Boss Metal Zone - No clean tone!

[Sub-Zero]

Hi there!
I am new here, but have been playing guitar for many years, and have a bit of an odd problem with one of my pedals.
The Boss MT2 Metal Zone, has no clean tone!

This is a new development with the pedal.
If I plug it in, and play, there is absolutely no tone when the led is not lit.
When I stomp it, activating the distortion, the sound comes through as it should, with a nice chunky distortion, and all variables work, with regards to tone, bass, level and distortion etc.
As soon as I stomp it again, to deactivate the distortion effect, there is complete silence, other than the twang of an unplugged electric guitar.

Does anyone have any ideas as to what I can do to fix this?
I would understand if it was the oterh way around, and the clean tone worked, but the distortion effect was not working.... but this is odd!


Now, over and above this, my very first pedal, of which I am very fond, due to it's backward wiring **(Factory error!!), an Ibanez Sound Tank Powerlead pedal, the switch has become a little iffy ... and requires multiple attempts to keep the effect on.
Is there any particular switch I can use for the pedal?

**

Incidentally, the pedal came with the incorrect value resistor or something, because when I crank the tone to increase treble, the pedal increases the bass value exponentially, giving the most amazing chunky bottom ends!
A friend had the same pedal as me, but his was wired correctly, so when he cranked the tone, his treble value increased, as did all other Powerlead pedals I tried in stores..... so I am pretty keen to get this one fixed!

Thanks for the help!!

[52 Bill]

Welcome to the place.

If I plug it in, and play, there is absolutely no tone when the led is not lit.
When I stomp it, activating the distortion, the sound comes through as it should, with a nice chunky distortion, and all variables work, with regards to tone, bass, level and distortion etc.
As soon as I stomp it again, to deactivate the distortion effect, there is complete silence, other than the twang of an unplugged electric guitar.

Does anyone have any ideas as to what I can do to fix this?

All Boss pedals use a buffered bypass and fet transistors as switching elements. So, it sounds like one of the fet transistors has gone bad. The one that sends the clean signal to the output.

What sorts of electronics and soldering skill do you have?

[Enzo]

Nothing strange about it, the pedal has two audio paths through it, the clean and the distorted. One of your paths has had a failure. In your case it happens to be the clean one.

[Sub-Zero]

Welcome to the place.


All Boss pedals use a buffered bypass and fet transistors as switching elements. So, it sounds like one of the fet transistors has gone bad. The one that sends the clean signal to the output.

What sorts of electronics and soldering skill do you have?

My skills are average at best..... I have a soldering iron, and I can get some solder..... as for the components required to fix it.... well, that's another story.
I will have to source an electronics shop.

Thank you for the insight..... It is great having people answer questions so quickly!

[Sub-Zero]

Nothing strange about it, the pedal has two audio paths through it, the clean and the distorted. One of your paths has had a failure. In your case it happens to be the clean one.

Hey Enzo

I was under the impression that companies would take the easy road, and have a simple, straight through passage for the clean tone, and the switch would be a more analogue based unit, bypassing the simple clean tone to distorted.

Thanks for clearing that up.
II am not particularly good with electronics..... but I love the sound difference they make to my guitar!!

[Mick Bailey]

With Boss pedals all is not what it seems - they aren't true-bypass so in clean mode there are still components involved with the signal path. As per previous replies, it's not just a mechanical switch that's involved. It's all still analogue, thought the switching circuit can be regarded as a primitive digital configuration. It's a little more difficult to troubleshoot and you need a multimeter and reasonable soldering skills. You also need to know what you're looking at inside the pedal.

Schematic here;

[Sub-Zero]

Thanks Mick.

In all honesty, I am in such a bad place at the moment, with regards to all my gear, I will most likely sell the pedal for scrap, and buy a multi effects pedal.
I recently moved from South Africa, where I had a Vintage ELK 60 Watt Bass Amp (Head and Cabinet with 4 speakers), and a Starfield VT-100 Valve amp by Ibanez.
I had a Boss FV pedal, with dual output, which I split between the two amps. The Starfield gave me amazing mid levels and high end, while the Elk threw out some gut wrenching bottom end chops. All with a crisp tone.

I used the Metal Zone pedal for distortion, and an Aria Chorus/Flanger/Phaser pedal.
I had my hybrid Powerlead pedal, and another chorus pedal, in case I wanted to flange or phase with the Aria.

Ariving in Adelaide, I purchased an acoustic Fender, and a cheap Epiphone Les Paul, which kept me happy until my baby arrived from Cape Town.
Finally, my Jackson King V arrives, and it has been dropped, while being tested at customs!
Headstock is slightly broken, and there are hairline cracks on the body, where the neck is bolted to the body!

The guitar is 22 or 23 years old, and cannot be replaced.
The Boss Metal Zone pedal is suddenly not working, and the Powerlead pedal switch is farked.
To top it all off, I was unable to bring over either of my amps, due to their weight and size.

So bleak right now!!

Please bear in mind, that I am 42 years old, and still into music like Ozzy, Metallica, Skid Row and the old GnR etc.

My set up, by today's standards, is probably absolute poo, but it produced the sound I loved, and I will not easily be able to replicate it.

Aaaaarrgggh!!!

Ok.... rant over!!

Thanks for listening!

[Justin Thomas]

My set up, by today's standards, is probably absolute poo, but it produced the sound I loved, and I will not easily be able to replicate it.!

And that is the ONLY standard that matters - it made the sound you loved. Don't "poo"poo it! In sonic art, cosmetics are nothing. Our rigs probably look quite similar...

Justin

[J M Fahey]

Pity you can't repair it because clean sound path *is* as straightforward and simple as can be in an electronic switch pedal:
1 resistor : R055
1 transistor : Q004
1 capacitor: C003
1 FET: Q003

and there's 50% possibility that there are no "bad parts" , but cracked track or solder.

there are other elements involved, but since they are shared with the dirty channel and it works, they have a clean bill of health.

In fact, the guy buying it from you will be immensely happy posting here for help, repairing it, and bragging "I bought it for $10 and spent $1 repairing it".

The real problem is that Techs generally don't repair stuff which can be replaced for $60 or less because that's about the minimum fee so customers balk at it.

[Enzo]

Exactly^^^

You hand me your pedal, and I am going to charge you at least $30 labor, more like $45-60. Parts will be nothing, $5 tops. There is nothing expensive in these things.

You do it yourself, and you are out only some time and maybe a little bit for a part.

[J M Fahey]

Dear


IF you feel confident enough to identify some parts (where is a certain transistor ) and follow tracks or wires (mmmmhhhh , it starts "here" turns right "there" , then left again and reaches ... oh , I got it) we might help you test at least some of the switching area functionality.

All you need is good light, good eyes (+2 to +4 $10 reading glasses help a lot) and a little [patience, plus a soldering iron and a 6 inch piece of wire, with both ends twisted and pretinned , and we may suggest you a couple simple tests.

A multimeter with a 20V scale also helps.

If you dare ....

[Sub-Zero]

And that is the ONLY standard that matters - it made the sound you loved. Don't "poo"poo it! In sonic art, cosmetics are nothing. Our rigs probably look quite similar...

Justin

Thanks Justin

That means quite a lot.
I am a member and a moderator on two other (non music) forums, and it's quite sad how some people (obviously egomaniacs), are quick to shoot down and ridicule anyone with a lesser set up than theirs.

Perhaps I will take the time to source the components and give it a go.

Thanks again!

[Sub-Zero]

Pity you can't repair it because clean sound path *is* as straightforward and simple as can be in an electronic switch pedal:
1 resistor : R055
1 transistor : Q004
1 capacitor: C003
1 FET: Q003

and there's 50% possibility that there are no "bad parts" , but cracked track or solder.

there are other elements involved, but since they are shared with the dirty channel and it works, they have a clean bill of health.

In fact, the guy buying it from you will be immensely happy posting here for help, repairing it, and bragging "I bought it for $10 and spent $1 repairing it".

The real problem is that Techs generally don't repair stuff which can be replaced for $60 or less because that's about the minimum fee so customers balk at it.

Thanks Juan.
I am pretty confident that there are no bad parts.... well, at least I hope hope not!
I will look into repairing it..... but it is high time I looked at getting something along the lines of a compact multi effects pedal.
They are getting quite incredible, with amazing sounds, all crammed into a small unit.

Will see what happens!

Dear


IF you feel confident enough to identify some parts (where is a certain transistor ) and follow tracks or wires (mmmmhhhh , it starts "here" turns right "there" , then left again and reaches ... oh , I got it) we might help you test at least some of the switching area functionality.

All you need is good light, good eyes (+2 to +4 $10 reading glasses help a lot) and a little [patience, plus a soldering iron and a 6 inch piece of wire, with both ends twisted and pretinned , and we may suggest you a couple simple tests.

A multimeter with a 20V scale also helps.

If you dare ....

I had a multimeter back in Cape Town, which I opted not to bring over.... you know..... why would I ever need one? Right? LOL!!
Good light is no problem.... eyes.... well, not so great these days. I am far sighted, so when I play paintball, I can see the guys hiding long before they know it...... but when it comes to finicky things like electronics etc. I will struggle a bit.
Will have to pick up a set of glasses for this job!

Patience: I have a 9 year old son..... I am pretty patient!
He would say otherwise!

Anyhow.... thank you all for your amazing support!
I will give it a go, and see what happens.
If all else fails, my four pedals can easily be traded up to a $100 multi effects unit.
They are all over the place here on the cheap.

Right now.... it's time to play some guitar!!

[J M Fahey]

Troubleshooting what I suspect is relatively straightforward: I suspect point "a" and point "b" are not properly connected (say one end of a capacitor to one leg of a transistor) although they "seem" to be connected by a printed circuit copper track.

So you simply solder the piece of wire from point a to point b and test the pedal.
No change? ... keep testing.
Sound restored?
Go buy a bottle of champagne, a sixpack, whatever

Or maybe switching signal is not reaching the switching FET ... similar test.

Or the switching FET is bad and stays open (or its solder is cracked : you bypass it with the piece of wire.

I'm used to repairing stuff on Tour, no Tools , besides a worn tip soldering iron, cheap solder and a $10 multimeter (if available) with a flat battery.

And *many* around here have also been in a similar situation, one time or another.

[Mick Bailey]

A good and easy way to trace a signal through your pedal would be to make up an 'audio probe'. Just a capacitor soldered to the end of a cable that's plugged into your amp and a grounding wire. The idea is you open up your pedal to get to the component side of the board and feed a signal to the input of the pedal. Then you can listen to where the signal gets to using the probe.

Despite having to hand a fair selection of measuring equipment, I often prefer this method, especially with pedals. It's often quicker to listen and probe, rather than keep glancing at a scope or meter.

There's another test method called the 'disturbance test'. You plug the pedal in as usual, but turn your guitar right down to zero and the amp on low volume. You touch a metal object such as a paper clip or piece of uninsulated wire onto key points along the circuit board. The amp buzzes like touching the tip of you guitar cable when there's a signal path. If you start from the output socket you can work backwards until the buzz stops. You've then found the problem area.