Mondo Morley Medicale: PWF Power Wah Fuzz

This monster, the Morley Power Wah Fuzz, came to me via Sir John Cadbury Cobbett.


On his former quest to have the largest pedal board in the world, partially I think to mock me and my increasing effects collection, John decided to collect some old Tel-Ray Morley pedals. I knew they had a wah and volume pedal, but I really had no idea how many effects this company produced in the ’70s. Rotating Wahs and echos utilizing oil cans, flangers and phasers whose sweep could be automatic or controlled by one’s foot, some weird shit called a pik-a-wah that used a metal pick to wah while you played? And they all came in the same gigantic big chrome box that just says, “America, fuck yeah.”

This era ended in the ’80s, thanks to the big evil Japanese overlord Roland and their BOSS compact pedal line. Electronic switching and cheaper priced parts led to the destruction of stupidly oversized and bulletproof pedals with rich sounds, and instead led the way to huge pedal boards full of piles of middle-of-the-road disposable doodoo for the middling shredder of the ’80s who needed to hit a different pedal for each solo. For some more on the history of Tel-Ray Morley and their line of colossal chrome pedals, check this excellent link:

A quick note… I despise when folks refer to anything well made as “built like a tank” because tanks break down a lot. They’re big, eat gas and spit out freedom, but they fall apart constantly. “Bulletproof” is a tad more accurate if you’re describing something as well made.

John gave me the PWF in a non-functional condition. Or so it seemed… you see, Morley’s are unique foot pedals in that Ray of Tel-Ray invented an optical system to replace the traditional potentiometer in a wah or volume pedal. There’s no gears moving, instead, the foot pedal moves a curtain that opens up or blocks light from the power indicator. These are old school bulbs, so they burn out after awhile, and a lot of people think their Morleys are toast, like the fool John bought this pedal from. They won’t make any sound at all if that light doesn’t turn on. This part is an easy fix.

First unscrew the back plate here…


Replace this bulb, a model 387, with the replacement you bought from the weird old couple that won’t look you in the eye and who run your local electronics shop that smells of mothballs and cat pee. Alternatively, you can find replacements on eBay from third parties or from the current owners of the Morley brand name here.


Plug directly into an AC outlet (gotta love the full 110v action) and flip the gigantic, clunky switch to “on” (gotta love a pedal with an “on” switch)…

And your Morley is no longer dead.

Unfortunately, in this case, the Morley might not have been dead, but it was very sick. This is a Power Wah Fuzz… except there was no power to that damn fuzz. And the wah sounded stupid and moved in reverse. There was a few more problems for the doktor to tend to…

First off, the wah. These things, when working properly, have a HUGE wah sweep that sounds pretty incredible. Less like a traditional Crybaby, more like V’ger in Star Trek: The Motion Picture (an absolutely horrible film, but the bald chick is hot and V’ger sounds cool). The optical sensor as an end is so cool and futuristic in these effects, but the means to get there is as primitive as it gets. It’s a curtain. And sometimes the curtain gets loose and flops around inside, because it’s held by black masking tape. Fucking. Tape.

Yes, fucking tape.
Yes, fucking tape.


Unfortunately, I already fixed this, so there’s no before and after. But here you can see the box that covers the light sensors and the curtain as it appears when the footpedal is rocked all the way back. It completely covers the light sensors, with one end attached to the bolt that comes from the footpedal, and the other end curled around and secured to the top of pedal with… tape.


Here it is with the footpedal rocked forward. The curtain rolls back from the box and exposes the sensors to the light from the power indicator. The box that is secured to the circuit board with… tape.

I dimmed the lights, and turned the pedal on. Being very careful to not electrocute myself with 110v, I adjusted the light sensors height (gently, as to not break the legs) so that I would get a full sweep of light over it along with a full sweep of the pedal.


Now, the wah was working fine. Better than fine, it’s wicked. But the fuzz was less like a Big Muff and more like an Italian ass. It distorted, but it sounded weak and had no bite. I heard a bunch of demos on YouTube that sounded the same as this, so I thought maybe it was fixed and this model pedal just sucked. No way, though, this was a model pedal that Cliff Burton had rocked on! There’s no way the major rager on the four string mother fucker would’ve chosen a pedal that sounded like an Italian ass.

I downloaded the schematic for the PWF from the Tel-Ray Morley support page. I’m no engineer, and I can barely read this stuff. I’m just a poor DIY guy who tried his best not to pay someone smarter than me if I can go ahead and break something more first. Long story short, I poked and prodded. For days. Finally, I had the notion that maybe something was wrong with the clipping stage, the part that makes the amplified signal distort. Duh, I mean, it was the fuzz that wasn’t fuzzing, right? I tried and tried to find the clipping diodes as indicated in the schematic by following the circuit board, but they weren’t where they were supposed to be, parallel to R28 on the schematic.


And herein lies the mystery… because I never took the whole thing apart. I didn’t have to. Is this board two-sided with the diodes on the other side? I’ll never know, because I just prodded the area with a typical N4148 diode where I thought one should be, and voila, I had a bad ass fuzz coming out. There must’ve been a blown diode somewhere, and this one was filling it’s space in the circuit path. So I soldered that little shit right on top there and was good to go.


The sound is a great fuzz, very similar to a Big Muff Pi with a little less bass response. The magic, though, happens when you hit the fuzz and the wah together. It’s like a rocket taking off and landing on a disco ball.

Finally, to polish the body, I took a low grade steel wool from the hardware store, grade #0000, and scrubbed down the chrome until it shone like C-3PO during a racist awards ceremony where Wookies are treated like second class citizens. 3/5th a vote in the galactic senate, so I hear. And then John didn’t want the pedal anymore because he was broke. So he sold it to me. Woo hoo! Time to play Anesthesia (Pulling Teeth), one of the most obnoxious uses of a bass and wah and fuzz in the history of rock ‘n’ roll!

Before I bought this one, though, I almost bought another PWF at a used store. The guys told me it worked great, and it had EVERY PROBLEM John’s had had. I tried to explain it to them, and they didn’t seem to care much. Actually, like a lot of people I talk to, I watched their faces glaze over in apathy. Hopefully, though, my experience is a “teachable moment” (God damned patronizing term) to someone else who thinks they have a bummer pedal their ex-rocker dad gave them just sitting in their closet collecting dust. It’s could be the same, easy-to-solve issues. Then you can rock like this dude on the sticker I found on the bottom of my PWF…

Way to design a timeless logo, Morley.
Way to design a timeless logo, Morley.

EDIT 18/5/2018: Here’s the schematic.


64 thoughts on “Mondo Morley Medicale: PWF Power Wah Fuzz

  1. I'm rebuilding one of the bad boys right now, and the previous owner was a real toolbox apparently. Any chance you could put up a schematic for your tone and intensity controls? I rebuild the circuit to the schem Morley provides and it was a no go. Thanks in advance!

  2. My PWF matched the schematic provided by Morley, so I'm not sure I can be of any help here. You may just have a component not working, ya might have to use the shotgun approach on that. The only help I could really be is some photos of mine, in case something has been hooked up wrong.

  3. Hmm. I've already replaced the pots so we're good there. If you could post a close up or two that would be awesome. Maybe I had just soldered something backwards… wouldn't be the first time, haha.

  4. So I love the article and the site in general. So I have had my PWF for quite some time and it's been through the trenches and when it's working great it is phenomenal. I had the exact same problem a year or so ago and I attempted to resecure the curtain. Well it works but now everything is backwards. Sweep, volume and even the pots on the side. Is it possible the curtain length is too long. How would that affect the pots. I'm kind of scratching my head here. It still seems to be working correctly but it is really cumbersome in live scenarios. Especially after 6 or 12 in ya.

    1. Why your pots would work backwards without some re-wiring is a head scratcher… did you? But as for the sweep being backwards, sounds to me like you possibly didn't re-secure the curtain properly. It needs to be curled. If it's loose, it could create the symptom you describe. Open up the bottom of the pedal and make sure that as the pedal is moved towards the heel, the curtain moves to shade then cover up the LDR that is soldered to the terminal strip. Refer to this entry:

      1. You are correct. Now that I am looking at pictures I think I know what I did wrong. The curtain is not curled underneath the rod (for lack of a better term) but attached above the light sensor. Which when I took it apart the first time that is how it looked like it was supposed to go. Initially the box that went over the light sensor was torn. So I rebuilt it. I will try to reassemble tonight correctly

  5. Men awesome comments there!
    I fix my sensor the way you mention to have a full range of light, but I have a question, the second sensor is supposed to be laying there up side up, I don't know how to describe but the one in the right is vertical facing the curtain and the other is looking up to the box, is this ok?
    Thanks bro!


    1. It depends on how it affects the effect. If everything is working fine, don't touch them. Of course, you can try adjusting them, just be careful not to break the wires.

      1. Hello,
        Recently got one of these mutha's. All seems fine, but when you engage the fuzz on its own, the volume drops out, low output kinda thing. Any ideas ?

        1. Try fixing the diode problem like I talked about in the article… you could have a blown one on the clipping stage that might be causing what power loss. There's lots of other issues that could arise with bad ICs. In general, though, the PWF does drop a SMALL amount of volume when the effect is engaged. Nature of the beast.

  6. Thanks for the great, informative post! I too have one of these that I love for it's loose, freewheeling vibe and over the top screedle / mind-melting psycho-skronk. So, reading this, I'm curious if you also have an issue with 60 cycle hum outta this chrome barge. I'm wondering myself, how to remedy it… possibly with a 3-prong plug? Did you attempt this?

    That being said, mine also produces that ratty fuzz you described. Yup, it's nasty and thin and pretty belligerent but I kinda like it, especially with the wah engaged and going through a delay/echo and reverb'ed out amp. What I might do is that clipping diode move at R28 which you suggest… with a toggle on the outside of the box to turn it on and off so as to have both options. You make it sound so good I think I have to try it.

    1. The 60 cycle hum has to do with the power transformer being inside the box… I think you'd be hard pressed to get rid of it and still use the plug. You'd probably have to wire a transformer outside the unit and feed straight DC into the circuit.

      1. Ah thanks for the word. Guess I just live with it as is, in it's beastly, untamed state. Can't complain… it's awesome. To follow up, I did do the diode move you mentioned… success! Sounds great… thanks so much for posting your findings!

        Now I love the fuzz sound. I think it also sounds amazing with the guitar volume rolled down… It made me realize there's really no way to dial the gain back on this thing- it's either bassy or trebley via the TONE control, or loud or quiet via the INTENSITY control, but it's always full-bore Fuzz. It would be nice to somehow add another pot to control the amount of Fuzz (like you get with guitar VOL turned down, but with less line hiss). Hmmm!

      2. You could build a wallwart power supply for the transformer. Or just leave it.

  7. May be of interest, got a reply from Scott, Morley tech.

    There are 2 controls on the side that affect the Fuzz one is Fuzz intensity and the other is Fuzz Tone I would try cleaning these with Caig Fader Lube first remove bottom cover and spray a little inside each pot. Second thing I would check is the vinyl shutter inside make sure one end is attached to the threaded rod and that the other end is taped down to the base inside just infront of the hole the threaded rod comes through. It is typical for the tape to degrade over time. If the shutter has become untapped then remove the old tape and glue with some Goo Gone then alchohol and retape the shutter back down with black masking tape. If this does not resolve the issue then the volume LDR may need to be replaced. It controls the volume when the Fuzz and WAH are off but when you turn the Fuzz on it should go from a dry sound toe up to Fuzz toe down.

  8. Done the little diode trick, and also changed the intensity pot. Sounds and works better, the volumes still a little to low, when looking about I think I may have found the culprit. Down near the transformer there looks to be a burnt out resistor ( looks discoloured, also the solder looks like a cold solder at one end). I can't identify it, I'm also shit at reading schematics. It's above the the first bluething to the right of the transformer( marked 50v47uf). I can see a brown and then a green band but the rest of the colour bands look singed. If I can identify and replace it I'll be rockin. Help me doktor sewage , your my last hope.

    1. The two resistors that are attached to that capacitor shouldn't affect the volume. It's either a 1.5k that is attached to the voltage rail or a 150 Ohm resistor which is attached to the lamp. I'd take it out and test its resistance just to be on the safe side, but I'm guessing its fine or the pedal or lamp probably wouldn't work at all.

      This pedal does usually have a small dip in volume from clean to distorted. Some of this can be mitigated by adjusting the LDR so it gets more light when the foot treadle is all the way down. There might be other ways to mod the original schematic, but unfortunately, I don't have the pedal anymore to experiment on.

    2. Had another thought on this… like I said, the distortion does have a slightly lower volume on the PWF, at least mine did. You could try swapping out one or both clipping diodes for standard red LEDs. LEDs allow a louder signal through, but it will change the sound of the distortion a bit from buzz saw to more of an organic overdrive. It might sound better, it might not. It will definitely be louder.

      1. Cheers Doc, the only thing is I have no idea what the clipping diodes look like. Any pointers would be greatly appreciated. And LED's, as in the wee light things ? ( As you can tell I'm great with tech stuff). Doc I owe you a beer for putting up with my stpidity. Your a legend.


        1. You stated you did the diode trick as I did it. The one I called "little shit." Try putting a standard red 5mm or 3mm LED in its place. Size doesn't matter, here. Just make sure the polarity is correct… the shorter leg of the LED (the cathode) will attach to the side where the striped part of the diode is currently connected.

  9. Doktor, done the LED trick………… were 100% right. It's nuts !!!!!
    Any other tricks up your sleeve for the Morley ?

    Cheers mate, really appreciate the help.

  10. I have one of the new cliff Burton tribute model pfw and the way the light and sensor are configured are different and I want a longer sweep. Any ideas on how I may be able to modify the, for lack of a better word, "window" between the two? Thanks

    1. I would have to see the inside of one of these newer ones to give a definitive answer. I'm assuming it still has the LDR, so if you wanted a longer sweep, you'd want the LDR to be angled away from the light source more, so it takes longer for the light to sweep across the face of it. Like a sunset. But, I'm also assuming they've made playing around the inside of these more difficult to do as electronics shrink. Good luck!

  11. I just bought a PWF that was missing the Fuzz & Wah DPDT switches. The wires were hanging out like Medusa’s snake hair. I found 2 schematics and had to determine which would work. After a failed wiring of the newly purchased DPDT switches, I finally got it right. But, there was no Wah sweep or Volume change when using the foot adjustments. After a week of scratching my head, I finally noticed that the shadow curtain had detached from the chasis. I taped it back and Wah-Lah….WAHHHHHHH!!!!. This pedal kicks ass!

  12. Hi

    I have a Telray Power Wah Boost.
    Its in really good condition.
    Only thing I find annoying is how subby it sounds when the heel is down in wah and boost on. I mean its really tone sucky. No clarity.
    I emailed morley and their response was move the LDRs so more light is on them. Problem with this is its already into the wah sound by doin that.
    To me ( I could be wrong ) but it sounds like when the shutter is shut and light is blocked it goes to a different part of the circuit? If you rock heel back slowly you hear wah sound change like as if that section would be bypassed.
    In relation to Cliff Burton Kill em all tone. It is crystal clear with no subby muddy tone. Even when he plays live.
    I know mine is PWB and his is PWF but other than the boost and fuzz the wah section should be built the same. True?
    So do you think somewhere I could have a diode or somethin out? Or is it just the way the pedal is?

    Thanks for your time.


  13. So here we are in 2017 with more questions on the same old device. I found a FW-1 (circuit board) Morley as shown in this blog. It is missing two things, the back plate that held the bulb, and the transformer with a rewire to the outside. Probably someone had a power pack or something hooked up. So….. does anyone know the voltage drop on T1? Also, I saw the bulb number in this blog, and should be about to make a mount. Anyone got parts?
    Thank you.

  14. Hey,

    this is great story. And yes, I may have similar issues including the tape issue ;-).
    I just grabbed one of this monsters out from trash (incl. a brand new chrome chassis for spare). But I can not find the schematics at Morley’s website anymore. Can you mail me the pdf please so I can fix mine as well?

    Would be a great help to me.

    Thank a lot in advance from Germany.

    Best Jens

    1. Bummer. They used to have all their schematics up for download. I guess they took ’em down. Good thing I saved ’em all… emailing to you now.

  15. Hey dok I’m having a lot of trouble with my power Wah Boost I have no idea what is wrong with it, the Wah only seems to move when the pedal is close to the heel down position, I have been trying to fix it adjusting the curtain and the position of the ldrs but nothing seems to change. I really need help on this one.

  16. Can you e-mail me the schematic for the Morley Power Wah Fuzz? I just scored one of these and would like to try out your mods. Thanks!

  17. Hey Ross,
    Excellent thread here; I really appreciate all the info as it looks like my PWF might finally evolve from a shelf filler to something that sees some use. I too could really use the schematic as it would appear that Morley has removed it (likely due to the introduction of the Cliff Burton model). Thanks again for so much quality information.

  18. What value is the resister that is by the transformer that seems to be the first one to fry in this pedal?

    1. The only resistor that is directly tied to the transformer, according to the schematic, is 150Ω. You can download the schematic at the end of the original post.

  19. Hi,

    Does someone have any clue on switching the PWF to European 220V AC power supply?



    1. Morley used black masking tape. If you can get this it works, or if you have black electrical tape lying about, that works too.

  20. Thanks for the tip on the diode, I was wondering why mine sounded so weak when the fuzz was on. Now it screams!

  21. So many thanks for your help !
    So strange they forgot those diodes on so many pedals … perhaps an early Rev
    For information, I checked on mine and this is not a double side PCB so no hidden diodes there.
    Finally, I had a question, why didn’t you set 2 diodes like drew on the schematics ?

    1. weird! Maybe it was forgotten on the circuit board print, and they had like thousands already, and some bozo just forgot to add additional diodes when populating it. Pretty sure that happened on the old Phase 90s; they have a single resistor wired off the PCB. Anyway, I didn’t add two diodes because it sounded good. I guess I left this one asymmetrically clipping instead of the usual symmetrical set up. It’s a perfectly valid way to go, a different sound for your distortion. Try both and see which you like better!

  22. I have a 1976 Morley power Wah. The bulb went out and it popped the new ones I got. I’m reading 41.5v at the bulb wire. The resistor is done isn’t it ?

    1. that seems about twice as high as i remember it needed to be… my advice is to try and run the pedal in the dark and use a flashlight to simulate the bulb. if the pedal seems to be working, than yes, it is likely the resistor r7. if the pedal will not work with a flashlight tripping the ldr sensor, you have a bigger problem with the transformer.

  23. I went online and found information I was exactly looking for by finding this article, just like in the old days. Thank you so much (I am calibrating one of these for myself).

    1. happy to help! I try to archive things as i learned them and help others.

  24. Heya Dok i picked up a morley PWF and im gonna replace the bulb on it but a strange trouble i have is when the fuzz and wah is engaged the tone is overpowered by the treble and mid on my eq so ive been either rolling the high end off or cutting the signal down with a distortion on its way into the pedal just to hear it properly. can you send me the schematics?. thank you very much.

  25. Great! thanks for the tip. Couldnt find the schematic online and this was a lot of help. I know somenthing wasnt right, now it sounds a lot better. If you have more schematic of this telray series please email me, i have a Volume Phaser Pedal too. Thanks a lot again

  26. I just picked up a pair of PWF’s: A clean later production one and perhaps a parts donor (missing chrome plating & bottom). Main question is: neither one has the box/shroud. Seems simple enough to make one from cardboard and cover w/ the black masking tape. Anything special to consider. Also planning to do the diode addition. Thanks.

    1. placement is the only thing to carefully consider. The original shrouds are literally cardboard and masking tape.

  27. Great post, thanks for sharing your experience!

    Just an FYI,

    My same model PWF had no diodes in place either, and by the looks of things, it came stock in this condition.
    I sourced 2 NOS 1N914b’s and A/B’d them in and out of circuit using alligator clips while looping a guitar riff, and man… they really made a huge difference!
    Much snarlier, I’m glad I put them in!

  28. Of note,

    C5 and C3 are originally rated for 64VDC, this will no longer do with today’s wall voltages. I’m reading 75V on one and 69V on the other, so I replaced them with caps rated for 100VDC. The rest of the ‘lytics are fine, reading voltage quite far below original spec recommendations.

    Cheers from Canada!

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