Riso Error A16-525 __top__ May 2026

If you are seeing Error A16-525 on your Risograph, the machine is essentially stuck "waiting for the master to be removed" from the print cylinder . This usually happens when the sensor detects a master still on the drum, even if you’ve already peeled it off. Why it happens The machine uses a light sensor to look at a small, non-reflective black velvet strip (the "light absorber strip") near the drum clamp. If it sees a reflection: It thinks there is a white master covering the strip. If it sees no reflection: It knows the drum is bare. If you are getting a "false" error, it’s usually because that black strip has become shiny from ink, is scrunched up, or is a thinner aftermarket version that isn't absorbing enough light. How to fix it The "Sharpie" Trick: Many users find that coloring the black velvet strip with a black permanent marker helps it absorb light better, clearing the error. Tape Fix: If the marker doesn't work, apply a small piece of black gaffer’s tape or matte black electrical tape over the strip to ensure zero reflection. Clean the Sensor: Sometimes ink mist gets on the master-detect sensor itself (usually located in the master disposal unit area). Gently wipe it with a lint-free cloth. Hardware Check: Inspect the white plastic wheels or gears on the side of the drum clamp; if one is missing or broken, the clamp may not be seating correctly for the sensor to read it. Reset Procedure: Try holding the yellow Reset button while turning the machine on to force a clear of the current state. For a visual walkthrough on resolving common drum and master errors like A16-525, this video can help: Riso 3230 A16 525 error resolve Creator Ratikanta YouTube• Mar 30, 2023 Are you using a generic replacement screen on this drum, or did the error start after a specific incident like a master jam?

The Riso error code A16-525 indicates that a master is stuck on the print drum or that the machine thinks one is present when it isn't . This usually happens when the master sensor cannot detect the drum's surface correctly. Common Fixes Remove Master Manually: If there is a master on the drum, pull out the print cylinder and peel the old master off by hand. Check the "Light Absorber" Strip: This is a black velvet or non-reflective strip on the drum. If it is dirty, worn, or "too fuzzy," the sensor may reflect light back and incorrectly report that a master is still present. Quick Hack: Covering the area with black gaffer's tape or washi tape can sometimes absorb the light enough to clear a false error. Clean the Master Sensor: Ink or dust on the sensor lens inside the machine can cause detection failures. Reset the Machine: Sometimes you must switch to a different drum, remove the master disposal box, and power the machine off and on to fully clear the error state. For a visual walkthrough of clearing this specific error on machines like the CV 3230, watch this troubleshooting guide: Riso 3230 A16 525 error resolve Creator Ratikanta YouTube• Mar 30, 2023 Advanced Troubleshooting If basic cleaning doesn't work, technical users on Reddit and Facebook suggest: Adjusting Drum Angle: Using test mode simulation 941 or 959 to adjust the "Position-A" angle so the sensor aligns better with the non-reflective strip. Aftermarket Screens: This error is common with generic replacement screens where the light-absorbing strip is thinner than the original part. If you'd like to try the test mode adjustments , could you tell me: Your specific machine model (e.g., EZ220, RZ200, CV3230)? If you recently replaced the screen or master roll?

Troubleshooting Guide: Decoding and Fixing RISO Error Code A16-525 If you are a print shop operator or a maintenance technician for a RISO high-speed inkjet printer (specifically the ComColor series like GD, GH, or GL models), seeing the error code A16-525 flash on your control panel is a moment that demands immediate, focused attention. This specific error is not a simple paper jam or an out-of-ink warning. It is a hardware-level stoppage related to the machine’s critical paper transport and registration system. In plain terms, RISO error A16-525 indicates a Timing Mismatch: Paper Position Sensor (PF Register Sensor) abnormality. When this error appears, the machine immediately halts all printing operations. Ignoring the cause or failing to reset the system properly can lead to damaged print heads, creased paper, or repeated mechanical failures. Let’s break down exactly what this error means, what causes it, and the step-by-step methods to clear it for good. What Does RISO Error A16-525 Actually Mean? To understand A16-525, you need a basic understanding of the RISO ComColor’s paper path. These machines run at speeds up to 150 pages per minute. To achieve that speed, timing is measured in milliseconds. The "A16" family of errors relates to the PF (Paper Feed) Drive Unit . The sub-code "525" points specifically to a Register Sensor timing failure . Here is the technical translation: The machine expects the leading edge of the paper to hit a specific optical sensor (the PF Register Sensor) at a precise moment during the feed cycle. When the CPU compares the actual sensor activation time against the calculated standard value, if the deviation exceeds the allowable range (usually ± a few milliseconds), the system throws error A16-525 . What the machine thinks: “I sent the paper. I waited for the sensor to trigger. The sensor did not trigger within the allowed window. Either the paper didn’t arrive, the sensor is lying, or the roller is slipping.” The Primary Culprits Behind A16-525 Before you panic and order expensive replacement parts, understand that this error is usually caused by three distinct issues. You must diagnose in the correct order. 1. The "False Positive" – Contaminated or Misaligned Sensor This is the most common cause. The PF Register Sensor is an optical device. Over time, paper dust, ink mist, and static-charged debris stick to the sensor lens. If the sensor is dirty, it cannot "see" the paper edge correctly.

Result: The sensor sends a late (or no) signal, causing the timing mismatch. riso error a16-525

2. The Mechanical Culprit – Worn or Glazed Paper Feed Rollers 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.

Result: The sensor triggers late, triggering the A16-525 alarm.

3. The Electrical Issue – Failing PF Drive Motor or Harness Less common, but more severe. If the PF (Paper Feed) motor is failing to maintain constant speed, or if the wiring harness to the register sensor has a micro-fracture, intermittent timing errors will occur. If you are seeing Error A16-525 on your

Result: Random occurrences of A16-525, often accompanied by clicking noises or erratic paper feed.

Step-by-Step Diagnosis and Fix (Do Not Reset First) Do not simply turn the machine off and on. That will temporarily clear the code, but it will return mid-run, wasting 50 sheets of paper. Follow this protocol: Step 1: Visual Inspection & Cleaning (Solves 70% of Cases)

Power off the machine and disconnect the main power (for 60 seconds to discharge capacitors). Open the front cover and the side paper transport unit. Locate the PF Register Sensor . (Consult your service manual; it is usually a small green or black PCB with a U-shaped optical slot, located just before the print head carriage). Using a lint-free swab and isopropyl alcohol (99%) , gently clean the inside of the U-shaped sensor slot. Using a can of compressed air, blow out the dust from the surrounding area. While the cover is open, manually rotate the PF rollers and wipe them with a damp cloth to remove glazing. If it sees a reflection: It thinks there

Step 2: The "Sensor Check" via Service Mode You need to verify the sensor is working electronically.

Enter Service Mode (Usually: Hold Stop + Start while turning on the power, or press Reset then Numeric 7 – check your specific model). Navigate to I/O Check Mode -> Input Check . Find the code for the PF Register Sensor . Place a piece of white paper at the sensor location. The display should toggle between "0" (no paper) and "1" (paper present). If the value does not change even after cleaning, replace the sensor.