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What would cause a pedal to work with a battery, but not a power supply?

Started by MikeH, December 01, 2015, 09:05:44 PM

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MikeH

December 01, 2015, 09:05:44 PM
The pedal in question is a boss CS3, unmodded.  Works fine with a battery, but with a power supply the LED is dim, pedal has distortion in the background, and I am only getting about 6.7v everywhere I should be getting 9.6v.

I tested it with multiple different wall warts, so that is not the culprit.

Already ruled out power filter caps, reverse polarity diode, and the DC jack itself.

What would cause this and why doesn't the problem present itself when using a battery? Would it be because there is some drain in the power section and the PS cant keep up with the current draw, but a battery can? I'm stumped.  :-\
"Sounds like a Fab Metal to me." -DougH

GibsonGM

#1
December 01, 2015, 09:15:17 PM
Hmm, I hear ya - sometimes it makes you feel stupid, doesn't it?!    How about - there is a bad ground somewhere, associated with the DC jack??  Some connection that isn't right.....(?)

I've seen this before, and believe that was the culprit...strange one, though!
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J0K3RX

#2
December 01, 2015, 10:53:52 PM
Do you have the older version of the CS3 or the newer version?

The manual for the older ones use the Boss ACA unregulated adapter and the newer ones use the PSA regulated.
http://cdn.roland.com/assets/media/pdf/CS-3_OM.pdf

You say that it is getting a voltage drop to 6.7v where you are expecting 9.6v? This may be your problem.
http://stinkfoot.se/archives/726

And the fix..
http://stinkfoot.se/archives/1019
Doesn't matter what you did to get it... If it sounds good, then it is good!

Govmnt_Lacky

#3
December 01, 2015, 11:24:16 PM
^^^ What he said  ;D

Power supply definitely.
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for an amount of 'up to and including my life.'

MikeH

#4
December 02, 2015, 12:30:20 PM
Thanks for the replies guys. I don't think it's a power supply issue, because I was using a one spot power supply for a long time, and it worked fine. I switched from the one spot to a voodoo lab and it started this behavior. Now it's the same problem with any supply I try
"Sounds like a Fab Metal to me." -DougH

ashcat_lt

#5
December 02, 2015, 01:17:37 PM
Quote from: MikeH on December 02, 2015, 12:30:20 PM
Thanks for the replies guys. I don't think it's a power supply issue, because I was using a one spot power supply for a long time, and it worked fine. I switched from the one spot to a voodoo lab and it started this behavior. Now it's the same problem with any supply I try
The link above addresses this specifically.
"Obviously, this won't work with an isolated power supply like the Voodoo Lab Pedal Power 2, since the isolated outputs prevent common grounds from forming. This is why that power supply has a 12 volt/ACA setting."

Are you using that 12V hole for something else?

MikeH

#6
December 03, 2015, 07:42:02 AM
Ahhhh... I understand now. I had always run the pedal using a daisy chain before both with a one spot and the pedal power, then moved it to its own slot on the pedal power and it started acting funky. And after that I tried it with the original one spot (and a handful of others) but never on a daisy chain again. Didn't realize I actually owned any of this style boss pedal. I guess I just got lucky all these years, lol.

Thanks for helping me sort it out!
"Sounds like a Fab Metal to me." -DougH

Ice-9

#7
December 03, 2015, 08:24:45 AM
Quote from: MikeH on December 03, 2015, 07:42:02 AM
Ahhhh... I understand now. I had always run the pedal using a daisy chain before both with a one spot and the pedal power, then moved it to its own slot on the pedal power and it started acting funky. And after that I tried it with the original one spot (and a handful of others) but never on a daisy chain again. Didn't realize I actually owned any of this style boss pedal. I guess I just got lucky all these years, lol.

Thanks for helping me sort it out!

It is a very simple mod to convert the pedal to use the standard power supply, I did not check the links above but I suspect one of them may be how to do the mod.
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

Please at least have 1 forum post before sending me a PM demanding something.

MikeH

#8
December 03, 2015, 01:46:52 PM
Well the pedal works with a daisy chain because the extra bs connected  to the ground on the DC Jack is effectively bypassed. so just running a wire from the negative terminal on the DC Jack to the ground in the pedal would do the same thing.
"Sounds like a Fab Metal to me." -DougH

alfafalfa

#9
December 04, 2015, 09:20:18 AM Last Edit: December 04, 2015, 10:32:51 AM by alfafalfa
Very helpful to know!

I have the same problem with an old Arion Stereo Delay which I bought recently.





And on this schem I don't see the zener diode anywhere !


I wil try the same trick ( stinkfoot's = bypassing a resistor and diode ) but now I noticed there's this tiny zener diode as well.

And the resisior in the schematic is not 330 ohm but 150 ohm in my case.

And what I am interested in is, will it still take the 12 volt?
The lowest electrolyte voltage reading on my pedal is 16 V ( near the powersupply, part of it I think) . The rest of the electrolytes all seem 50 V.

Has anybody tried this ? I would like to know before trying it myself and running the risk of ruining my pedal.

Alf
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