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From Nero1985:

Hi!

Here you find out how to turn your Phase 90 that you just got a Guitar Center into the Script Phase 90 wich is not just a R28 mod or the C11 and C12 mods, it goes beyond that.
There are 8 components on the new P90s that werent on the Script logo used by Eddie Van Halen and many others, here you can see what components have to be removed and wich ones replaced.
Im also including a picture of its board with the component numbers so that u dont have to look for them all night long just to remove it or replace it!
The Script Mod was tested by me and worked amazing, you'll get a very nice phase that might not be great as a pre distortion pedal but if u run it on ur Fx loop of after a Tube Screamer (like i do) you'll a crazy Phase!
The OTHER MODS havent been tested but they should work fine.

It took me a hours to realize the structure of the new P90 so i hope it helps you....

http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90_to_Script.gif
http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90_board.sized.gif
http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90_Script.gif
http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90.gif
http://aronnelson.com/gallery/albums/Schematics-etc/phase_90_board.sized.jpg

Would it be possible to change the color of the part numbers? I'm partially color blind and I can't make out most of them.

Thanks!

Wow, awesome, Nero.  Would it be possible to clean up the PCB with the part numbers and make them yellow?  If you want, download the pic again from my site.  It's a clear .jpg, and that's what you want to save it as.  .gif will make it lose lots of colors, as you've seen.

I'll give this a shot.  My wife may wonder what the heck I'm doing since she bought it for me. :D  Ah well, the price we pay for good tone.

i hope it helps, it made mine soun GREAT!

i also changed the 24k resistors for 22k,

that pic of the phase 90's board, i cant remember where i found it, if u had it let me know cuz i wanna give u credit as well

Quote from: Strat Cat on October 04, 2005, 07:04:23 AM
Would it be possible to change the color of the part numbers? I'm partially color blind and I can't make out most of them.Thanks!

Strat Cat, I have unusually good color vision (test score 100%) (mind you I have plenty of OTHER things wrong, can't drive a car!) but, I can't tell the components either. So it isn't just you! If you view in IrfanView (free!) then you can modify the color mix to optimise viewing. IrfanView is a handy thing to have anyway.

Quote from: nero1985 on October 05, 2005, 12:10:57 AM
that pic of the phase 90's board, i cant remember where i found it, if u had it let me know cuz i wanna give u credit as well

The photo was taken by me about a year or two ago. This is the original.
(http://pic5.picturetrail.com/VOL83/511092/1450949/61785738.jpg)

Quote from: Paul Perry (Frostwave) on October 05, 2005, 03:48:43 AM

Quote from: Strat Cat on October 04, 2005, 07:04:23 AM
Would it be possible to change the color of the part numbers? I'm partially color blind and I can't make out most of them.Thanks!

Strat Cat, I have unusually good color vision (test score 100%) (mind you I have plenty of OTHER things wrong, can't drive a car!) but, I can't tell the components either. So it isn't just you! If you view in IrfanView (free!) then you can modify the color mix to optimise viewing. IrfanView is a handy thing to have anyway.

Well I tried it but I still can't make out most of the labeled components. Especially the resistors above C12 as well as others.

Try this.

http://aronnelson.com/gallery/albums/Schematics-etc/phase_90_board.sized.jpg

That's much better. Thank you!

Now that the differences between the Script and Block logo versions have been finally unveiled, I think it is a good time to clarify the different models around. I have seen the P90 being named in many different ways, like:

*Phase 90 Script [logo]
*Phase 90 Block [logo]
*EVH Phase 90
*Phase 90 Reissue
*Phase 90 Original

However I understand (please correct me if I'm wrong), that there should be three (03) different sounding versions out there (?):

1) Phase 90 Script Logo = Phase 90 Original:  This is the original version, *actually* used by EVH (true or false?)

2) Phase 90 Block Logo = Phase 90 Reissue:  This version has a modified circuit intended to *reproduce* the actual EVH's tone when his *tube amps* were overdriven. As far as I can deduct from the many posts around, this version is not so popular as the Original one.

3) EVH Phase 90: This is a special version with a custom paint job (crossing stripes). I understand it has a white pushbutton somewhere that changes from Original to Reissue perhaps?. Don't know how it compares to the Script and Block logo ones.

You are welcome to correct and add to the above info.

Quote from: stm on October 05, 2005, 09:47:04 AM
Now that the differences between the Script and Block logo versions have been finally unveiled, I think it is a good time to clarify the different models around. I have seen the P90 being named in many different ways, like:

*Phase 90 Script [logo]
*Phase 90 Block [logo]
*EVH Phase 90
*Phase 90 Reissue
*Phase 90 Original

However I understand (please correct me if I'm wrong), that there should be three (03) different sounding versions out there (?):

1) Phase 90 Script Logo = Phase 90 Original:  This is the original version, *actually* used by EVH (true or false?)

2) Phase 90 Block Logo = Phase 90 Reissue:  This version has a modified circuit intended to *reproduce* the actual EVH's tone when his *tube amps* were overdriven. As far as I can deduct from the many posts around, this version is not so popular as the Original one.

3) EVH Phase 90: This is a special version with a custom paint job (crossing stripes). I understand it has a white pushbutton somewhere that changes from Original to Reissue perhaps?. Don't know how it compares to the Script and Block logo ones.

You are welcome to correct and add to the above info.

Close, but there are really 4.

Phase 90 (script logo)
Phase 90 (block logo - first with single op-amp script board and then later with dual op-amp block board)

By Dunlop:
Phase 90 (reissue)
EVH Phase 90

There was a thread about the EVH model a while back and cd graciously shared photos of each of the early boards and the differences.  I have taken that info and put it on my site.  There's a link to it on my Phase 90 mods page.

Nice, thanks for the info!  :)

HI,

I thought You can't really mod a block logo or reissue P-90 to script specs, as the circuits are too different (# of chips, etc). And there were more than one version of the script logo, with different numbers of chips. MXR used revision numbers on the boards, i.e. rev 108 came out in 1978, which rev is your mod? My 1974 P90 (Bud Box) has 6 chips in it as does my later 76 script logo.
in 1979 they changed from 741 chips (single op amps) to TL062 duals, so # of chips was reduced. You should replace the op amps with 1458 chips for a script mod.

have fun!

u can turn a reissue phase 90 into a script with the mods above, in my case i changed it all! and it sounds great, the only thing that i havent changed from it are the output resistor (10k) as when i bypassed it it distorted and the phase dissapeared,

u can also even change the .047 caps if u find the .05 but thats up to u, im going to add a new schematic with all the mods possible for the new phase 90  as soon as i get a chance

cheers

Check the sound samples here

http://www.diystompboxes.com/smfforum/index.php?topic=37943.0

I'm having trouble accessing Aron's links in the initial post above, anyone else?

I keep getting (2 days now):

"The page you are looking for is currently unavailable. The Web site might be experiencing technical difficulties, or you may need to adjust your browser settings."

They work fine for me.  Go right to the Layouts Gallery and see if you can get to them that way.  They're in the Schematics folder.

try here

http://aronnelson.com/gallery/Schematics-etc

Awesome work Nero.  I hate to imagine how long it took you to trace out a Dunlop Phase 90.  :o

thanks, yeah it took about 5 or 6 hours to do it, i did it at night and i wanted to help everybody so that way we have more mods for this pedal im a big PHASE 90 fan and a big Cry Baby fan as well so ill be posting some interesting mods for the CRYBABY soon ;)

Wow, what a great thread, this is my first post here, but I recently got a used P 90 w/ the R28 already removed.  However, yesterday I went in, and with help from the pics here clipped C11 and C12.  I spent an hour or two trying to adjust the trim pot by ear and I think I got it. 

Anyone want to listen to clips and tell me if I got close (with the trimmer)?  Speed is on noon, LP bridge to tube screamer to Phase 90 w/mods, no delay added to mild OD tube amp.  Thanks for any comments on the trim setting:

http://www.tedm.com/mp3s/phase4.mp3

I know I'm dredging up a really old topic, but I was wondering if someone had the power section schem that is missing from these schems? I just got a fried Phase 90 RI that someone plugged the wrong adapter into.

Any help is appreciated (big thanks to Nero for those schems) :)

Thank you!

Well, I got it fixed. The diode (not the zener) was out. I'm going to try the mods listed here; I can't wait to see what it sounds like after!

Did anyone do the full mod changing a bunch of the components inside of the Phase 90 Reissue.  If so how were the results?  Does it sound like the EVH Phase 90 in script mode, OR does it sound like the original MXR Scipt Phase 90?  I'm kind of interested in buying a Phase 90 and modding it to sound like an old Script Model MXR Phase 90. 

- Future_Faze

I did the full script mod to the letter. Put a switch for adding/subtracting the R28, and a DPDT switch for adding/subtracting both C11 & C12. Also drilled a small hole so I could adjust the trimmer without taking it apart. I couldn't find a 1m trimmer so just added a 1M resistor. (I'll chang that later)

(http://i39.photobucket.com/albums/e185/LoudGreg/Phase90Mod.jpg)

It makes it a much smoother mellower Phase 90 but I think my Bud Box script has more "swirl" to it. But it's ever so slight.

Yes, thats the kind of info I was looking for.  Any others are welcome to share their experiences on this full mod to the MXR Phase 90, compared to the Original or EVH MXR.

Thanks again, Future_Faze

Does the trimmer need to be adjusted only if you remove c11 and 12?  I stuck a toggle switch on R28 but have never messed with the trimpot.

Google brought me here.  Why did I even try looking all over the web? I should have known I'd end up here in the end. :D

I'm trying to find a pic that identifies the part numbers on the Phase 90 board. Looks like this would have been my source. Aron, any chance you could repost those four pics from the first post in this thread? They seem to be long gone from your site. I've got an 04-27-2001 Rev E board if that helps identify the picture I'm after.

Thanks!

- Ian

Here's a couple of pages from Erik Hansen's site that helped me a lot, covers all the different versions of Phase 90.  I have the early Dunlop version, which turns out is almost identical to the later original MXR version, and I had a lot of trouble finding info for my version:

http://www.erikhansen.net/?page_id=31 (http://www.erikhansen.net/?page_id=31)

http://www.erikhansen.net/?page_id=32 (http://www.erikhansen.net/?page_id=32)

Al

Thanks Alan! That's the site I used last year when doing the R28 mod. Unfortunately he hasn't got my board with R7 identified on it (he's only got R28, C11, C12 labeled in this picture: http://www.erikhansen.net/diy/phase90scriptmod.jpg). Everything I've found so far references Aron's original URLs for pictures that label everything.

Anyone know which 150k resistor in this schematic (http://www.geofex.com/FX_images/p180.gif) is the R7 resistor that Erik refers to? If I'm guessing I'd say it's the first resistor I hit when I trace back from the tip of the output signal. wrong?

This layout from the gallery here shows R7, if that's what you need:

http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/MXR_Phase_90_board.gif.html?g2_imageViewsIndex=1 (http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/MXR_Phase_90_board.gif.html?g2_imageViewsIndex=1)

Al

Thank you so much, that's exactly what I was after!