Schemo for DOD 460 Mini Chorus?

[Joe Kramer]

Hey Friends,

Just got off the phone with DOD--they don't have any service papers for this one.    Anyone happen to have the schematic for it?  Thanks for any help!

Joe

[Shed_FX]

There is not much information out there on these. The schematic is certainly not about as i have looked many times. What do you need to know. I have two  , both in working order.

[Joe Kramer]

Hey Shed,

Thanks for the reply.  Two?  Lucky dog! 

Well, I've looked at gut shots here:

http://www.modezero.com/dod-460.htm

It seems as simple as can be, and a good candidate for DIY.  I'm thinking an MN3207 could be subbed for the SAD512 with a little hacking.  What's your opinion of the effect itself?  Would it be worth the effort to build?  There is at least one place on the web that sells a schemo ($15 I think), but I could probably reverse-engineer it given high-quality close-ups of both sides of the PCB.  Thanks for your thoughts.

[Shed_FX]

I think the pedals are great, thats why I got two! The second on is in mint condition with its original box and warranty card! 

Im not sure about modding the circuit with another chip, it could perhaps be done. But im not that experienced with these things. If you want to draw out a schem I can supply you with as many photos as you want but the second hand values of the pedals are really quite low (30quid) and would be difficult to justify the time. I'm going to be busy with cloning the Lovetone Doppelganger for quite a while so I won't be able to help.

I would say it could be a good fun project to do, and you are bound to learn loads doing it.

Any further help you might need let me know (I would like a schem too but never got round to it!)

[analogguru]

If you want to draw out a schem I can supply you with as many photos as you want...

Hmm....and where can I find this pictures ?

analogguru

P.S.: please don´t forget the track-side....

[Shed_FX]

I shall get my camera.....

[Joe Kramer]

Hey Shed,

Pix would be great of you!  One request on that subject: could you try and make the PCB shots as "square" and straight-on as possible?  That is, try to avoid the camera lense "bending" the edges of the board.  This way it will be easier to superimpose the top and bottom sides for tracing out.  Thanks!

[Shed_FX]

Right, I am afraid it is almost impossible to get a complete shot of the board square on as the pots are directly mounted to the board.I have bent them up and shot the layout underneath so it can be traced. If these pedals weren't working I wouldn't hesitate to remove the pots but I don't want to risk it on working units. The photo of the top shows all but one of the resistors (behind the 470 cap), for readable cap values I may have to wait and take a photo in daylight.

http://i123.photobucket.com/albums/o293/en1ltph/DSC00750.jpg
http://i123.photobucket.com/albums/o293/en1ltph/DSC00747.jpg
http://i123.photobucket.com/albums/o293/en1ltph/DSC00743.jpg
http://i123.photobucket.com/albums/o293/en1ltph/DSC00746.jpg

Enjoy

Let me know if there are any confusing bits and I can take more detailed photo's

[BMF Effects]

Here for $15.

[Joe Kramer]

Hey Shed,

Thanks so much for the pix!  You're right in hesitating to take apart the whole thing.  I'm not sure I can do an accurate job piecing those different angles together, but I'll try.  Otherwise, I'll just cough up the fifteen bucks and consider it "tuition." 

What's interesting to me about that 460 circuit is how they are getting a clock with so few components.  Only two op amps, and one of them is likely an LFO. . . .

Again, many many thanks!

Joe

[Shed_FX]

No problem mate, glad to be of service. I think with this forum the best way to think about it is learn what you can and give back what you can. It then all works out nicely. (Forum Karma I suppose).

Give me a shout if you need any more pix

Cheers

[Joe Kramer]

(Forum Karma I suppose).

Good Karma on you!   

[Mark Hammer]

Note that the 8-pin SAD512 takes in a single-phase clock pulse and does the division inside the chip.  This makes the production of the HF clock pulse a rather trivial matter, and the board that much smaller because of it.  The MN3207 needs two clock pulses, which necessitates use of the MN3102 or some other means of taking an LFO input and generating two complementary clock signals.

All of which leads me to say that trying to duplicate a DOD 460 using an MN3207 is most likely going to result in a different circuit, rather than an exact duplicate of the 460.  Better off to simply make yourself a CE-2 and dicker with clock range and tone-shaping.

[Joe Kramer]

Ah, good catch Mark!  I had looked at the 512/1024 datasheet without seeing any difference.  But now, from what you said and from looking again at Shed's pix, I see the 460 uses an SAD512D .  Big difference!  The use of only a single-phase clock would somewhat account for the scarcity of parts. 

I have to agree with you, it would be nearly starting from scratch to design a 3207/3102 into the 460.  I wouldn't be so intent on trying to duplicate the sound of the 460 (never even heard one), but the simplicity of the circuit seemed attractive.  At this point, I'll most likely revert to what I usually do, and venture into my own idiosyncratic "design."

Thanks.

[analogguru]

So, the schematic is traced, I need to draw it in the computer.  Missing some component values.  Nothing exciting, not even an input filter. Only power supply filtering is professional.

Input-buffer with preemphasis => bbd-delay-line => 18db/octave Low-Pass-Filter => mixer/deemphasis/outputdriver.

Not even worth to think about to make a copy. Even an Ibanez CS-5 will be better.
So buy an Ibanez CS-5, Boss CE-2, Psk SCR-2 or Rogue SCR-5, Arion SCH-1/SCH-Z on evil-bay and rehouse it.  If you need a muddy-chorus sound like this unit change the output filter (3 resistors/3 capacitors).

Wil post tomorrow a picture of the missing component values.

analogguru

[MartyMart]

Gottfried, agreed - the Arion is a cracker - just the plastic case and pots/jacks let it
down !
For a modern cheap but GREAT chorus, try the little Dano FAB - real good for £13.99 !!
I still love my DIY CE-2, but best chorus is my old Pearl chorus, with balance and tone
control !    = instant vibrato mode !

MM.

[StephenGiles]

I never could understand why balance controls where not included on chorus pedals - probably a marketing decision!!

[MartyMart]

I never could understand why balance controls where not included on chorus pedals - probably a marketing decision!!

Well, it's just one more pot and a couple of parts ... what's that £1.50  !!
I'd be happy to pay an extra £5 for a unit with balance/tone pot

[StephenGiles]

Perhaps it's their standard small box that prevents it.

[MartyMart]

Perhaps it's their standard small box that prevents it.

Zvex would not agree with that !!!