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chrissydamage
Silver Member
United Kingdom
180 Posts |
 Posted - 10/23/2009 : 17:37:29
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Afternoon all,
Was wondering if someone can help me here-
Got a Metal Zone that appears to operate OK but its really really quiet- any ideas what this could be or where I should check?
Bypass is fine, but when the effect is on it reduces the volume by about 80%, all the dials work fine though. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/23/2009 : 18:08:18
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Hi chrissydamage
Just quickly before I head of to ZZzzz land (bed).
Other than some more difficult electronic fault.
First check for dirty input & output sockets/jacks.
carefully spray some contact cleaner on them.
or blow them out with a can of compressed air first.
I had a similar problem a few hours ago with a vintage CE-2 I was working on-testing.
The volume level dropped to almost inaudible levels.
The sockets seem to collect all the dirt & grit, from guitar cables dragged across dirty & gritty floors & stages, even just the fluff off a clean home carpet, can build up & become a partial insulator.
That's one reason I clean off all my leads after a gig,
I just run a clean cloth over their length, & occasionally wipe the ends with a cloth that has some contact clean sprayed on it.
Good luck, I hope it's not anything else major.
Regards Dr. Bob 
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chrissydamage
Silver Member
United Kingdom
180 Posts |
Posted - 10/23/2009 : 20:41:07
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Hi Dr Bob
Thanks for the tip- gave it a try but no joy unfortunately 
This is one of those nightmare pedals that has been apart and been back together many many times over the last 6 months.....
Original problem was it was totally dead-
First noticed loads of play in the input sockets and that it would switch if you wiggled the input jack around so I bent those back into place and cleaned them- then it switched ok, for a while....
Then I noticed similar play on the DC socket, so I fitted a new DC socket and now its switching perfectly, but just a total lack of volume when its switched on-
Its still totally possible its the jack I guess, but its got to the stage where I'm just throwing parts at it now.
I've located a wiring diagram for it so I may study that in the meantime :) |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/23/2009 : 21:20:49
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Hmmm... probably won't be the jack Dr.Bob because the bypass level is fine?
It might be the output buffer playing up. I'll have to have a look at the schem as well. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/24/2009 : 07:45:28
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quote:
Originally posted by Laurie
Hmmm... probably won't be the jack Dr.Bob because the bypass level is fine?
It might be the output buffer playing up. I'll have to have a look at the schem as well.
Hi Laurie, chrissydamage & guys
Yeah I thought that as well, after I already posted my very late night reply.
I know my way around this pedal a bit, if you recall,
I recently repaired hateandwar's MT-2 a few months back.
Check the opamp that controls the tone controls as well.
When you have it in bits, tie-wrap the white wire to the output socket.
It's connected to a single island PCB track pad.
much too small for reliability or a lot of movement when you have it in apart.
A dob of hot melt glue over the wire, & PCB on the component side is also a good idea.
I have one or two "really old Vintage SIP opamps" if you get caught with your pants down.
But like we both discovered a few months back.
Depending on the age of the MT-2?
There are at least (3) variations of the MT-2 & the op-amp selection Boss used in their production runs.
Regards Dr. Bob |
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chrissydamage
Silver Member
United Kingdom
180 Posts |
Posted - 10/24/2009 : 17:50:46
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Thanks for your help guys!!
Good idea about the output socket Dr Bob- I looked at it again and the white wire was only held in place by a single solitary strand of wire- so thats now resoldered but alas the problem remains the same....
I'm aware of the different metal zones, this is one of the proper ones from 1990 ;)
My wiring diagram doesn't actually appear to cross reference the componants with the location on the board so its of little use to me at this stage-
I was poking around on the interweb and found a comment somewhere that these have a problem with blowing capacitors-
I've checked all the capacitors and most of them seem to read approx 4-4.5V apart from:
C2, C3, C4 and C5
C11
C37 and C39
Which all read < 0.1V
Anyone got a decent schematic for one of these?
I think I'm almost nibbling on the heels of success here ;) |
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Laurie
Double Platinum Member
Canada
4854 Posts |
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chrissydamage
Silver Member
United Kingdom
180 Posts |
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chrissydamage
Silver Member
United Kingdom
180 Posts |
Posted - 10/26/2009 : 20:53:42
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Hmmmmmm......
After studying the schematic and the pedal and scratching my head for many hours it looks to me like the MT-2 has 4 ICs each split into 2 parts:
IC1 for the low and the high
IC2 for mid and mid Frequency
IC3 for the distortion
IC4 must surely be the output (buffer?)
The solder joints around IC-4 look quite 'dusty' certainly when compared to the other ICs, so hopefully thats the fault- I think its just the one thats gone down but I ordered a bunch of them anyway in case I need to do a set.
Thanks Dr.Bob and Laurie for your assistance, very much appreciated!!
I'm actually very intrigued by the design of this pedal, and I've decided that I'm going to get hold of another one purely for experimentation purposes 
Being very common and cheap, it seems like the perfect pedal for chopping around with, and it sounds pretty good as standard too-
Just looking at the schematic there seems to be much potential for 'refining' the design too- hours of fun to be had there definately :)
Or maybe I'll end up with 2 dead metal zones........ |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/26/2009 : 21:06:54
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quote:
Originally posted by chrissydamage
Hmmmmmm......
After studying the schematic and the pedal and scratching my head for many hours it looks to me like the MT-2 has 4 ICs each split into 2 parts:
IC1 for the low and the high
IC2 for mid and mid Frequency
IC3 for the distortion
IC4 must surely be the output (buffer?)
The solder joints around IC-4 look quite 'dusty' certainly when compared to the other ICs, so hopefully thats the fault- I think its just the one thats gone down but I ordered a bunch of them anyway in case I need to do a set.
Thanks Dr.Bob and Laurie for your assistance, very much appreciated!!
I'm actually very intrigued by the design of this pedal, and I've decided that I'm going to get hold of another one purely for experimentation purposes
Being very common and cheap, it seems like the perfect pedal for chopping around with, and it sounds pretty good as standard too-
Just looking at the schematic there seems to be much potential for 'refining' the design too- hours of fun to be had there definately :)
Or maybe I'll end up with 2 dead metal zones........
Yeah... my favorite pedal for modding:
http://members.shaw.ca/lauriepedals/Stormchaser.pdf
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 10/27/2009 : 14:54:08
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quote:
Originally posted by chrissydamage
IC4 must surely be the output (buffer?)
IC4 is used for post distortion amplification/filtering.
Most Boss pedals use transistor based buffers with a few exceptions (a version of OD-1). |
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Topic |
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Semi Functioning Metal Zone
