DOD - 670 Flanger  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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ilcaccillo
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Post by ilcaccillo »

Hi,
I'm repairing at the moment a DOD 670 flanger that has what seems to be a shot SAD512D delay chip.

My pedal has a 110V power input, as I live in Europe and while I'm waiting to solve the current SAD512D situation I'm thinking in replacing the original small 110V primary power transformer for a 230V transformer so I don't need a mains voltage converter.

Just to let you know, theres versions of this pedal where the power transformer has 110V and 220V volts taps on the primary (the available schematic reflects this models), so those can be easilly rewired of operations as needed on both sides of the Atlantic, thats not the case with the unit I own, where the power transformer primary only has 2 red wires for 110v operation.

The circuit needs to see 15V that are regulated with the use of an 7815 regulator. They only used halfwave rectification so a 36V output secondary transformer was used.
Could I change in this circuit the rectification for a full wave rectifier so that I only need to use a transformer with an 15VAC secondary ?
After rectification the 15VAC will be aprox. 21VDC more than what the 7815 needs to regulate

Im asking this because I dont know if theres any reason circuit wise for the use of an half wave rectifier instead of a full wave one,
would the flanging circuit work the same way guaranteeing you are supplying filtered and regulated 15V?

Schematic attached

Thank you
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DOD 670 Flanger - schematic.pdf
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CheapPedalCollector
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Post by CheapPedalCollector »

I recently repaired two of these from my own collection, thanks to a post on that other forum by Fender3D.

I have cleaned up and corrected the schematic, posting here as well for others who may need it.

To reiterate, if you have distortion or other issues replace all the electrolytic caps, 16V caps are not high enough voltage for these pedals. I replaced them all with Nichicon 25v rated caps, and the .47uf caps with 100V film ones. It's not the SAD512 most likely.
DODFlanger670.PNG

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ppluis0
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Post by ppluis0 »

Hi there,

There is an interesting way to enable/disable the operation of flangers and also chorus and other things that incorporates NE571 companders.
In several DOD designs the effect is silenced by means to pull the pin 16 to ground (or pin 1 if the sections are reversed) in order to mute the expander stage as can be seen in the previous diagram and also in the following schematic:

Image

Cheers,
Jose

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