected my power jack backwards to an effect  (positive to ground and ground to positive).

And yes, i checked the adaptor and it works perfectly.

[sjaltenb]

ok well i did some troubleshooting.


This is what happens. The effects are still working perfectly fine.

I connect the positive to the positive connection on my power bus, and the negative to the ground bus. If this is all i do, the effects work but there is a horrible hissing noise. this is just as what happened last night before i got the unit working perfectly. So last night, i connected the ground bus to the enclosure, and this is what silenced the noise and it worked perfect.

Now if i connect the ground bus to the enclosure, i get the wierd du du du du du  du noise-the same noise as when you reversly connect your power and no effect signal at all. also, now i get HUGE popping noises when i switch on effects. I have NO LEDs connected yet.

I just cant figure out the issue here, i am connecting everything the same way as i did last night.

[PerroGrande]

Are any of your effects positive ground? 

Is anything common to the enclosure that shouldn't be?

The reason I ask is because it sounds like when you ground the enclosure, something is shorting out the power supply. 

[sjaltenb]

Thats exactly what it seems like is happening.

All the effects are negative ground, i havent changed any of that wiring.

My ground system goes like this: All shielded cable grounds to the enclosure. All the 3pdt switches connect to bus which is connected to a different Ground bus, which is connected to the negative on the power supply. My input/output jacks are connected sleeve to enclosure.

when it was working, i connected the ground bus to hte enclosure to silence the hiss, which is NOT the same as the du du du noise. sorry thats teh best i can describe it, like a loud fast thumping.

[R.G.]

If you're still using the 1Spot adapter, it is refusing to kill your pedals.

A 1Spot with a shorted output will repeatedly try to bring up the voltage on its output, see that it can't, and shut down for a brief time; then it tries again. That could be what the loud fast thumping is.

I think you have something shorted to your enclosure that should not be. And the more you check over it in the same way every time, the harder it will be to see. That's why I prefer the ohmmeter method. Disconnect the connection to the enclosure. Then use your ohmmeter to see where the enclosure connects. It's going somewhere and you can't see it.

[sjaltenb]

R.G.

Thats gotta be what it is.

Now, I have to admit, i've built quite a monster, and i dont even know how to properly use a DMM! Is there any way you could give me a quick explanation of how to do this and what to look for?

Ya'll have been so much help, when i finally get this thing running i will certainly owe it to everyone on the board.

[kvb]

well, I think that you should be using the continuity tester mode.

when your meter is set to this selection, you will hear a beep when you touch the two probes together.

If you wanted to know if a part was connected or not, you would touch it with one probe and tuch the rest of the circuit with the other - if it beeps the part is properly connected.


You are going to be testing to see what part of the power supply in one of your circuits is touching a ground.
So, once yer meter is in continuity mode, you're going to aligator clip one of the probes to ground and then start touching the power leads to see if you hear a beep.

You may have to disconnect each circuit from the power supply in order to find which one is grounding out.

[sjaltenb]

ok yeah thats what i've been trying to do, but i will do it more systematically this time. If one is grounding out im guessing it would cause them all to ground out, as they are connected to a bus, right?

soemtimes my DMM goes crazy and i will only touch it to one thing and it beeps and goes crazy, which i dont understand. i will try to get some pictures up soon to help.

[PerroGrande]

Yeah -- I think pictures will help us.  Without being able to see your enclosure, I'm kinda shooting in the dark when I say something like: "remove all but one effect" etc...

[sjaltenb]

FIXED!

Ok firstly thanks to eveyrone who replied.

I narrowed it down to the dynacomp that was cuasing problems. So i pulled the pcb off and started looking around, found a few things which i thought were the culprit....no luck. So i get pretty frustrated.

So then i look up under the board by the pot...and found....a single strand of braided shielding from my shielded cable. i pulled it off...and VOILA! Now, the only problem is i cant get my CS2 to power back on...it used to be all i had to do was touch the wire to ground and it powered on...now i get no signal/noise/anything when the 3PDT for it is switched on....could i have fried it?? any suggestions welcome.

Thanks!!!!