Error A16-525 — Riso

The sensor fails to see the "black" area of the drum, assuming a master is still covering it.

: If the drum's "Position-A" is slightly off, the sensor may look at the wrong part of the drum (like the metal surface) instead of the black absorber strip. Troubleshooting and Fixes 1. Immediate Physical Check riso error a16-525

Try holding the yellow Reset button while turning the machine on to force a clear of the current state. The sensor fails to see the "black" area

RISO rollers are made of a special rubber compound. After hundreds of thousands of prints, this rubber hardens or glazes over. If the paper feed roller slips—even by a millimeter—the paper arrives late at the register sensor. Immediate Physical Check Try holding the yellow Reset

Warning: Attempting to disassemble the PF drive unit without the service manual can knock the main timing off permanently, leading to costly head strikes.

Open the machine and manually peel the master off the drum if it's still there. Ensure the disposal box is empty.

The Riso error code indicates the machine is "Waiting for the master to be removed" from the print cylinder (drum). This error typically occurs when the printer's sensor fails to detect that a master has been successfully ejected into the disposal box. Common Causes