Author Topic: Boss MT-2 Metal Zone Schematic  (Read 7381 times)

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nickbungus

Boss MT-2 Metal Zone Schematic
« on: September 26, 2016, 10:20:16 AM »
Hi All.  I am currently in the process of copying the Boss Metal Zone Schematic into DesignSpark and then I plan on making my own pcb layout.  I've got another thread on here where I used a layout from the internet but it had a few problems and also I plan on making 2 differences:
  • Remove the switching and modify for true bypass
  • Introduce a noise gate as it can been a noisy beast

Can anyone please advise on what I should be omitting to remove the switching and any buffer so I can use true bypass?

Heres the schematic:


No, they are not jumpers, they are just very, very low value resistors.

anotherjim

Re: Boss MT-2 Metal Zone Schematic
« Reply #1 on: September 26, 2016, 11:05:31 AM »

I think that's it Nick.
The output buffer probably can go too. So connect from the level pot wiper as far as that 10uF output cap (C001?).

"So lets stay within the limit of sureness: lets consider the fuses you have available and lets see what you have to do to light them up..." Farfisa Partner 15 drum machine manual.

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #2 on: September 26, 2016, 11:14:55 AM »
Brilliant Jim, thanks as always.  Once I've finished the redrawn schematic, I'll upload it before I get cracking on the layout.
No, they are not jumpers, they are just very, very low value resistors.

bloxstompboxes

Re: Boss MT-2 Metal Zone Schematic
« Reply #3 on: September 26, 2016, 11:28:20 AM »


Sorry, those borders always irritate the crap out of me. Looks much simpler with all that stuff out of the way.

botophucket.com screwed up the clarirty of my original upload.
« Last Edit: September 27, 2016, 11:22:32 AM by bloxstompboxes »

Floor-mat at the front entrance to my former place of employment. Oh... the irony.

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #4 on: September 26, 2016, 11:58:12 AM »
Thanks Eric.  Yes those border things are highly annoying and takes something away from the clarity.
No, they are not jumpers, they are just very, very low value resistors.

Elijah-Baley

Re: Boss MT-2 Metal Zone Schematic
« Reply #5 on: September 26, 2016, 12:54:00 PM »
Consider the possibility to introduce some mods. I modded my MT-2 stock using the Deizel mod, and though I have a cheap solid state amp, now I can use the pedal without feeling bad. ;D
«There is something even higher than the justice which you have been filled with. There is a human impulse known as mercy, a human act known as forgiveness.»
Elijah Baley in Isaac Asimov's The Cave Of Steel

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #6 on: September 26, 2016, 01:56:44 PM »
I just had a read of this.

The mods on there are either swaps or removals.
No, they are not jumpers, they are just very, very low value resistors.

Elijah-Baley

Re: Boss MT-2 Metal Zone Schematic
« Reply #7 on: September 26, 2016, 04:16:36 PM »
Well, that mods (and also the Bogner mod, it is pretty similar) is an ensemble of modifications.
If you don't have problem of space you can fill the pedal of switches, but I don't know how much sense has this. Every mod changes a bit the sound, and all together change more, perhaps not change a lot, but change enough in my opinion.
A consideration:  testing the mods in a pedal after an interval of some minutes make hard to notice much difference. Anyway, I tested the sound of the pedal after every step, and I can say I could hear the difference of the sound after the whole "These three mods remove the harshness somewhat" (See the link of the previous post).
C35: remove
C34: 0.047uF MKT Capacitor
C25: remove

And after the diodes mod I noticed the difference.

You could keep the original clipping diodes, them have still a kind of harshness and compression, and to use a switch to pass to the other clipping (D3: Red LED; D4: 1n4001), those make the sound rounder, fuller and dynamic.

For the other mods I suggest you to make some tests and to choose the best components and the best result to your ear. I don't see the reason to choose between two sound, one bad and one better.
I prefer the MT-2 after the mod, and I will never want a switch to remove the mod.

I wish I helped you. ;)
«There is something even higher than the justice which you have been filled with. There is a human impulse known as mercy, a human act known as forgiveness.»
Elijah Baley in Isaac Asimov's The Cave Of Steel

greaser_au

Re: Boss MT-2 Metal Zone Schematic
« Reply #8 on: September 26, 2016, 06:34:35 PM »
Thanks Eric.  Yes those border things are highly annoying and takes something away from the clarity.

Bear in mind that the schematic we are looking at here is from the SERVICE manual for this particular manufacturer's product (not a clone/workalike).  This product has 3 PCBs; the borders are an aid to make it clear to the service tech (who may not have seen an MT-2 before) where the various bits of the circuit physically live, which will save him/her bench time, and thus (more important), reduce the cost of a repair to the client*...  Admittedly, this is a fairly simple circuit, and any tech worth his salt would not really need this kind of breakdown - but conversely these border markings are unlikely to cause that same tech any confusion,

Speaking (typing? :) )  as one who has had to earn a crust fixing electronics quickly and efficiently, I have to say that a nice service manual (like this range of pedals has) is a godsend (and I have seen some TERRIBLE manuals** in my time)...  :)

* this ignores the present economics of repairs, but when these were new, they were fairly expensive, and labour costs were much lower than now...
** and this is getting worse because of the economics of repairs...

david

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #9 on: September 27, 2016, 02:06:09 AM »
What I meant was I am grateful for Eric's help and for my purposes the borders are annoying and it's much clearer with them removed.

I totally understand why they are there and who the schematic is aimed at.   
No, they are not jumpers, they are just very, very low value resistors.

bloxstompboxes

Re: Boss MT-2 Metal Zone Schematic
« Reply #10 on: September 27, 2016, 11:23:28 AM »
Updated my original post since botophucket screwed up the clarity of my first schem pic. Now it is much clearer.

Floor-mat at the front entrance to my former place of employment. Oh... the irony.

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #11 on: October 04, 2016, 07:21:53 AM »
Anyone wanting to cast a beady eye over this before I start my layout, I would be more than grateful?  Thanks :) 

No, they are not jumpers, they are just very, very low value resistors.

anotherjim

Re: Boss MT-2 Metal Zone Schematic
« Reply #12 on: October 04, 2016, 01:43:33 PM »
I haven't ticked it off part for part, but I don't see any loose ends or wrong polarities.
"So lets stay within the limit of sureness: lets consider the fuses you have available and lets see what you have to do to light them up..." Farfisa Partner 15 drum machine manual.

Chugs

Re: Boss MT-2 Metal Zone Schematic
« Reply #13 on: October 04, 2016, 01:51:48 PM »
You are missing a 0.047uf cap connecting to the positive input on U01b.

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #14 on: October 04, 2016, 04:51:01 PM »
Thanks Jim and Chugs.

Chugs - Great Spot!  I went through it marking everything off but that one got through the net.  I know it was a bit of a cheeky ask but its much appreciate having a second set of eyes!
No, they are not jumpers, they are just very, very low value resistors.

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #15 on: October 16, 2016, 12:54:35 PM »
I've been battling away at this on my lunch breaks at work and have a layout that fits into a 1590b.  Might have to choose my pots wisely to squeeze it all in but think it can be done.

While I have been making this I've done a bit of reading and Youtubing and its such an interesting pedal.  Hated by so many but I had one and really regret selling it.  I'd never gigged with it but its brilliant for bedroom metal.  Some of the mods seem to make it a bit more friendly for gigging etc but I plan to make one as a 100% replica (albeit with the switching removed) and then make some more experimenting with the mods.

No, they are not jumpers, they are just very, very low value resistors.

bloxstompboxes

Re: Boss MT-2 Metal Zone Schematic
« Reply #16 on: October 16, 2016, 05:10:28 PM »
I'd appreciate, and I think everyone else would too, if you would post the layout and BOM once verified. Of course, you don't have to, but we would like it, lol.

Floor-mat at the front entrance to my former place of employment. Oh... the irony.

nickbungus

Re: Boss MT-2 Metal Zone Schematic
« Reply #17 on: October 16, 2016, 05:19:54 PM »
Sorry Eric.   I should have said.   I always intend on sharing 100%.  I just don't want anyone wasting their time if I've made a silly mistake somewhere.  Once built and working expect all files,  layouts etc.

Anyone know what the analog man mods are?
No, they are not jumpers, they are just very, very low value resistors.

bloxstompboxes

Re: Boss MT-2 Metal Zone Schematic
« Reply #18 on: October 16, 2016, 05:32:02 PM »
Sorry Eric.   I should have said.   I always intend on sharing 100%.  I just don't want anyone wasting their time if I've made a silly mistake somewhere.  Once built and working expect all files,  layouts etc.

Anyone know what the analog man mods are?

Sorry, didn't mean to imply you weren't. Just been interested in making one of my own. Of course, you want to verify before people waste their time with it if there's a mistake. Got an issue with my 6 0DD FOxes chorus myself and been meaning to get back to it. Looking forward to the results.

Floor-mat at the front entrance to my former place of employment. Oh... the irony.

ElectricDruid

Re: Boss MT-2 Metal Zone Schematic
« Reply #19 on: October 18, 2016, 11:12:43 PM »
One thing I found odd about the Metal Zone is that unity-gain inverting op-amp after the gain stage and clipping diodes - U04a on your schematic. It doesn't actually do anything. I can only assume that either they were concerned about the pedal being inverting or they had an op-amp left over (or both, I guess). It'd be seven op-amps without it, which isn't a particularly convenient number.

Tom

Edit: 04a not 04b
« Last Edit: October 19, 2016, 06:14:07 AM by ElectricDruid »