About the MXR Phase 90

[nero1985]

ok i wanna buy one, its eighter the regular phase 90 or the VH phaser, so i just wanna know how i could turn a regular one into a VH phaser, any schematics? i saw of picture of its guts and it looks like it has that DOUBLE SOLDERING POINTS with i hate cuz they r hard to deal with so if u have any info i would appreciate it!


ROCK N' ROLL!

[Danny G]

The "script" mod that the EVH features is a toggle switch for the R28 mod.  

Find R28 (ask on this site, people can point it out for you).  Desolder one leg and replace it with a wire.  Run the other end of the wire and the now free leg of R28 to a simple 2-pole toggle switch.  Voila, the EVH Phase 90 for about $1.50.

Finding the best location for the toggle switch can be a little tricky, but no problemo.

[jimbob]

Can it really be that easy? I want to believe.

[vanhansen]

No, I don't think it just switches the resistor in and out.  There's got to be more to it than that.  There is more to making a current Phase 90 a "script" version than removing R28 from the circuit.

[Danny G]

Sounds great on mine.  R28 on for slower phase rates.  R28 off for faster rates and a more Univibe feel.  Swiiiiiirly.....

[jimbob]

I bet someone around here knoes there diff between the 2.

[Joe Hart]

I think you also remove C11 and C12. And possibly the output resistor (the reissues give a little bit of a boost).
-Joe Hart

[vanhansen]

If you really want to see the differences circuit wise, I have a page that took what cd posted a while back in another thread showing the differences between the original script logo all the way up to a vintage block logo.  I wanted to preserve that info in case the thread ever disappeared.

http://diy.erikhansen.net/phase90diff.htm

This is the only way to get to this page.  I don't have it linked off my Phase 90 page.

EDIT (8/20/05):  This page is now accessible from the MXR Phase 90 Mods page.

[jimbob]

Great site!

[Fret Wire]

This is the only way to get to this page.  I don't have it linked off my Phase 90 page.

Here it is.
http://diystompboxes.com/sboxforum/viewtopic.php?t=26093&postdays=0&postorder=asc&start=0

http://diystompboxes.com/sboxforum/viewtopic.php?p=224374&highlight=#224374

The "R28" mod is not a complete "script mod". It is, however, a big improvement on the reissue, and makes most people happy.

Removing C11 & C12 from the reissues will not get you a "script mod" either. It will really mellow the unit out, what I call the "Phase 70 mod".

The problem with the whole "paint by part numbers & picture modding" is that there are no schematics given, and no understanding of the part's actual function. All is fine until you want to change the mod slightly. If you want to mod a reissue to true script specs, you must start with schematics for both the script and reissue, have an understanding of what the different components actually do, and then it's easy.

Nero: Yes the boards have plated through holes, oversized enough where each component has a sizeable solder pad on the component side of the board as well as the trace side. It's one thing to snip out components on these boards, it's an entirely different beast to completely remove them. Solder suckers (pumps) don't work well on these. Braid does better, but a real desoldering station is the best way to go on these.

Let's not forget that these reissues are only worth so much effort. You still end up with a pedal that has jacks, switch, and pot that fail sooner than the standard type, no true bypass (if you require it), and the last time I checked still no Boss style dc jack (if you need the Boss style).

With a reissue, I'd recommend that most people stick with the R28 mod, C11 & C12: if you want mellow, adjust for unity gain: different values needed depending on whether you mod one or both of R28/C11 & 12, and led/led resistor changes. By the time you've desoldered R7 to adjust unity gain, and desoldered the led and resistor, you'll have already had your fill with this pedal. Maybe sometime I'll post the complete script mod for the reissue, but for most people it won't be worth the time.

Nero, if your considering buying a new reissue or EVH, then consider the kit from BCY. It cost about the same, and is probably easier on the nerves to build the kit, than simple mods are for the reissue. It even comes with matched jfets. You can build yours from scratch too ( I did), but then you have to buy and match jfets, set up your own layout for the box, etc.
http://www.buildyourownclone.com/phaser.html

Just something to think about if you want the true script sound.

[vanhansen]

This is the only way to get to this page.  I don't have it linked off my Phase 90 page.

Here it is.
http://diystompboxes.com/sboxforum/viewtopic.php?t=26093&postdays=0&postorder=asc&start=0

http://diystompboxes.com/sboxforum/viewtopic.php?p=224374&highlight=#224374

The "R28" mod is not a complete "script mod". It is, however, a big improvement on the reissue, and makes most people happy.

Removing C11 & C12 from the reissues will not get you a "script mod" either. It will really mellow the unit out, what I call the "Phase 70 mod".

The problem with the whole "paint by part numbers & picture modding" is that there are no schematics given, and no understanding of the part's actual function. All is fine until you want to change the mod slightly. If you want to mod a reissue to true script specs, you must start with schematics for both the script and reissue, have an understanding of what the different components actually do, and then it's easy.

Nero: Yes the boards have plated through holes, oversized enough where each component has a sizeable solder pad on the component side of the board as well as the trace side. It's one thing to snip out components on these boards, it's an entirely different beast to completely remove them. Solder suckers (pumps) don't work well on these. Braid does better, but a real desoldering station is the best way to go on these.

Let's not forget that these reissues are only worth so much effort. You still end up with a pedal that has jacks, switch, and pot that fail sooner than the standard type, no true bypass (if you require it), and the last time I checked still no Boss style dc jack (if you need the Boss style).

With a reissue, I'd recommend that most people stick with the R28 mod, C11 & C12: if you want mellow, adjust for unity gain: different values needed depending on whether you mod one or both of R28/C11 & 12, and led/led resistor changes. By the time you've desoldered R7 to adjust unity gain, and desoldered the led and resistor, you'll have already had your fill with this pedal. Maybe sometime I'll post the complete script mod for the reissue, but for most people it won't be worth the time.

Nero, if your considering buying a new reissue or EVH, then consider the kit from BCY. It cost about the same, and is probably easier on the nerves to build the kit, than simple mods are for the reissue. It even comes with matched jfets. You can build yours from scratch too ( I did), but then you have to buy and match jfets, set up your own layout for the box, etc.
http://www.buildyourownclone.com/phaser.html

Just something to think about if you want the true script sound.

I can never remember the title of the thread it's in.  Thanks for finding it.

Based on the information you have provided in the past and here, I'm probably going to update my page a bit so it is understood that those mods will not make the reissue a script logo Phase 90.

[vanhansen]

Great site!

Thanks.  It's a constant work-in-progress.

[nero1985]

THANKS ALL OF U GUYS! im going to buy the EVH cuz well..... I GET IT FOR FREE hehe i just thought of maybe modding the stock PHASE 90... THANKS AGAIN!!!!!