Riso Error A16-525 -

Check the print drum for proper alignment and ensure it is not damaged. Consult the machine's manual for instructions on how to check and adjust the drum.

If you have replaced an empty cartridge with a new one and the error persists, the machine may not have recognized the swap.

Use this if you found a PDF or website that helped you solve it.

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Review: "If you are getting the A16-525 code, do yourself a favor and download this guide. The official documentation was vague, but this manual walked me through the drum motor diagnostics step-by-step. I was able to clear the jam and reset the machine in under 20 minutes. A lifesaver for anyone managing their own Riso maintenance."

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.

If you are using a refilled cartridge:

The Riso Error A16-525 is a common technical issue encountered by users of Risograph digital duplicators, specifically within the Riso RZ Series, EZ Series, and RV Series.

Officially, the error description is "Waiting for the master to be removed from the print cylinder (drum)". This means the machine’s internal sensors believe a used master film is still attached to the drum and must be cleared before it can create a new one. Primary Causes of Error A16-525

While the machine may simply be waiting for a physical master to be removed, this error frequently occurs as a "false" reading even when the drum appears empty.

Residual Master Film: A piece of the previous master is still physically stuck on the drum or caught in the master clamp.

Sensor Misreading (Dirty Sensor): The master-on-drum sensor is dirty or blocked by ink/dust, leading it to signal that a master is present when it isn't. riso error a16-525

Reflective Strip Issues: Risograph machines use a small black velvet light-absorber strip (part number 023-17004) to detect the presence of a master. If this strip is worn, dusty, or replaced with a non-original version, light reflects off the drum surface, causing a false positive.

Aftermarket Screen Issues: Generic or third-party silk screens often use materials that are more reflective than original Riso screens, confusing the optical sensor.

Hardware Malfunctions: Broken transfer belts in the master disposal unit or a bent master clamp can prevent the machine from successfully stripping the master, triggering the code. How to Fix Riso Error A16-525 1. Basic Manual Reset

The first step is to follow the machine's standard clearing procedure: Pull out the print drum from the machine. Manually remove any master film wrapped around the drum. Re-insert the drum and press the [START] or [RESET] key. 2. Cleaning the Sensors

If the error persists with an empty drum, clean the optical sensors:

Locate the master detection sensor (usually situated above the drum area) and wipe it gently with a soft, lint-free cloth.

Clean the black velvet strip on the drum. Use a dry cloth or a slightly damp one to remove paper dust or ink buildup that might be making it reflective. 3. The "Black Marker" or Tape Trick

If you are using an aftermarket screen and getting a false error, the sensor may be seeing the light-colored mesh through the velvet strip.

Darken the strip: Use a black permanent marker to go over the velvet strip to ensure it absorbs as much light as possible.

Use Matte Tape: Some users find success by placing a small piece of black matte paper tape (like gaffer tape or electrical tape) over the strip to eliminate reflections. 4. Technical & Service Mode Adjustments

For advanced users, specific service parameters can sometimes resolve persistent errors related to drum positioning or sensor sensitivity:

Drum Angle Adjustment: If the drum isn't stopping at the exact right angle, the sensor may be looking at the metal body instead of the velvet strip. In Test Mode, Simulation 941 (Position-A adjustment) or Simulation 942 can be used to tweak the drum angle.

Master Clamp Adjustment: Use Simulation 543 to adjust the master clamp tension if the master is frequently failing to eject.

Reset Test Mode: You can attempt to reset the machine's parameters to default using Simulation 117. Troubleshooting Table Check the print drum for proper alignment and

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

Essentially, the machine thinks there is still a used master wrapped around the drum and won't let you create a new one until it’s gone. But what do you do when the drum is clearly empty? Here is how to diagnose and fix it. 1. The "Quick Reset" (Try This First) Use this if you found a PDF or

Sometimes the machine just needs a nudge to realize the drum is clear.

Manual Removal: Pull the drum out and double-check the "clamp" area (the long silver bar that holds the master). If a tiny scrap of master paper is stuck under the clamp or near the sensors, it will trigger the error.

Power Cycle: Turn the machine off, remove the master disposal box, wait 10 seconds, and turn it back on. 2. Check the "Light Absorber Strip"

This is the most common cause for a "false" A16-525 error, especially if you recently replaced your drum screen.

How it works: The Riso shines a light at a small black velvet strip on the drum.

Reflection = Master Present: Light reflects off the white master paper.

No Reflection = Drum Empty: Light is absorbed by the black velvet.

The Fix: If the velvet is dusty, worn, or scrunched up, the sensor sees a reflection from the metal/mesh underneath and thinks a master is present.

Clean it: Wipe the black strip with a dry, lint-free cloth to remove paper dust.

The "Sharpie" Trick: If the strip is faded, many users have success carefully coloring it with a black permanent marker or covering it with a small piece of black matte paper tape (like gaffer tape) to ensure it absorbs the sensor's light.

Hi riso community ! I've got a A16-525 error on one of my drums but the

Verify that the toner or ink levels are adequate and that they are correctly installed. Replace or refill as necessary.

You are a competent operator, but some repairs are beyond user level. Call a professional if:

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