Puzzling power question for the Double Flush

[mshuptar]

Hey everybody, this is my 3rd non-kit build and I haven't encountered this problem before. I'm working on a Double Flush and I think have a power problem. When I first tested it, nothing happened at all. No led, no sound, etc.

However, when I used an alligator clip to join the two +9v terminals on the power jack, the effect worked. (I stumbled on this when I pulled out my DMM to start troubleshooting and the tip of my DMM contacted both +9v terminals.) It's also worth noting that when the effect is powered up, the hum is loud enough to be sort of annoying and the hum pulses with the effect.

So here are my questions:
1) Are these serious problems?
2) Do I just solder a piece of wire between the two +9v terminals?
3) Is there a way to reduce the hum?

Other relevant info: I subbed a 3.9M resistor in R18 because I didn't have a 3.3M. I'm also using a 1776 Effects 3pdt board. (I don't know if this info is relevant or not.)

Any insight would be much appreciated - thanks!

[Thomas_H]

You may have wired the Powerjack in a wrong way.

The GND pin seems to be correct. The unswitched power pin is the one closest to the outside plastic ring.
It looks like you have picked the switched one. Try using the other pin and check if you have power all the time now.


Not sure about hum. What power supply are you using?

[wstimson]

Yep, sounds like you've used the wrong 9v terminal on your DC jack.  Switch it and that should do it.

As for the hum... hard to say for sure, but I'd guess it might be a grounding issue.  Post a picture or two of your build and we'll see if there's anything suspicious.

[mshuptar]

Both of you were correct. I used the wrong 9v terminal. It was that simple! (I'll also admit that, until now, I didn't really know that it mattered which terminal I used. Live & learn, I guess)

The best part is that this took 5 minutes to fix and everything sounded a lot better - including the aforementioned hum (which still exists-but it's not as annoying, and it's probably due to my cheap adaptor).

Thanks for the help!

-M

[alanp]

Easy way to avoid the wrong jack, just twist them a bit and have the 9V wire going through both  (I'm lazy, that's what I do these days. It's nice when things are easy fixes like this.