Reversed power?

[JimmyS2]

Good afternoon folks, ive found myself in the troubleshooting forum.

My first thread here was about sourcing components as I am totally new to this, and several of you where extremely helpful. Now however, I've finally made my way through my first build and... nothin.

I did pretty much expect this, I can't imagine too many people fire up their first build first try, so fair enough. I built the amentum boost, figuring it looked simple, and then chose to stuff it into a 1590a, so it ended up being less simple. Truthfully I spent some time staring at all the stuff I needed to fit into the little box wondering if it was going to be a mistake, im sure its going to make troubleshooting and fixing a lot of fun.



Upon hooking it up, no power. Then I noticed if I touch the end of a power cable to the sleeve (I guess?) The very end of the power jack, the led comes on. Bypassed, the signal seems to go through fine. When the pedal is engaged, signal drops, sounds thin and fuzzy, and of course this is while I touch the power cable just so, otherwise nothing.

Seems like the power jack is backwards, though I triple checked and I dont think so. Unless I dont understand something correctly, which is likely.

If anyone is confident I need to reverse the wiring to the power jack, I would appreciate a quick explenation, just so I can learn what happened. If I need to post some pictures of different angles I easily can, let me know.

 

[Robert]

The longer lug should be the positive lug assuming your power supply is a standard negative tip pedal power supply.

If you have a DMM a quick voltage measurement across the DC jack lugs will tell you if the polarity is correct.

 

[Robert]

Also, insulate your PCB with something more substantial than electrical tape.

Component leads tend to poke through and short to the enclosure... it's not always visible.

 

[JimmyS2]

Well, the longer (sleeve) lug is connected to positive on the board. I'm sure this is elementary stuff, but my power supply shows tip negative like I would expect

But the cables have the opposite shown.

I dont know if that symbol on the cable makes any difference at all, or exactly what's backward here. In regard to insulating the board, will do! Hopefully I have room, its tight in there!

 

[Robert]

Measure on the end of the cable itself.

 

[JimmyS2]

Ok, measuring at the cable shows about -9v, so tip negative I think. It seems I have power when the sleeve of the cable touches the sleeve of the jack, but not when plugged in.

Perhaps I dont u derstand still, or perhaps the jack is faulty? I hesitate to blame the parts haha

 

[JimmyS2]

So, I've ruled out reversed power I believe, I can measure about 9v between the sleeve lug of the power jack and any number of ground points. The diode is not reversed, as far as I can tell all of the wiring is in fact correct. Could I have just burned something in soldering?

Ive removed it from the case, and reattached the power jack so I could test. It is exactly the same so I guess I can rule out something shorting to the case. Ive confirmed polarity of the diode, led, and electrolytic cap, not sure how to check the transistor. As far as I can tell the wiring all seems correct, I was hoping something would eventually jump out at me.