EVH Phase 90

[Paul Marossy]

I can see it now, RDV will be selling clones of it...  :lol:

[sir_modulus]

Wow look at that "Bitchin' Blue LED" how original is that ?!? The Paintjob is quite nice though

[jimbob]

RDV- Now thats what i was talking about! Very cool!

[RDV]

All right! All Right! Calm down!

This doesn't exist....heeheeeheeee...

I drew it in MS Paint over my Phase 45 picture I took the other day.

The MXR one does exist.

Mine has a Blue LED too!

RDV

[Kleber AG]

"Hello,

You can remove the feedback resistor, R28, 24K. This will make it more like the classic script version and pretty much eliminate the distortion. If this is not enough, then remove C11 and C12, this mod will remove the pre and de-emphasis (noise filtering).Doing this modification will VOID your warranty. Were are not responsible for anything that will happen to your pedal.

Jayson Ocampo
Tech Support"

A long time ago, I think Doug posted this link:
http://vintageamps.com/PlexiPalaceUBBcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000412

Question:
I would like to know wich ones are C11 and C12 at tonepad's layout???

Regards
Kleber AG

[jimbob]

PostPosted: Wed Oct 20, 2004 9:10 pm    Post subject:
"Hello,

You can remove the feedback resistor, R28, 24K. This will make it more like the classic script version and pretty much eliminate the distortion. If this is not enough, then remove C11 and C12, this mod will remove the pre and de-emphasis (noise filtering).Doing this modification will VOID your warranty. Were are not responsible for anything that will happen to your pedal.

Jayson Ocampo
Tech Support"

Oh--now i remember this guy from a year ago when i had problems with a new phase 90 i bought that wasnt working and emailed them. He was hardly helpfull/ and i felt some what rude..Im trying to think of a polite word for " a real f_ck."

But it looks like he sorta helped above so...

But on the other hand- i was a real newbie not knowing my head from my arse as far as repair and DIY goes so maybe he was just tired of getting email like those from people like me? Who knows..

[cd]

Alright, what's the C11 and C12?  And why doesn't R28 change everything?  Check it out:

A vintage script logo P90:



Notice it corresponds exactly with the schematic at GEO, except for the feedback resistor.  We have six .05u caps, two .01u caps, and two 10u caps.

A vintage block logo P90 with a script logo board (single opamps):



This one is almost exactly the same as the one above, six .05u caps (two film), two .01u caps, two 10u caps.  FET resistors are 24k, and a 24k feedback resistor added.  The LFO resistor is 4.7k, but that's not a huge deal.  

Now we have a vintage block logo with a block logo board (dual opamps):



Lots of changes, more than just R28!  There appears to be six .05u caps and two 10u (or one 10u and one larger) caps, but there's an extra .01u cap and a 680pf (I assume) cap.  Those two are probably the C11 and C12 referenced above.  There are a bunch of other resistor changes as well, but I didn't pick through the whole thing.  

There you go, I shamelessly stole all the pics off the net so nothing from the bottom of the board or anything.  If you want the script 90, EVH style sound, my advice is to use the GEO P180 schem and leave out the feedback resistor.  If you want to mod a new P90, I suspect there's more involved than this one single resistor.

Anyone have a board pic of a new, Dunlop made P90?

[cd]

OK counting quickly, in the last pic (vintage block logo) I see an extra:

2 x 10k
2 x 100k?
2 x 56k
1 x 2.2k
.01u
680pf

[jimbob]

Great investigation and effort!!!!!

[TheBigMan]

Current Dunlop board



Quad opamp (TL064) under the pot.  I MAY one day try and trace the bugger out, but it's a double sided board.  

[mrsage]

Yeesh, if they're researching these forums, and thats the best they can come up with.... :roll:

I'm not taking credit, but a few months before NAMM, I posted on a forum saying that MXR could make a mint reissuing a script logo phase 90.

I'm not saying it was all me...Just an incredible coincidence.

[jimbob]

thats the one i used to have.

[Fret Wire]

On the reissue board photo, C11 is .01uf & C12 is 680pf. R7 (150k), which controls output level, is directly above C12 in the photo.

[cd]

Dang, that new one looks f'n nasty.  All that just to have everything PC mounted - yikes!

OK, who's going to post clear close-up board pics of the Zakk Wylde overdrive??

[vanhansen]

OK, who's going to post clear close-up board pics of the Zakk Wylde overdrive??

Good question.  I'm very interested in seeing the inner workings of that OD.

[cd]

Alright, I took the pic of the vintage block P90 and marked off all the parts that correspond to a script P90 with feedback resistor:

RED - Input
10k
.01u


YELLOW - Phase Stages
8 x 10k
5 x .05u
5 x 22k
4 x FET

BLUE - Power/Bias
trimmer
10k
10u
zener diode
polarity protection diode
1M
470k ?? 1M here?

GREEN - LFO
3.9M
4.7k
15u
2 x 150k
470k
.01u

ORANGE - Mixer/Output
4 x 150k
56k
.05u
transistor

Leftover:

2 x 10k
.01u
680pf
150k
2.2k
2 x 56k



So, does anyone know (or care to speculate) where the leftover parts go?

[stm]

Very thorough work!  Can you past a picture of the other side of the PCB?
With that I'm quite sure I could figure out the complete thing...

[cd]

Very thorough work!  Can you past a picture of the other side of the PCB?
With that I'm quite sure I could figure out the complete thing...

Read my other post.  I stole all the pictures off the 'net so no trace side photos.

[stm]

Ahhh... B*U*M*P !

[dubs]

O.k another challenge - true bypassing it. The buffered bypass apparently sounds horrible with humbucker guitars.