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Vintage threads from the first ten years

Re: Boss DM2 schematic

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12/3/1997 10:12 AM

Re: Boss DM2 schematic

The plug end is the same, the power it puts out is somehow different, I forget how. My manual for the dm-2 says it takes an ACA 120 power supply and when I tried a newer one it didn't work right. I read about the different supplies on Harmony Centrals efffect data base I think. Sometimes the LED doesn't light up and the effect sounds fine, sometiomes the effect works fine in by pass and is distorted when activated, or doesn't workk at all with the new supplies.

12/4/1997 1:56 PM

CJ:

I don't know the specific difference between the two supplies referred to here, but I witnessed a related instance with a Boss pedal.

Some of the electronics hobbyist supply catalogs offer various "wall wart" type power adapters at great prices. So I bought some rated at 9volts, 300ma. (Why pay $10-$20 for an adapter, right?) When I connected it to an RV-3 pedal, hit the footswitch, the red light would come on but no sound would come through. Footswitched it off, the light went out, but it was still locked up.

Apparently what happened was the adapter's transformer had very poor regulation (I measured the open circuit voltage at about 12volts). The current draw from the pedal wasn't enough to keep the voltage near the 9v required by the pedal. My guess is the overvoltage latched one or more of the IC's, but I'm not certain. Some pedals may be sensitive to supply voltage.

Doc

12/5/1997 7:14 AM

Doc
I assume the polarity of the tip was correct? Boss and various other FX mfg's are backward from the rest of the world.
Most of these analog pedals will run on voltages above +9v. I cannot understand why +12v should not run the pedal. Now maybe 300ma was not enough for the pedal and the pedal sucked hard on the wall wart? That would draw the voltage down.
Please don't think I am questioning your ability or not beleiving your experience, I am just trying to gather more info .

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