Power from adapter does not power pedal

[Badcircuit]

Hi,

This is probably a simple question that has been answered before.

I have a board I'm working on whereby the 9 volt battery connection works, the wall adapter when plugged in does not work.  The pedal is together on its switch ready to go into its enclosure.  I'm new to pedal building so this is probably a simple topic.  Again, tge battery powers tge pedal, tge 9 volt adapter does not.  The adapter is good.  This scenario occurs when no batter is connected, just the 9 volt plugged in.  Any help would be appreciated.  Thank you.

[RickL]

So the 9 volt adaptor works for sure? You've used it to power another pedal, not just checked it with a multimeter?

Assuming this is true, which I do, two possibilities come to mind. Either the wiring to the jack in the pedal is incorrect, so you're not actually getting 9 volts to the pedal, or the polarity of voltage once it gets to the pedal is incorrect. Any chance that the pedal uses a positive ground?

So check to make sure 9 volts is actually getting into the pedal, and make sure it is the correct polarity (this could also be caused by a wiring mistake).

[idy]

Most common mistake that causes this is mixing up the two terminals on the 9v jack that, in our use, get "red" wires. There is a larger terminal that goes to ground,(usually black wire) and two terminals for "red", one going to the battery, the other to the circuit. The one intended for the battery is "normally closed" meaning when nothing is plugged into the jack, the battery + goes to the pcb. but when you plug a jack in, that wire's connection is lifted and it goes nowhere.

So if you get the two terminals mixed up you get power from the battery, but not from external power.

[bluebunny]

FYI, if the tabs at the back of the DC socket are aligned thus:

       _
         _
     |

then the left-hand vertical one is ground.  The top-most horizontal one is the +ve power connection to your circuit.  The other (right-most) horizontal one is the +ve battery connection.

[Mark Hammer]

Bluebunny has it right.  All too easy to use the "wrong" solder lug.

Another thing to be mindful of is the depth of the jack/plug.  There are two standard plug lengths and associated jack depths.  If a "short" plug is inserted into a "deep" jack, it may not push the contact that switches between battery and external power sufficiently to provide power to the circuit.  It's not likely as common a problem as mistakenly using the wrong lugs, but it happens.

[Badcircuit]

Hi Guys,

First off, I really appreciate the help.  I do have it wired correctly.  I've checked that against what was recommended. And diagrams online.

I even reversed it and still got battery power but no adapter power.  So I'm thinking it might be the socket itself.   But I want to check with the group go out and buy a bunch.

I had the board and everything outside of its enclosure.  I had the jack wired as recommended. I plugged it into the barrel jack, no power.  Again, the adapter works in other pedals.  Would you all agree that it is most likely that I have the wrong size barrel jacks?  I have noticed that the 2.1mm and 2.5mm look identical.  I want the 2.1mm ones - correct?

Could there be anything else I may be doing wrong?  Thank you!

[antonis]

Are your wiring connections identical to those below..??
(focus on Power, IN, OUT and Battery..)

[Badcircuit]

Yes, for the most part.  I mean my 3PDT is wired differently.  And I do not have the resistor/capacitor running to ground; e.g. 10uF.

Could there be a problem with the way I have the input jack wired? I'm using a panel Mount and have the orange running to the tip, the blue to the ground lug and the black to the ring.

I just don't get it guys.  You think I should post my board layout?  When the voltage is connected directly to the board, the pedal works fine.  It's just when it's on the switch.  What else can I show you to help with the trouble shooting?  It's my own board I made.

I appreciate it.  It's driving me mad.

[Mark Hammer]

I just finished troubleshooting a pedal I boxed up this afternoon.

Power worked fine, as evidenced by the status LED, but there was no signal passing, just a loud hum.  <insert facepalm> The jacks I was using for the bare-board-sitting-on-a-desktop were different than the ones installed in the enclosure, so I desoldered the leads from the jack and board, and wired in some new leads to the pre-installed jacks.  But, silly me, I neglected to connect their grounds to the board. 

That cured the loud hum, but I still wasn't getting any effect signal.  Took a little while, then it occurred to me that maybe I had the "send" wire from the stompswitch going to the "out" on the board, and "return" wire connected to the board input.  <insert 2nd facepalm>  When I was populating and testing the board and controls, minus the stompswitch, I had used the same colour wire for in and out.  Normally I like to use different colours for different functions, and also prefer stranded to solid-core wire, so I changed to the stranded colour wire, but in flipping the board over, during boxing-up, I forgot that in was on that side and out on this side.  When I finally connected the wires to the right pads, I had sound.

It's always stupid stuff.

[idy]

Yes, it cold be a wrong size jack...But:
Do you have a meter? Have you checked the terminals on that jack to see if voltage is on them or not for sure?

[Rodgre]

What kind of power jack are you using?

This is such a basic thing that I feel like I'm insulting everyone by asking, but you're not using a metal DC jack, are you? If anyone doesn't realize this, with "Negative-Tip" 9vdc power adapters on a pedal with a metal (grounded) enclosure, you must use plastic DC jacks, or else the positive of the power supply will short to ground through the metal of the sleeve on the DC connector.

For those of you that know this, please ignore me.

I'll go back to my cave now.

Roger

[GibsonGM]

^ That's NOWHERE near a bad suggestion or one to feel 'ashamed' about bringing up...

[duck_arse]

have I asked for photos-of-what-you-have-built in this thread yet?

[Badcircuit]

Hi Guys,
I hope you can make out my photos.  I changed the 9 volt barrel jack to another I had in my parts.  Now I'm getting power when it's plugged into the adapter, but no power on just the battery.  This is absolutely driving me mad.  I hope someone can see my problem.  Yesterday, on the other barrel jack, I had the reversed problem.  I really feel stupid.

[Rodgre]

I will suspect that the issue is now where the switching lug on the DC power jack is not wired correctly. The Battery + connection needs to go to the switching lug so that when there is an adapter plugged in, it completely disconnects the battery from being able to accidentally have the DC adapter send 9v to it and go boom.

Can someone confirm this for me? Off the top of my head, the circuit's +9v battery connection must come from the "bottom" sleeve lug on the DC connector and the battery to the "inner" connector (which is the shorting "switch" lug to the sleeve) and the ground/- connection is the largest lug that is in the middle.

Roger

[Badcircuit]

PS - Please note my wire colors do not follow the standardized pedal colors.  Green and Black are grounds.  The black on the jack is going to the barrel jack.

I noticed when I hook the 9 volt directly to the the wall dapper lug, the 9 volt battery works.  I've changed them back the way they should be. 

I should have mentioned in my previous post that on the multimeter, power is getting to the board from the adapter lug.  Power is not getting to the board from the 9 volt lug.

I'm starting to think I have bad barrel jacks.  This is not restricted to this pedal.  I have other designs that are doing the same thing.  The boards are all done like the example; I.e, with the connection pads to the left of the board.

Thank you.

[antonis]

I will suspect that the issue is now where the switching lug on the DC power jack is not wired correctly. The Battery + connection needs to go to the switching lug so that when there is an adapter plugged in, it completely disconnects the battery from being able to accidentally have the DC adapter send 9v to it and go boom.

Exactly..

[Badcircuit]

I believe I have it on the switching lug.  Please look at my photo.  I have the battery on the lug right above the ground lug and the wall adapter right on the top lug.  Can you confirm if that is correct?

[antonis]

I DO confirm it is correct..

[Badcircuit]

You confirm I have it right?  Not trying to be thick.