If you see a crumpled or partially fed master sheet, gently pull it out in the direction of the normal paper path to avoid tearing.
Before you begin, ensure the machine is turned off and unplugged to prevent any accidental electrical shocks or mechanical movements.
If the error occurs on a bare drum, the light absorber strip is the primary culprit. riso error a16-525
If cleaning fails, more advanced solutions are required. Replacing the feed tires and separation pad is a standard, low-cost procedure that restores mechanical reliability. In cases where the error occurs only when printing on heavy stock (e.g., cardstock), adjusting the "paper thickness" dial or lever to a heavier setting changes the pressure between the feed roller and separation pad, allowing thicker media to pass. For persistent sensor errors after cleaning, a sensor test mode exists within the Riso’s service menu. Entering this mode (often via a specific key sequence) allows the user to wave a piece of paper in front of sensor 525 while the machine is idle; if the display does not change state, the sensor is electrically dead and requires replacement by a certified technician. Attempting to bypass or ignore the A16-525 code—by repeatedly pressing the reset button—is counterproductive. It will only lead to crumpled masters, ink on the pressure roller, or costly damage to the drum’s mesh.
Try holding the yellow Reset button while turning the machine on to force a clear of the current state. If you see a crumpled or partially fed
Some models use simulation 941 (40 or -40) for drum position adjustment. Summary of Actionable Steps Pull out drum, check for stuck plastic. Remove physical obstruction. 2 Clean drum and sensor with alcohol. Remove ink buildup causing false readings. 3 Power cycle the machine. Reset the error state. 4 Check/reset master disposal box. Ensures the disposal mechanism is aligned. 5 Test with a different drum. Isolates if the problem is the machine or a specific drum.
Do you see a inside, or is the path clear? Share public link If cleaning fails, more advanced solutions are required
Look inside the empty box to ensure no loose master sheets are stuck to the bottom or sides.