Quick MXR '74 Vintage Phase 90 Fix

I recently purchased an MXR '74 Vintage Phase 90, but it had a couple of problems when I received it. First, the back plate bulged outward in the middle. I took it off, placed one end on a piece of wood and kneeled on it until it was straight. When I placed it back on the pedal, it was a very tight fit, but the bulge was gone. However, when I tried the pedal, it didn't work. The pedal sounded normal off, but when it was engaged, there was no phase effect. It sounded like a slightly muffled version of the clean signal. I removed the backplate, checked the battery, and looked around inside for anything obvious, but did not see anything. I tried it again before putting the cover back on, and the pedal worked fine.

Based on that, I assumed that two things that shouldn't touch were touching. The only thing I saw that could be doing that was the lug on the output jack that carries the signal. It was pointed up about 60 to 70 degrees, I would guess (about where the red line is in the photo below). I think this could have been touching a solder point on the bottom of the circuit board through the foam when the cover was on. I bent it down (gently), replaced the cover, and it has worked consistently ever since.

Original position of lug is indicated by the red line. I bent it down to its current position.

I read some reviews stating that the pedal  didn't work when received. So, if this is a design flaw, and others have had this problem, I thought I should make this info available. Especially because if you buy the pedal used you often don't have the luxury of returning it if it stops working.

Anyone have any similar experiences with the '74 Vintage Phase 90?

MXR Custom Shop Script Phase 90 is the EVH Phase 90

I'm posting this in the hopes that people considering the Custom Shop MXR line will be better informed:

I recently purchased an MXR Custom Shop Phase 90, thinking that I would treat myself to a reproduction of a vintage pedal. In the late 80's, I bought a mid-70's script Phase 90 for $20 and sold it a few years later for about the same. I often regretted it, so I bought the Custom Shop version, thinking it would be close enough.

The Custom Shop Phase 90 did indeed sound better than the standard Dunlop Phase 90, which has a touch of distortion and a rather harsh phase sound. I took the pedal apart to see if I could install an LED and found out that it is an EVH Phase 90 in a different enclosure. It isn't like the EVH pedal. It is the EVH pedal. It says EVH on the board (see left center of photo) and has the script switch (upper left), which is inaccessible with this enclosure. Installing an LED appears to be a simple job, but I was so disappointed by the surface mounted, decidedly un-70s vibe of this pedal that I sold it immediately and bought a '79 Phase 90 on ebay for $80, and it is chock full o' creamy goodness. I think the pedal was only $80 because (I was told) it is a transitional Phase 90 -- script guts, but with the block logo, characteristic of many MXR pedals in the late 70s. Even if it's not script electronics, it sounds gorgeous.

The Custom Shop Phase 90 does not sound bad at all, but I wanted either an old pre-Dunlop Phase 90 or a modern hand-wired version. I'm not ashamed to admit that I am among the majority of guitarists who would not be able to discern the difference between the Custom Shop/EVH Phase 90 and a 70's version (or handwired repro). But the simplicity and relative inconvenience (e.g., lack of DC adapter jack and LED) of the original have an allure that is difficult to explain.

MXR Phase 90 Mod

About twenty years ago, I was lucky enough to buy a 1970s MXR "Script Logo" Phase 90 for $20. They sell for up to $200 now, so I was pretty lucky. Unfortunately, I sold it before I ever used ebay, and didn't get much for it.

I have often wished I didn't sell it, so I finally purchased an newer (2002) MXR Phase 90 pedal a few months ago. I could not believe how bad it sounded. The waveforms were sharp -- unlike the creamy smooth original -- and the sound was dirty. To fix this, I bought a mod kit from Vodkamods.com. While I was waiting for the kit to arrive, I found the only modifications I needed (see the link below).

I removed the circuit board, clipped two capacitors (C11 and C12) and one resistor (R28). I also adjusted the trim pot to taste (The trim pot is just above the speed pot in the photo below). To do this, I had to remove the silicon plug holding it in place, and turned the pot a very little bit as I played the guitar through the pedal. When it sounded smooth and creamy, I stopped and marked it. They say to mark it before you make your adjustments, but if it sounds awful, why would you want to remember that setting?

Here's a photo from http://www.erikhansen.net/?page_id=31


I made a mistake with this mod, though. I should have clipped one component, played, clipped another, played, etc. to see what effect each had on the sound. Instead, I just clipped them all. I lucked out, though, because it sounds great. Also, if I were to do it again, I would remove the components with a desoldering braid instead of clipping them. Especially R28, which was tricky to get at.

Regardless, It sounds great, and if you're nervous about making the mod, don't be. The improvement was tremendous. What you should be nervous about, though, is dismantling and reassembling the pedal. I have read accounts of DIYers breaking the pedal by forcing something. With such compact pedals, there is not a lot of wiggle room. If something doesn't fit when you're reassembling, do not force it.

Now, back to Vodkamods: I didn't use anything in the kit. They seem like a good company, with good customer service, etc. I just didn't need any of the mods that were in the kit. The instructions were not well written, but when I e-mailed them a question, and they responded right away, so I would buy from them again.