noise in Boss MT-2 pedal

[otokomae]

I'm getting a little too much noise coming from my friend's MT-2 pedal, and he's asked me to fix it.  I've done a lot of pedal modding, and built a couple from scratch, but I'm not really sure where to start looking for the source of this noise.  Can anybody give me any advice here?  I don't really know if the noise has always been there or not, but I know it's the same whether I use the effects loop or put it btwn the guitar and input, and it makes the noise in several different amps.  It's sort of a low hum, or just kind of a "white noise" that's very audible when you stop playing.  Is there any easy way to find out where it's coming from and cut back on some of the noise?  Thanks!!!

[Paul Marossy]

Does your guitar use single coil pickups?

[ninoman123]

Make sure you are using a very well filtered power supply. I built my own power supply once and didnt use any filtering on the AC line and had a terrible white noise like you described. At first I thought it was my amp but then it turned out that I needed a filter cap across the AC of my power supply. 1000uf or better will work. Check that out first.

[otokomae]

Oh yeah, I'm using a Washburn WI68 w/ humbucking pickups through a Fender Roc Pro head.  And I'm using a 9V battery (tried switching batteries already.)  I was plugging it in at first, but the power supply was my first thought, so I switched to 9V.  Is there somewhere in the pedal where I might want to put a filtering cap?  this is my first time tackling this problem.

[no one ever]

batteries can't hum

read it in an article. if there was a need for power filtering for 9v batteries, pedals would be much bigger. ever seen a 1000uf cap? yeah.

[MartyMart]

My guess is that there's nothing wrong with it, high gain = noise !
I bet when its set to a much lower gain and your pups are
hum cancelling, it will be fine.
Check also "cable runs" between gtr-pedal-amp, I had some awful
noise the other day, due to my cable running next to a 12v AC wallwart
cable  !

MM

[Paul Marossy]

My guess is that there's nothing wrong with it, high gain = noise !
I bet when its set to a much lower gain and your pups are
hum cancelling, it will be fine.

My thoughts, too.

Check also "cable runs" between gtr-pedal-amp, I had some awful
noise the other day, due to my cable running next to a 12v AC wallwart
cable  !

Sometimes a wah pedal will also pickup hum from a wall wart and drive you crazy when you use it and the Metal Zone together - you can't really hear it until you turn on the pedal, and then it amplifies the heck out of the hum! 

[R.G.]

if there was a need for power filtering for 9v batteries, pedals would be much bigger. ever seen a 1000uf cap? yeah.

1000uF caps aren't that big if you get low voltage ones. I've put 1000uF caps in pedals before in the leftover space. It's not that hard.

[Paul Marossy]

1000uF caps aren't that big if you get low voltage ones.

Yeah, a 16V 1000uF cap is only about 1/2" in diameter and about 3/4" tall...

[otokomae]

Thanks guys!  I've got practice tomorrow, so I'll see if I can sort this out.  One of my friends pointed out, also, that I might have just gotten used to my own homemade pedal, which is just as high-gain but SUPER quiet caompared to this thing ( and he says it's super quiet compared to any high-gain pedal he's ever played.)  So, yeah, it could be that this is just a noisier pedal, which I'd thought of, but I was hoping there was something I could do, like replacing some of the little ceramic caps w/ silver micas, or something like that, but I wasn't sure where to start...  when I open it up, this pedal is almost infinitely more complicated than the one I built!  Without a schem it's almost impossible to follow all the traces.  So yeah, I'll try checking where the cables run to see if it's picking up any outside noise, maybe I'll change out some of the caps, see if that does anything.  Thanks everybody!