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MXR phase 90 issue


apocalyptickaoss
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On the advice of this board and others, I bought a second hand phase 90 on Gumtree for 50 quid. Great deal. However, today, I plug it in, and find that, while it works, it causes a whole lot of popping and crackle. It seems to distort chords if you play them to hard, and single notes seem t have a really nasty "popping attack, whenever you use a pick. Any ideas what the problem could be?

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At a guess, without having a proper listen/look at it, it could be a number of issues, such as the jacks, the power filtering section etc etc.

 

Philllll's suggestion to try it with just a battery, not via the powersupply would actually help with figuring out what the problem might be.

 

Try just running Guitar > Phase90 (powered by battery) > fairly clean setting on amp and let us know what happens then.

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At a guess, without having a proper listen/look at it, it could be a number of issues, such as the jacks, the power filtering section etc etc.

 

Philllll's suggestion to try it with just a battery, not via the powersupply would actually help with figuring out what the problem might be.

 

Try just running Guitar > Phase90 (powered by battery) > fairly clean setting on amp and let us know what happens then.

 

Oh right, Sorry :p

 

Bypassed on my laney vc30, completely clean with no breakup at all. THe reason I bought the amp.

 

P90 engaged, kinda crackly distortion going on with chords, and the popping I talked about. New battery.

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Hmmmm.... I'm trying to rack my brains with this. I'm 99.9% sure I've heard of this problem before, on another message board I'm part of.

 

I have a funny feeling that it's something like a bad diode or a bad capacitor or something like that, but I can't quite remember exactly. I'll see if i can find it though.

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ok, so just a couple of little diagnostic things to check. Just trying to eliminate variables really. For all of these, it should just be guitar > pedal > amp. Power brick or not shouldn't matter.

 

1. Without playing anything put the pedal in bypass (ie, effect off) and see if you get any crackle noise. You should also check if you get any crackle at this stage from the jacks. Do this by giving the cable a little wiggle where it goes into the pedal.

 

2. Do the thing with the wiggling the jack but when the effect is engaged, and when you're playing nothing.

 

3. If you turn your guitar's volume down (try it at a range from low > high) do you get the same crackly popping distortion effect?

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ok, so just a couple of little diagnostic things to check. Just trying to eliminate variables really. For all of these, it should just be guitar > pedal > amp. Power brick or not shouldn't matter.

 

1. Without playing anything put the pedal in bypass (ie, effect off) and see if you get any crackle noise. You should also check if you get any crackle at this stage from the jacks. Do this by giving the cable a little wiggle where it goes into the pedal.

 

2. Do the thing with the wiggling the jack but when the effect is engaged, and when you're playing nothing.

 

3. If you turn your guitar's volume down (try it at a range from low > high) do you get the same crackly popping distortion effect?

 

1. No Crackling

 

2. No crackling

 

3. It's only near the upper range of the guitar's volume that you get the overdrive/distrotion.

 

I think I wasn't very clear when I said crackling, sorry about that. I meant the distortion that it causes, which sounds very crackly, not that there's background noise. Sorry!

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Well, it's not the jacks. I'm just trying to think of things it could be without having to investigate the actual effect circuit itself. I'm taking that as a last resort ;)

 

It actually sounds like a short somewhere. I've heard of this happening when certain Phase90 mods aren't done properly, but it can also happen if the board inside the box comes a bit loose. Try disconnecting everything from it, undo the 4 screws underneath the pedal, and check to make sure the PCB isn't loose. If any of the solder joints end up touching off the metal case, it can short something, which can result in things like cracking, screeching, and various other unpleasantries!

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Well, it's not the jacks. I'm just trying to think of things it could be without having to investigate the actual effect circuit itself. I'm taking that as a last resort ;)

 

It actually sounds like a short somewhere. I've heard of this happening when certain Phase90 mods aren't done properly, but it can also happen if the board inside the box comes a bit loose. Try disconnecting everything from it, undo the 4 screws underneath the pedal, and check to make sure the PCB isn't loose. If any of the solder joints end up touching off the metal case, it can short something, which can result in things like cracking, screeching, and various other unpleasantries!

 

Nope, board is still tightly in place :)

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UPDATE: as it turns out, it was normal to get the horrid midrange distortion I was hearing. Cut a long story short, I did the "R28 mod", along with C11 and C12. After spending 5 minutes feeling ridiculously nervous and feeling like a fucking bomb disposal expert, I am pleased to report that although it has lost the boost in volume, the distortion has gone and it is now destined to become a staple of my pedalboard <3

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