Bought a weirdo Yamaha overdrive that operates on MOSFET chips

[Rambozo96]

I was bored on Buyee which is an auction site for vendors in Japan and come across this Yamaha COD-100 overdrive from the late 80’s best as I could tell. For a whopping $28 (and just as much for shipping D’oh.) I thought I’d take a chance on it so see what it could do given it’s a weirdo pedal that’s not really a clone of anything that I’m aware of. I bought the service manual so I could look into it more in depth but as far as I can tell the MOSFET does the overdrive sounds like in a Red Llama/Craig Anderton Tube Fuzz with a NE571 chip that acts as a compressor. I guess it was one of many attempts back then to simulate a overdriven tube the compression characteristics.

 

[Default]

I have parts to build a few of those.

 

[Rambozo96]

I

I have parts to build a few of those.

think I have some of the CMOS chips it called for. I don’t know where you would source a NE571 these days

 

[Rambozo96]

https://www.mouser.com/ProductDetail/ON-Semiconductor/SA571DR2G?qs=xZq1yRCsb1eAAE0c55WTtQ==. If one wasn’t afraid of an SMD route

 

[Default]

cd4049

https://www.newark.com/texas-instruments/cd4049ube/inverting-buffer-hex-4000-cmos/dp/33AH3799?gclid=Cj0KCQjwkZiFBhD9ARIsAGxFX8AuNYRN-JPtI8SHktqpYL8zz_v0o-VqDMk7zurRfmyQolllnJFklD0aAjBSEALw_wcB&mckv=sycAQPVwf_dc|pcrid|506882751582|plid||kword||match||slid||product|33AH3799|pgrid|122273150391|ptaid|pla-1199378040224|&CMP=KNC-GUSA-GEN-Shopping-VeryLow-Semis

 

[Default]

Zen Cart!, The Art of E-commerce

Zen Cart! : - Switches Grab Bags Parts T-Shirts Boards Specials Shipping Additions Capacitors IC Jacks Transistors Diodes Power Sockets Resistors Wah Parts Tubes Kits iPad Hardware and Software Special Category Merchandise ecommerce, open source, shop, online shopping, store

www.diystompboxes.com

 

[Default]

tonepad -- FX projects

 

[JohnW63]

Sell it to Josh at JHS Pedals! He is a huge collector of guitar pedals as well as a builder of them. Of course, seeing how many odd and rare pedals he has, he might have one " Mint. In Box " .

 

[SFIV1967]

I don’t know where you would source a NE571 these days

Lot's of sources around the globe when you Google "ne571 ic".
Ralf

 

[Rambozo96]

From what I could see of the grainy auction pics of the service manual I see they label it as a compander so I guess maybe it’s for noise reduction like how these chips are used with modulation effects to cut down on hiss.

 

[Guildedagain]

I love MOSFET overdrives.

 

[Rambozo96]

I love MOSFET overdrives.

I remember I had the original EHX Hot Tubes distortion that was probably the main part of my tone when I ran an old Yamaha SS amp. Unfortunately it bit the dust when I knew somewhere between jack and squat about pedals so it sold for almost nothing. Been meaning to finish the clone I ordered a PCB for. Will probably be more practical because I remember that Hot Tubes using a unwieldy mains voltage plug. I need to dredge that project up and finish it. I think I bought that PCB like 2 years ago and have it 90% finished

 

[Rambozo96]

Also given the Craig Anderton Tube Fuzz (The Way Huge Red Llama is the modern day commercially available version.) was my first crack at DIY from the ground up with just a schematic and vero board

 

[Default]

Same here. I sent my original EH Hot Tubes to EHman to get repaired. My buddy has that and a TSF that I built for him. Now both need work, but I bought 4 boards, so things will be getting fuzzy around here...

 

[Rambozo96]

Some people rag on the reissue but I thought they were pretty close to the original I owned and made to fit a pedalboard much better. Many forget that EHX had some inconsistencies with parts values. When they ran out of a cap or resistor sometimes they used substitutions.

 

[Default]

I own the reissue too. Some folks think that it lacks character, but it does what it's supposed to do pretty well.

 

[Default]

Some people rag on the reissue but I thought they were pretty close to the original I owned and made to fit a pedalboard much better. Many forget that EHX had some inconsistencies with parts values. When they ran out of a cap or resistor sometimes they used substitutions.

Not that Guild would ever do that!

 

[jp]

Also given the Craig Anderton Tube Fuzz (The Way Huge Red Llama is the modern day commercially available version.) was my first crack at DIY from the ground up with just a schematic and vero board

Man, I still have my tattered copy of his book from my youth. I haven't touched it in years, but I should.

 

[Rambozo96]

The schematic from the service manual has arrived

 

[Rambozo96]

It arrived today, not high gain by any means but in a world full of DS-1’s and HM-2 clones that’s not a bad thing. The EQ knobs oddly enough increase the gain when turned up at the expense of tonal weirdness if turned all the way up. I think where it really shines is stacked with other OD’s or as a boost to drive another distortion pedal for a lead sound much like some do with a tubescreamer. I should probably do a proper test as this is with a SS Yamaha PG-1 preamp through cheap earphones. Through a typical amp set up may yield different results but that will have to wait as my old Mogami cable I used since 2015 seemed to have finally crapped out on me. The culprit is the ground wire breaking loose so totally salvageable and not the first time I had to do this repair.