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SC682 and SC687 are the TD (toner density) sensor's own communication errors — a different component than the toner bottle ID chip covered in our SC681 guide, but closely related and using the exact same color-coding rule.
This fires when the TD sensor itself can't be reached after repeated retries. Ricoh's manual confirms the identical rule used for SC681:
And the same subtype ranges apply: 01–04 invalid device ID, 06–09 channel error, 11–14 device error, 16–19 communication interrupted, 21–24 communication timeout, 26–29 device stopped, 31–34 buffer full, 36–39 verification error.
Common causes: electrical noise, an incorrect or loose connection between the sensor and the Imaging IOB board, or in some subtypes, an actual sensor malfunction.
What to try: reseat the PCU (drum/developer unit) for the affected color, then check the connectors between the Imaging IOB board and the TD sensor. If that doesn't clear it, the harness, IOB board, or BICU board are the next things a technician would check, in that order.
This one is unrelated to color — it means the toner subsystem didn't receive an expected command from the controller. Ricoh's manual lists a refreshingly simple first step: detach and reattach the toner bottle. If that doesn't resolve it, the BICU board is the next thing to check.
SC687 is usually a free fix (just reseating a toner bottle). SC682 is a bit more involved than SC681 since it can point to the Imaging IOB or BICU board rather than just a toner bottle's ID chip — if it gets to that point, a technician's labor at around $350 per hour is worth weighing against a low-meter replacement on an older machine.
Not sure which way to go? Text us a photo of your error screen and tell us your model — we'll give you an honest read on whether it's worth fixing, no obligation. And if it makes more sense to replace it, we carry low-meter, fully tested copiers at wholesale liquidation pricing with free delivery and installation throughout Southern California, often available the same week.
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Need a replacement copier instead of a repair? Browse our color copier inventory at wholesale liquidation pricing.
