Konica Minolta bizhub Original detected but scan does not start – Troubleshooting Guide

A particularly frustrating problem on Konica Minolta bizhub multifunction devices is when the machine clearly detects that an original is present — whether on the flatbed glass or in the ADF — but the scan operation never actually starts. You press the Scan button, but nothing happens. No carriage movement, no document feeding, no image captured. The machine simply sits idle, or in some cases, the scan process appears to begin but freezes immediately.

This problem can arise from a wide range of causes: simple configuration errors, faulty sensors, failed scanner motors, broken drive gears, corrupted firmware, or even authentication issues. This guide provides a systematic approach to diagnose and resolve scanning start failures, from the simplest user checks to advanced hardware replacement procedures.

Possible Causes

Blocked or dirty original detection sensor (ADF or flatbed)
Scanner carriage cannot move — locked by transport lock, foreign object, or mechanical obstruction
Failed scanner home position sensor (PS201 or equivalent)
Failed scanner motor (M201/M100) or scanner drive board (SCDB)
Broken scanner drive gear, belt, or pulley
Corrupted firmware or software glitch on the MFP board (MFPB)
Incorrect scan settings (e.g., authentication unit connected but not configured)
Connection issues: flatbed scanner cable disconnected or ADF cable faulty
Paper jam remnants inside the scanning unit obstructing carriage movement
Faulty CCD unit or CIS module unable to acquire image data
Memory or data bus failure preventing image transfer
C-8104 glass movement failure — dustproof seal turned over or paper jam remnant in the scanning 1st reverse section

Step‑by‑Step Troubleshooting

⚠ Important Safety Notice: Before performing any internal inspection, turn off the main power switch, unplug the machine from the wall outlet, and allow the fuser unit to cool completely.

Step 1 – Basic User Checks

Start with the simplest user‑level verification:

Verify that the document is placed correctly — original glass originals should be face down, aligned with the reference scale. ADF documents should be face up and securely loaded within the capacity limits.
Check that the ADF or original glass cover is fully closed. An open cover will prevent scanning from starting.
Ensure the document meets specifications — not too thin, not too small, not wrinkled or folded.
Confirm that the machine is not in Power Save mode. Wake the machine by pressing the Power Save button before attempting to scan.
Check that no error messages or service call codes are displayed on the control panel. If any are present, note the trouble code and address it first.

Result: If the machine scans properly after basic checks, the problem was user error. If not, proceed to Step 2.

Step 2 – Check Network or USB Connections (Network Scan Users)

If scanning to a computer via network or USB, connection problems can prevent the scan from initiating:

Turn the machine OFF and check that the USB cable and network cable are connected correctly.
If the USB cable and network cable connections are found to be in order, turn the machine ON again.
Restart the computer — a temporary communication issue may be resolved by a simple reboot.
If the problem persists, uninstall and reinstall the TWAIN driver or the scanning software on the computer.

Step 3 – Check Scanner Lock and Mechanical Obstructions

If the scanner carriage cannot move, the scan operation will never start:

Power off the machine. Locate the scanner lock lever (usually on the back or bottom of the machine). Ensure the lock is in the UNLOCKED position — a locked scanner is a frequent cause of scanning failure after machine relocation.
Manually attempt to slide the scanner carriage (if accessible). It should move smoothly with slight resistance. If it feels stuck or grinds, there is a mechanical problem.
Inspect the scanning glass area for any foreign objects — paper clips, staples, or small debris — that might block carriage movement.
Check for paper jam remnants inside the scanning unit. On certain models (C451, C550, C650), when a jam occurs in the ADF, the scanning 1st reverse section lacks a paper detection sensor. The machine may start normally, but the trailing edge of a remaining original can get stuck between the scooping guide and the scanning glass, preventing the glass from returning to home position and displaying C-8104.

Step 4 – Inspect the Scanner Home Position Sensor

The scanner home sensor (PS201 or equivalent on most models) tells the machine where the scanner carriage is located. If this sensor fails, the machine cannot begin a scan job. Error codes such as C6102 (drive system home sensor malfunction) or C6103 (slider over‑running) indicate home sensor issues.

Enter Service Mode (refer to service manual for your model).
Navigate to [State Confirmation] > [Sensor Check].
Locate the scanner home sensor in the sensor list.
Manually move the scanner carriage away from the home position and back. The sensor status should change from “Blocked” to “Unblocked” (or vice versa). If no change occurs, the sensor is faulty.
If the sensor status changes but scanning still does not start, the problem may be the scanner motor, drive gear, or control board.
Check the connector between PS201 and SCDB (or directly to MFPB depending on model) for proper connection and correct as necessary.

Step 5 – Test the Scanner Motor (M201/M100) and Drive Train

A failed scanner motor or broken drive gear will prevent the scanner carriage from moving, even if the home sensor is functional:

Enter Service Mode and navigate to [State Confirmation] > [Load Check].
Activate the scanner motor (M201 or equivalent) and listen for motor rotation and carriage movement.
If the motor runs but the carriage does not move, inspect the scanner drive belt, pulley, and gears for damage or looseness.
If the motor does not run, check the connector between M201 and SCDB (or MFPB) for proper connection and correct as necessary.
If the connector is good and the motor still does not run, replace the scanner motor.
If the motor runs but scanning still does not start, check the scanner drive board (SCDB) — it converts control signals from the main board to drive the motor and read the home sensor.

Step 6 – Perform Memory Bus Check (C6704 Image Input Time Out)

If the machine displays error C6704 (image input timeout), image data is not being transferred from the scanner to the MFP board:

Enter Service Mode.
Navigate to [State Confirmation] > [Memory/Storage Adjustment] > [Memory Bus Check].
Select [Scanner → Memory] and execute the test. The machine will scan and write test data to memory.
If the memory bus test fails, check the connector between the scanner unit and the MFP board.
If the connection is good, replace the scanner unit. If the problem persists, replace the MFP board.

Step 7 – Clean the Scanner Home Sensor and Carriage Path

Dirt, dust, or toner particles can block the home sensor or interfere with carriage movement:

Power off and unplug the machine.
Remove the scanner unit covers (refer to service manual for your model).
Locate the scanner home sensor (typically a photo-interrupter near one end of the scanner rail). Use compressed air or a soft brush to remove any dust or debris from the sensor.
Clean the scanner rail and the carriage contact area with a lint-free cloth. Avoid using liquids that could damage the sensor.
If the dustproof seal on the DF original glass moving unit has turned over, clean the area with alcohol and reseat the seal. On certain models, a turned-over dustproof seal can contact surrounding parts, increasing sliding load and triggering C-8104 (glass movement failure).

Step 8 – Check ADF Detection and Feeding

If using the ADF, the machine may detect the presence of paper but fail to start feeding:

Check that the ADF cover is completely closed. An open cover prevents scanning from starting.
Inspect the ADF paper present actuator — it may be stuck in the “paper present” position due to dirt or a broken spring.
Enter Service Mode and navigate to [State Confirmation] > [Sensor Check] to test ADF sensors (document front sensor, registration sensor, etc.).
If sensors are working but paper does not feed, perform ADF motor tests via Service Mode load checks.
Check the ADF cable connection — both at the ADF relay board and at the main controller board (often labeled JADF1). Pins 14 and 16 should measure +24VDC; pins 15 and 22 should measure +3.3VDC.
If the ADF motor runs but the feed roller does not rotate, inspect the feed roller holder assembly for damage.
If all else fails, the ADF unit or ADF control board (DFCB) may need replacement.

Step 9 – Check Authentication and Scan Settings

On machines with authentication units (fingerprint scanners, card readers), scanning may not start if authentication fails:

If an authentication unit is connected, verify that it is configured correctly in the machine settings.
Check that the finger is correctly positioned on the authentication unit — improper placement is a common cause of scanning failure.
Restart the machine after connecting the authentication unit to ensure proper initialization.
If scanning to email or network folder is failing, verify SMTP server settings, destination address, and file size limits. Large attachments may exceed server capacity, causing the scan to abort before starting.

Step 10 – Service Mode Adjustments

If hardware appears functional but scanning still does not start, adjustment parameters may be incorrect:

Enter Service Mode → [System 2] → [ADF Settings]. Verify that the installed ADF type matches the machine configuration.
Navigate to [Service Mode] → [Machine] → [Scan Area] to adjust image position and scan area boundaries. Incorrect settings can cause the machine to abort scanning.
If performing a firmware update via USB or network, verify that the firmware file is correct for your model. Corrupted firmware update can cause the MFP board to fail to initialize the scanner.

Error Codes Associated with Scan Start Failures

When scanning fails to start, the machine may log one of the following service codes:

C6102: Drive system home sensor malfunction. The scanner home sensor (PS201) is unable to detect the scanner located at its home position, even after the scanner motor has been driven over the maximum traveling distance.
C6103: Slider over‑running. The scanner home sensor detects the scanner at its home position during a period of time that begins with the execution of a prescan command and ends when a home return command is executed.
C6106: ADF back side CIS home sensor failure. The ADF back side CIS unit cannot return to the home position — common on dual‑scan ADF models.
C6704: Image input time out. Image data is not input from the scanner to the MFP board (MFPB). Perform memory bus check and inspect scanner to MFPB connector.
C6751: Light adjustment failure. During light adjustment, the peak value of output data remains at or below 64 for three consecutive retries. Usually indicates a failed CIS module or extraneous light entering the scanner.
C-8104: Glass movement failure (older models like C451/C550/C650). DF original glass moving in IR unit does not move properly — often caused by a turned‑over dustproof seal or remaining paper jam in the scanning 1st reverse section.
C6001/C6002: DF related configuration errors. Inconsistency in the configuration with the installed DF is detected on the main body. Check ADF Settings in Service Mode.

Summary Diagnostic Table

Symptom	Most Likely Cause	Action
Original detected on glass but scan does not start; no carriage movement	Scanner transport lock engaged; scanner home sensor failure	Unlock scanner lock; check home sensor (PS201); replace if faulty
ADF detects paper but does not feed; scan never begins	Stuck ADF paper present actuator; failed ADF motor; ADF cable disconnected	Clean sensor actuators; perform ADF motor test; check JADF1 connector voltage
Machine displays C6102 or C6103 error code	Scanner home sensor (PS201) malfunction; drive belt or gear damage	Check PS201 connector and signal; inspect scanner drive belt, pulley, gears; replace SCDB or scanner unit
Machine displays C6704 error	Image data not transferred from scanner to MFP board	Perform memory bus check; check scanner-to-MFPB connector; replace scanner unit or MFPB
Scanning works occasionally but freezes at random	Loose connector; corrupted firmware; failing MFP board	Reseat all scanner-related connectors; update firmware; replace MFPB if problem persists
C-8104 displayed (C451/C550/C650 series)	Dustproof seal turned over; paper jam remnant in scanning 1st reverse section	Clean area with alcohol and reseal; remove any remaining paper in the scanning reverse section
Scan to email or network folder does not start; no error code	SMTP server configuration error; authentication unit improperly placed; file size too large	Verify SMTP settings; check finger placement on authentication unit; reduce attachment size

Flatbed vs. ADF Troubleshooting Quick Reference

Original glass scanning failures:

Check that the original glass cover is closed — the flatbed may not scan if the cover is open.
Verify that the scanner carriage moves freely — remove any debris from the glass edges.
Clean the original glass and the shading sheet — dirt can cause the machine to abort scanning prematurely.
Adjust the scanning start position via Service Mode → [Machine] → [Scan Area] → [Image Position: Leading Edge].

ADF scanning failures:

Ensure the document is loaded face up, not exceeding the paper capacity indicator.
Check that the ADF cover is firmly closed — if the cover is even slightly open, scanning will not start.
Clean the ADF separation roller and feed roller — worn or dirty rollers may not feed paper.
Inspect the ADF original pad and CIS glass for dirt or damage.
If the ADF motor runs but the rollers do not turn, the feed roller holder assembly may be broken — replace the assembly.

When to Call a Certified Technician

While basic checks (cable connections, scanner lock, sensor cleaning) can be performed by any user, the following tasks require a certified Konica Minolta technician:

Replacing the scanner motor (M201/M100) or scanner drive board (SCDB)
Disassembling the scanner unit to access the home sensor or drive belt
Replacing the MFP board (MFPB) or CPU board (CPUB)
Performing advanced adjustments in Service Mode beyond basic sensor checks
Flashing firmware when the machine is unresponsive to normal update procedures
Replacing the CCD unit or CIS module
Any repair requiring the machine to be powered on with covers removed

Attempting these repairs without proper training and documentation may lead to further component damage, loss of calibration data, or electrical shock hazards.

Conclusion

A Konica Minolta bizhub that detects an original but refuses to scan can be a perplexing problem, but it is almost always solvable with a systematic approach. Start with the simplest external checks — scanner lock, cover closed, authentication unit — then move inward to sensor tests, motor checks, and memory diagnostics. Error codes like C6102, C6103, C6704, and C-8104 provide clear starting points for hardware‑level diagnostics. Most importantly, never assume the scanner is dead without verifying the mechanical and electrical components step by step.

By following this guide, you can identify whether the issue is a simple user error, a failed sensor or motor, a network configuration problem, or a more complex board failure — and take the appropriate corrective action to restore scanning functionality.