Phase 90 Problems

[aziltz]

I've got an unmodified, stock Phase 90, newer block logo. 

It seems that the sound no longer sweeps when the rate is below noon, but does above noon.  I haven't changed anything inside, but I can't figure out what would cause this.  Completely stopped <12, but normal sound >12

um, help?

[Sir_Ian]

Ok, first off, I don't have a phase 90, but I have built two phase 45's....and they are sort of similar. What I realized is that a 500k pot is specified. But I get very little phased at less than 12 o clock too. With 500k resistance the sweep is SUPER long. I think it would be better served with a 250k pot. But I left my 500k pot in for 3 reasons. 1) laziness. 2) I wanted it stock(basically laziness again) and 3) I have found a few uses for a very long sweep....

So my first thinking is that your phase 90 is sweeping but its such a long sweep its hard to tell. Give it another listen.

My other suggestion would be to fiddle with the bias. From what I read it sounds like you bought this brand new from MXR and didn't build it yourself. The factory is supposed to bias it correctly, but who knows....may the guy had to go to the bathroom really bad and did a rushed job on yours..... So fiddle with the bias....if this is the problem, its a really easy one to start. Gosh...I love when solution is easy. (for instance...my car died....I thought I just needed a new battery.....simple fix. Turns out something is fishy with the alternator...hopefully its an easy fix like a loose ground cable. Easy fixes are the best.)

[aziltz]

Ok, first off, I don't have a phase 90, but I have built two phase 45's....and they are sort of similar. What I realized is that a 500k pot is specified. But I get very little phased at less than 12 o clock too. With 500k resistance the sweep is SUPER long. I think it would be better served with a 250k pot. But I left my 500k pot in for 3 reasons. 1) laziness. 2) I wanted it stock(basically laziness again) and 3) I have found a few uses for a very long sweep....

So my first thinking is that your phase 90 is sweeping but its such a long sweep its hard to tell. Give it another listen.

My other suggestion would be to fiddle with the bias. From what I read it sounds like you bought this brand new from MXR and didn't build it yourself. The factory is supposed to bias it correctly, but who knows....may the guy had to go to the bathroom really bad and did a rushed job on yours..... So fiddle with the bias....if this is the problem, its a really easy one to start. Gosh...I love when solution is easy. (for instance...my car died....I thought I just needed a new battery.....simple fix. Turns out something is fishy with the alternator...hopefully its an easy fix like a loose ground cable. Easy fixes are the best.)

thanks, the pot was getting rusty/oxidized and lost contact, i fixed it and discovered that the surface mount phase 90 is the same as the EVH version.