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When a scanner or copier produces all-black, it means (provided that devices is also printing normally, when sent a print job from a computer) that the scanner electronics has failed in some fashion.
Does the scanner bar still light up, with a very bright greenish-white or bluish-white light, and move to and fro under the glass, when you do a photocopy?
Or does it just move and not light up? that is what most commonly causes the 'black photocopy' phenomenon.... the scanner bar's 'bulb' burning out.
But also the sensor that 'reads' off the reflection from the document being scanned, from the light cast on it by the 'bulb', can also go bad, though that's slightly less common.
Have you tested by sending a print job from a computer to the Ricoh machine, also?