This article discusses how to troubleshoot power supply issues on your pedalboard.  It applies to any digital or high-current pedals.


  • a pedal is making a loud humming sound
  • a digital pedal is randomly turning itself on/off
  • a digital pedal works fine in practice, but shuts down during a gig
  • LED changes to magenta or pink and pedal switches to bypass (Red Panda pedals)

If our pedals detect a problem with the power supply, the bypass LED with change to magenta (or pink), the pedal will switch to bypass and enter a low power mode.  After a few seconds, the pedal will restart (in case it was a short power glitch).  In some cases, the LED will not change but the pedal will emit a hum or buzzing sound, even when it is in bypass.

Digital pedals typically use more current than analog pedals, and are much less forgiving of power issues.  Whereas analog pedals will have decreased headroom or start to distort when the voltage or current are too low, a digital pedal will fail in erratic ways.  The digital signal processor may crash, causing the pedal to either lock up or reboot itself.  If the power supply is not able to deliver enough current, the voltage may drop or it may cycle up and down as the power supply tries to recover.

Step 1: make sure each pedal is connected to an outlet with the correct power output

Every pedal specifies a voltage and minimum current.  It can usually be found on the web page and in the owner's manual.  For example:

    9V DC, center negative, minimum 250 mA

The pedal should be plugged in to an output with the same nominal voltage (9V) and direct or alternating current (DC in most cases).  Some pedals can operate at different voltages, for example, at 12V or 18V for higher headroom.  If your power supply has switches to select the output voltage, make sure they are set correctly.

The current specified by a pedal is the minimum current that the power output needs to be able to supply.  Higher numbers are fine - the pedal will only draw what it needs.  So a pedal that needs 250 mA will work on a 300 mA or 500 mA output (but not 100 mA).

Daisy chain cables share the current across every pedal that they are connected to.  Daisy chain examples are the True Tone 1 SPOT Slim, the Voodoo Labs Output Splitter Adapter, Boss TU-3 DC OUT jack, or any other daisy chain power cable.  Add up the current requirements for each pedal in the chain and make sure it is lower than the output's rated current.

Also check to make sure that you are not using mutually exclusive (either/or) outputs.  For example, on the T-Rex Fuel Tank Chameleon, outlets 5 and 6 may only be used one at a time.

Step 2: make sure the total current does not exceed the power supply's capacity

Some isolated power supplies share current across all outputs, or allow an output to "borrow" current from other outputs.  For example, the 1 SPOT Pro can deliver 300 mA from its 200 mA outputs.  In most cases it will not be explicitly stated, but the output may try to deliver more current if the pedal(s) need it.  Note that we do not recommend exceeding the labeled current of any single output, except in cases where the power supply manufacturer explicitly says it is ok.

Add up the current requirements for every pedal connected to the power supply.  Then add up the labeled current output for all of the power supply's outputs.  The sum of the pedal current requirements must be lower than the sum of the outputs' labeled current, preferably with a 10% margin.

Step 3: isolate the pedal that is having problems

Unplug all of the pedals from the power supply, except the one that is having problems.  Use a simple pedal chain like instrument-->pedal-->amp and see if the pedal functions normally.  If it does, add in other pedals one by one until the problem appears.  It could be one pedal using more power than normal, the total pedal chain stressing the power supply, or a noise issue from one pedal affecting another pedal.

Try using a different power supply.  We keep a Boss PSA-120S adapter handy for testing.  It is a simple, bulletproof adapter that can power just about any pedal.

Step 4: check for surprises

The Truetone 1 SPOT mA Meter is helpful to see how exactly how much current each pedal is drawing.  Some pedals use different amounts of current in different modes.

Contact us 

If you are still having issues, contact us and we will help you troubleshoot the problem and arrange a repair if needed.  Please let us know what troubleshooting steps you have tried and as much information about your setup as possible.  The make and model of your power supply along with a cell phone pic of your pedalboard is usually enough to get started.

See this article for information about using specific power supplies with Red Panda pedals.