MXR M239 Mini Iso-Brick Power Supply

The long story.

The Mini Iso-Brick Power Supply supplies quiet, noise-free DC power to wide range of pedal types while taking up less space than a candy bar. Whether you need a space-saving solution for your downsized travel board or you just need to power a small, carefully curated selection of tried-and-true staples, this little box has what you need.

First, let’s talk outputs. The Mini Iso-Brick Power Supply has five, and each is fully isolated to eliminate obnoxious, gig-ending ground loop noise. Four of the outputs supply 9 volts of power at 300mA, while a fifth can be set to provide either 9 volts or 18 volts at 800mA depending on your needs. With a generous amount of current on tap and the ability to handle both negative and positive grounds, these outputs will accommodate almost any pedal, analog or digital.

And don’t let the five outputs restrict you—if you need to add an extra pedal, the Mini Iso-Brick Power Supply has you covered. It comes with a splitter cable that can be used to connect two pedals to a single output, provided they require the same voltage and you don’t exceed the output’s current rating. You can do this with all of the outputs simultaneously—just purchase the extra cables to do so.

Finally, troubleshooting can be a hassle on dark stages, so the Mini Iso-Brick Power Supply comes equipped with LEDs to let you know that all your connections are solid. Combine that with a lightweight housing that's built like a tank, and you can step on stage with confidence that your pedalboard will stay powered from gig to gig.

The Mini Iso-Brick Power Supply supplies quiet, noise-free DC power to wide range of pedal types while taking up less space than a candy bar. Each of its 5 outputs is fully isolated, eliminating gig-ending ground loop noise. Whether analog or digital, positive or negative ground, this little power box has you covered.

Power

The Mini Iso-Brick Power Supply requires an 18V regulated power supply rated at 2000 mA, with 5.5mm x 2.1mm positive barrel, negative center plug. The included power adapter can utilize a wide range of wall power, from 100–240V at 47–63Hz. Comes with switchable US/Japan, UK, EU, and Australian plugs

Operation

• Connect included AC adapter into M239’s 18V INPUT jack.
• Plug AC adapter into wall outlet; white INPUT LED indicates good connection.
• Connect up to four pedals requiring 9V power to the four 9V OUT jacks using the included barrel-to-barrel cables.
• Connect another pedal to the switchable 9V/18V output. Use 9V/18V slide switch to match pedal voltage (indicated by green LED).
• Splitter cable can be used to connect two pedals to a single output. Connect straight end to M239 output and rightangle ends to pedals’ power inputs.
• Whether connecting single pedal or multiple pedals via splitter cable, always be sure pedal mA ratings do not exceed output mA ratings.

Troubleshooting

• The power LED fails to light.
• Dead AC outlet. Try plugging into another outlet, or test the outlet with another device like a lamp.
• Faulty connection. Double check plugs to make sure they are inserted securely.
• Short-circuited output. Disconnect the cable from the output whose blue LED is off.
• Wait 5 to 10 seconds for the unit to reset, indicated when the blue LED comes on.

Power provided to some effects, but not others.

• Incompatible power plug. Check that the dimensions and polarity of the pedals are compatible with the provided cables.
• Faulty cord. Check by swapping the power cable with another known good cable.
• Faulty jack on Iso-Brick Power Supply DC output jack. Check by plugging the power cable into a different DC jack.
• Faulty jack on the pedal. Test by running the pedal off battery power.