Mini Iso-Brick M239 - Effect pedal MXR - Free user manual and instructions

Brand	MXR
Model	Mini Iso-Brick M239
Product Type	Isolated Power Supply for Effects Pedals
Input Voltage	18V DC (via included AC adapter: 100-240V AC, 47-63Hz)
Input Current	2000mA
Input Connector	5.5mm x 2.1mm barrel, center negative
Number of Isolated Outputs	5
Outputs Detail	4 x 9V DC @ 300mA each; 1 x switchable 9V/18V DC @ 800mA
Total Power Output	17.1W (all outputs simultaneously)
Polarity	Center negative for all outputs
Output Connector Type	5.5mm x 2.1mm barrel
Isolation	Full isolation between outputs to eliminate ground loop noise
Protection Features	Foldback current limiting (FBCL), short circuit, overload
LED Indicators	White LED (input power), Green LEDs (output status)
Dimensions (Approx.)	115mm x 65mm x 38mm (4.5" x 2.6" x 1.5")
Weight (Approx.)	200g (0.44 lbs)
Included Accessories	AC adapter with US/Japan, UK, EU, AU plugs; set of barrel cables; splitter cable
Compatibility	Works with most 9V and 18V pedals, analog or digital, positive or negative ground
Construction	Compact metal chassis, designed for pedalboard mounting
Maintenance	Clean with dry cloth; avoid moisture; unplug when not in use
Safety Warnings	Use only supplied adapter; do not exceed voltage ratings of pedals

Frequently Asked Questions - Mini Iso-Brick M239 MXR

Can I power digital and analog pedals from the same Mini Iso-Brick?

Yes, the fully isolated outputs prevent ground loop noise, so you can safely mix digital and analog pedals, positive or negative ground.

How do I switch the variable output between 9V and 18V?

Use the 9V/18V slide switch on the unit. A green LED indicates the selected voltage. Ensure your pedal can handle the chosen voltage.

What is the maximum current draw per output?

Each of the four 9V outputs provides up to 300mA. The switchable output provides up to 800mA at either 9V or 18V.

Can I use a splitter cable to power two pedals from one output?

Yes, the included splitter cable allows sharing one output with two pedals, but ensure the total current draw does not exceed the output's rating (e.g., max 300mA for 9V outputs).

What do the LEDs indicate?

The white LED near the input lights when power is connected. Each output has a green LED that lights when that output is delivering power normally. If an LED turns off, there may be a short or overload.

What happens if I short-circuit an output?

The foldback current limiting (FBCL) circuit protects the unit. The affected output's green LED will turn off. Disconnect the faulty cable; after 5-10 seconds the output will reset.

Can I power a 9V pedal from the 18V output?

No, doing so may damage the pedal. Always match the voltage to the manufacturer's requirement. The switchable output defaults to 9V; only switch to 18V if the pedal specifically requires it.

Is the Mini Iso-Brick compatible with international voltages?

Yes, the included AC adapter accepts 100-240V AC, 47-63Hz, and comes with interchangeable plugs for US/Japan, UK, EU, and Australia.

Why is an output's green LED not lighting?

This could indicate a short circuit or overload on that output. Unplug the cable from that output; if the LED turns back on, the cable or pedal may be faulty. Also check for secure connections.

Can I mount the Mini Iso-Brick under a pedalboard?

Yes, its compact size (4.5" x 2.6" x 1.5") and metal chassis make it suitable for mounting with Velcro or screws (not included). Ensure ventilation holes are not obstructed.

USER MANUAL Mini Iso-Brick M239 MXR

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.

External Controls

1 WHITE LED indicates good input power connection
2 Four 9V DC outputs
3 One switchable 9V/18V DC output
4 9V/18V switch sets voltage output level of 9V/18V output (indicated by green LED)
5 INPUT jack 18V @ 2000mA power
6 GREEN LEDs indicate good output power connection

Basic Operation

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).

Included splitter cable can be used to connect two pedals to a single output. Connect straight end to M239 output and right-angle 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.

WARNING: Some pedals may be damaged if powered using voltage that exceeds level required by the manufacturer, e.g. powering a 9V pedal with 18V. We highly recommend staying at or below manufacturer's stated voltage requirement. Dunlop assumes no responsibility or liability for equipment damage caused by misuse of M239.

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.

Basic Operation

Connection Notes

Included cables use industry standard 5.5mm x 2.1mm positive barrel, negative center polarity plugs.

Each output features a green LED. When lit, this LED indicates a good connection. If short-circuited or overloaded, this LED will turn off.

M239's four 9V outputs can handle up to 300mA each.

M239's 9V/18V output can handle up to 800mA.

All outputs may be used simultaneously for a total power output of 17.1 watts.

The M239's foldback current limiting circuit (FBCL) provides ultimate protection against power shorts and overloads. Even at full load, the M239 operates coolly and quietly as a fully regulated power supply.

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.

Specifications

Input 18V At 2 Amps regulated supply (positive barrel negative center5.5mm x 2.1mm plug)

Outputs 9-18V @ 800mA (switched)

(4) 9V @ 300 mA

(all positive barrel negative center 5.5mm x 2.1mm)

*Note: Using a split cable allows you to share one output with two devices. Remember the straight plug is the end that goes into the Mini Brick DC output and the two 90° to the effects (this helps minimize ground return current noise), position.