Hi :) I have a problem with my Boss mt-2 pedal. Whenever I insert the jack plug in the input, the adapter switches off automatically. The pedal works fine with battery and no problem is created. This only occurs whenever the jack plug is inserted and the adapter is switched on thanks :)

DId you remove the plug from the input jack to turn the pedal off? If so then you may have a bad input jack.

The battery is connected via plugging in the input guitar cable ( a seperate contact is made at the jack). Sometimes this can be broken. Usually this failure is caused by someone stepping on or yanking a cable and the solder is broken at the jack/board attachment. This can be the input jack OR the power jack. Occasionally the circuit board or the traces on it are cracked, requiring jumpers to be installed on the board. In any case, open the pedal and look for these problems.

Are you using battery or AC adapter for power?
Most pedals won't allow you to use both. Check that there is no battery installed if you're going to plug it in. If you are using a battery, Some pedals won't light an LED on battery power.
If problem persists, your pedal may be DOA

The first thing I would do would try a 9V AC Adapter to rule out a battery issue completely. But if you have changed the battery already, this shouldn't be the issue. Does the red light come on at all? The next thing I would check involves removing the back cover of the pedal and making sure the input/output jacks are okay. Do you see any hanging wires, loose solder, or smell a burnt smell? If you have only had this pedal for a few months, you may be able to send it back to BOSS for replacement under your warranty.

Try the obvious stuff first.

1. Check that it has a battery in it and it is installed the right way round.
2. Only use top quality batteries (Duracell Ultra or equivalent) do not use re-chargeables as they don't achieve adequate voltage.
3. If you are using a mains adapter try a battery instead as the adapter may be faulty (or vice versa)
4. Some effects pedals will not switch on without a jack plug in either the input or output socket (or both)
5. If none of that works it is probably faulty - take it back to the shop and ask them to replace it or prove it works

use boss power supply

A few things to try....

Usually the adapter will over ride the battery when used.
1) Make sure your 1/4" cables are working properly without the pedal "in-line".

2) Take out battery, and use just the adapter only. Make sure it is the correct and proper adapter that works with Boss. Usually the PSA-120. If you are not using a Boss Adapter, make sure yours is a direct replacement with same specifications. 9V/200mA. And "tip negative". DO NOT use Radio Shack stuff, nothing against them, but there adapters just don't mix well with Boss products and the like.

2) Try just the battery, no AC adapter. Remember to unplug the input when not in use. Saves battery.

Basic rule of thumb...when using correct AC adapters for all your pedals all the time, and all sounds good, then take out the batteries.

If you still experience problems, it would be an internal IC chip most likely. From there post another question maybe.

Distortion is a very HIGH gain operation and any hum on the input will be amplified many times.

Check your guitar AND input cable for ANY hum at all at high gain settings on the amp WITHOUT the pedal in line to assure that the source is not before the pedal.

ADDITIONAL cause could be a poor power adapter for the pedal or even a bad filter cap in the pedal.

First and foremost , check your signal chain. By that, i mean put the pedal aside, ...just unhook it and take it out of your signal path. Using the same cables , guitar , amp, other pedals - borrow a friends MT-2 if you can get one , and try THAT to see if THAT works , OR any other kind of distortion pedal. If another one works ok , it's YOUR MT-2. Boss pedals are pretty rugged , but sometimes the little actuator (on/off switch) underneath the treadle (where you push your foot down) will become faulty. That's a high-gain pedal - are you using a basic Strat or other single-coil pickup guitar? If so , are you playing close to any flourescent lights? SIngle coils are noisy around those lights. Will cause a hum / buzz if using a heavy dist. pedal. You can check that by moving around as you play.

Try changing the battery, if it doesn't help, some possibilities are:

- dirty contacts or a broken wire on the footswitch

- a broken wire from the distortion output to the output plug

- a broken wire elsewhere in the unit (e.g. potentiometers or rotary controllers)

- a bad input / output level or other potentiometer or rotary controller

- a burnt out component (a bit unlikely, but possible, and it could be anything)

- a bad connector contact inside the unit

- a bad pin solder contact on ANY of the components inside the unit (wires, connectors, switches, jack plugs, resistors,variable resistors, trimmers, diodes, capacitors, transistors, ICs, etc.)

Broken wires / badly soldered pins need to be resoldered, but if there is damage to any of the components, they wil probably need to be replaced.

I hope you can find out what it is.

regards

3rq8 (Triarcuate)