Paper Jams July 25, 2026 by Editor Team

Konica Minolta bizhub — Paper Jam Code 14-40: Tray 4 Image Write Signal Timeout 

Paper Jam Code 14-40 is a Tray 4 image write signal timeout on Konica Minolta bizhub machines. Konica Minolta service documentation classifies all 14-xx codes under the heading Misfeed at Tray 4 Feed Section — a category label covering every fault type that originates in the Tray 4 paper source. However, the -40 suffix carries a precise and unambiguous meaning that is entirely distinct from a mechanical misfeed: the paper did not fail to feed. The paper fed correctly from Tray 4, travelled through the entire paper path, and arrived at the registration sensor on time. The fault is that the image write start signal permission (WTEN) — the board-level authorization that releases the paper from the registration nip into the imaging zone — was not issued within the specified timing window after that arrival.

The official Konica Minolta description states precisely:

For paper fed from Tray 4, the image write start signal permission (WTEN) was not issued within the specified time after paper arrival at the registration sensor.

Translated into field language: Tray 4 paper successfully fed from the fourth paper cassette, travelled upward through the Tray 4 unit’s transport section, passed through the Tray 3 LCT unit’s vertical transport section as a pass-through, continued through the base machine lower vertical transport section, and arrived at the registration sensor (PS1, PS9, or PS4 depending on model) within the required timing window. The machine confirmed paper presence at the registration area. However, the multi-board synchronization sequence that must then occur — the handshake between the print controller (CPUB), the primary engine board, any LCT sub-board or sub-boards in the communication chain, and the imaging section — did not complete within the programmed timeout period. The machine held the Tray 4 paper stationary at the registration roller nip, waiting for the write-enable signal that would authorize the registration clutch to drive the paper into the print zone. That signal did not arrive in time. The machine recorded 14-40 and abandoned the transport sequence.

14-01 and 14-02 are mechanical paper transport failures — the paper either never left Tray 4, or moved but arrived at the registration area too late. 14-40 is a board-level synchronization failure — the paper moved correctly and arrived on time, but the imaging system failed to authorize its entry into the print zone within the permitted window. Replacing any Tray 4 mechanical component will not resolve 14-40.

14-40 carries the greatest diagnostic complexity of any tray-sourced -40 code in the bizhub code family, for two compounding reasons. First, unlike Tray 1 and Tray 2 which are built into the base machine, and unlike Tray 3 which may be built-in or optional depending on model, Tray 4 is always an optional lower cassette unit on every bizhub configuration. There is no bizhub model with a factory-built Tray 4. This means the LCT sub-board (DCSB / OACB / equivalent) architecture that applies conditionally to Tray 3 applies unconditionally to Tray 4 — there is always a dedicated optional-unit sub-board in the Tray 4 communication chain, and it is always the primary hardware suspect when 14-40 fires in isolation.

Second, and unique to Tray 4, bizhub installations support two distinct optional-unit hardware configurations for Tray 4, each with a different communication chain topology and a different diagnostic approach:

  • Configuration A — Dual-cassette single LCT unit: A single optional lower cassette cabinet (such as a dual-drawer PF unit) contains both Tray 3 and Tray 4 cassettes and is served by a single DCSB or OACB sub-board that manages both tray feed sequences and reports both tray paper positions to the primary engine board. In this configuration, a failed DCSB produces both 13-40 and 14-40 simultaneously, because the single sub-board serves both tray feeds. A 13-40 + 14-40 pattern with Trays 1 and 2 printing normally is the diagnostic signature of this configuration’s sub-board or shared harness failure
  • Configuration B — Stacked dual LCT units: Two separate optional lower cassette units are stacked vertically, with the Tray 3 LCT unit above the Tray 4 LCT unit. Each unit has its own independent DCSB or OACB sub-board. The two sub-boards are connected in one of two topologies: daisy-chain (Tray 4 DCSB communicates to Tray 3 DCSB, which communicates to the base machine engine board) or parallel (each DCSB communicates independently to the base machine via its own harness). In daisy-chain topology, a failed Tray 4 DCSB or Tray 4 DCSB harness produces isolated 14-40; a failed Tray 3 DCSB or the shared harness from Tray 3 DCSB to the base machine engine board produces both 13-40 and 14-40. In parallel topology, each DCSB failure affects only its own tray’s -40 code

Understanding which configuration is installed on the machine under service is the essential first step in 14-40 diagnosis. It determines how many sub-boards are in the Tray 4 communication chain, which harnesses to inspect, and whether a 13-40 + 14-40 co-occurrence points to a single shared failure point or two independent failures.

FieldDetails
Jam Code14-40
KM Category HeadingMisfeed at Tray 4 Feed Section — the 14-xx category covers all fault types originating in Tray 4. The -40 suffix specifically means image write signal timeout (WTEN not issued within permitted window after paper arrival at registration sensor). This is a board-level synchronization failure, not a mechanical paper transport misfeed
DescriptionTray 4 image write signal timeout — paper from Tray 4 reached the registration sensor on time, but the image write start signal permission (WTEN) was not issued within the specified period. The paper is found clean and undamaged at the registration nip — it was held in the wait position and never driven into the imaging zone
Critical distinction from 14-01 / 14-02Paper DID reach the registration sensor — Tray 4 mechanical feed is confirmed functional. The fault is in the WTEN handshake chain, not in the Tray 4 paper delivery mechanism. Do not replace Tray 4 feed rollers, the Tray 4 feed clutch, or any Tray 4 transport component to resolve 14-40
Critical structural distinction from 11-40 / 12-40 / 13-40Tray 4 is always an optional unit — there is no built-in Tray 4 on any bizhub model. A dedicated LCT sub-board (DCSB / OACB) always exists in the Tray 4 communication chain. Two hardware configurations are possible: (A) dual-cassette single LCT with one shared DCSB serving T3 and T4, or (B) stacked dual LCT units each with an independent DCSB. The configuration determines the diagnostic path. In stacked dual-LCT daisy-chain configurations, the Tray 4 DCSB communicates through the Tray 3 DCSB before reaching the base machine engine board — adding a second sub-board as an independent failure point
Detection Logic — BASEB models with dual PF units (C250i / C300i / C360i / C3350i / C4050i):After Tray 4 paper arrival at the registration sensor (PS1 or PS9), the image write start signal permission (WTEN) was not received within the specified count from the print controller. Registration clutch (CL4) was not authorized to fire. Tray 4 requires dual stacked PF units; the Tray 4 DCSB communicates to BASEB via the Tray 3 DCSB or directly via a parallel harness (model and configuration-dependent)
Detection Logic — MFPB / FRB models with dual LCT (C258 / C368 / C458 / C658 / 368e / 658e):The image write start signal (WTEN) from the print controller to the engine board was not confirmed within the permitted timing window following Tray 4 paper detection at the registration sensor (PS1 / PS72). Tray 4 paper feeds from a second optional lower cassette unit; its DCSB / OACB reports paper position to the MFPB either through the Tray 3 DCSB (daisy-chain) or via an independent harness (parallel). Tray 4 paper also passes through the Tray 3 LCT transport section as a physical pass-through before entering the base machine paper path
Detection Logic — PFTDB models with extended LCT (758 / 808 / 958 / C659 / C759 / 654e / 754e):Paper fed from Tray 4 arrived at the vertical transport sensor, but the image write start signal was not issued before the WTEN timeout counter expired. On PFTDB platform models, Tray 4 may be served by the PFTDB managing an extended cassette stack, or by an additional DCSB in the optional unit stack communicating to the PFTDB. Confirm the Tray 4 configuration for the specific model before diagnosing
Key ComponentsPrint controller board (CPUB / controller PCB); primary engine control board (BASEB / MFPB / PRCB / PFTDB); Tray 4 LCT sub-board (DCSB-T4 / OACB-T4 — second independent sub-board in stacked-dual-LCT configuration, or shared DCSB in dual-cassette single LCT configuration); Tray 3 LCT sub-board (DCSB-T3 / OACB-T3 — in daisy-chain stacked configurations, Tray 4 DCSB communicates through Tray 3 DCSB to reach the primary engine board); Tray 4 DCSB-to-Tray3-DCSB inter-unit harness (daisy-chain only); Tray 3 DCSB-to-base-machine harness; Tray 4 DCSB-to-base-machine harness (parallel configuration only); registration clutch (CL4 / CL4A — MFPB/BASEB/PRCB platform; direct drive on PFTDB platform); Tray 4 paper feed clutch (CL7 on MFPB/BASEB platform; CL4 or model-specific on PFTDB platform — see component table); registration sensor (PS1 / PS9 / PS4 — see table); Tray 4 paper feed sensor (PS4 on MFPB/BASEB platform; PS8 on PFTDB platform — see table); Tray 4 vertical transport sensor (PS40 / model-specific — where fitted); HDD / SSD; firmware on CPUB, primary engine board, Tray 3 DCSB, and Tray 4 DCSB (up to four independent firmware elements to version-check)
SeverityHigh — Tray 4 disabled for print; may be intermittent before becoming consistent; paper found clean and undamaged at the registration nip; frequently co-occurs with 13-40 when the shared LCT harness or dual-cassette DCSB has failed; co-occurrence with 11-40 and 12-40 indicates base machine controller or firmware failure rather than LCT-specific fault
Related Jam Codes13-40 (Tray 3 image write signal timeout — shares LCT sub-board in dual-cassette configurations; shares DCSB-T3-to-base-machine harness in daisy-chain configurations), 11-40 / 12-40 (Tray 1 / Tray 2 image write signal timeout — when co-occurring with 14-40, confirms base machine controller or firmware fault), 10-40 (bypass tray image write signal timeout), 20-40 (vertical transport image write signal timeout), 14-01 (Tray 4 primary misfeed — paper never reached registration sensor), 14-02 (Tray 4 registration loop forming failure — mechanical timing fault)

All Affected Models, LCT Configurations, and Exact Component References

Jam Code 14-40 applies to bizhub models configured with a fourth paper source via optional lower cassette units. Because Tray 4 is always an optional unit, the specific LCT hardware configuration — dual-cassette single unit or stacked dual units — must be identified before consulting the component reference table. Sensor designations differ between MFPB platform models (where PS4 is the Tray 4 feed sensor and PS1 is the registration sensor) and PFTDB platform models (where PS4 is the registration sensor and PS8 is the Tray 4 feed sensor). This naming overlap makes the model platform identification mandatory before any sensor check is performed in Service Mode.

bizhub ModelsLCT ConfigT4 Feed SensorT4 VT SensorReg. SensorT4 Feed ClutchReg. ClutchT4 Sub-BoardT4–T3 Inter-Unit HarnessT3–Base HarnessCL7 / T4 Clutch CheckCL4 CheckPrimary Engine Board
C250i / C300i / C360i / 250i / 300i / 360i (dual PF units)Stacked dual LCT (PF-707 × 2) — daisy-chain DCSB topologyPS4—PS1CL7CL4DCSB-T4 (in lower PF unit)DCSB-T4 → DCSB-T3 harness (refer to SM)DCSB-T3 → BASEB harness (refer to SM)CC:20 MC:4, refer to SMCC:21 MC:2, BASEB CN15E-2, 3-CBASEB
C3350i / C4000i / C4050i (dual PF units)Stacked dual LCT — daisy-chain DCSB topologyPS4—PS9CL7CL4DCSB-T4 (in lower PF unit)DCSB-T4 → DCSB-T3 harness (refer to SM)DCSB-T3 → BASEB harness (refer to SM)CC:20 MC:4, refer to SMCC:21 MC:3, BASEB CN22EA-3, 12-CBASEB
C258 / C308 / C368 / C227 / C287 / C367 (dual PF units)Dual-cassette single LCT (PF-714 dual-drawer) or stacked dual LCT (PF-707 × 2)PS4—PS1CL7CL4DCSB-T4 or shared DCSB (see LCT config)Inter-unit harness (stacked only, refer to SM)DCSB-T3 or shared DCSB → MFPB (refer to SM)CC:20 MC:4, refer to SMCC:21 MC:2, FRB CN8-7, 5-LMFPB + FRB
368e / 308e (dual PF units)Dual-cassette single LCT or stacked dual LCTPS4—PS1CL7CL4DCSB-T4 or shared DCSB (see LCT config)Inter-unit harness (stacked only, refer to SM)DCSB / OACB → MFPB harness (refer to SM)CC:20 MC:4, refer to SMCC:21 MC:2, FRB CN8-7, 5-LMFPB + FRB
C458 / C558 / C658 / 458e / 558e / 658e (dual PF units)Dual-cassette single LCT (PF-740 dual) or stacked dual LCT (PF-740 × 2 or PF-707 × 2)PS4—PS1 (PS72 on 658e/558e)CL7CL4DCSB-T4 or shared DCSB (see LCT config)Inter-unit harness (stacked only, refer to SM)DCSB / OACB → MFPB harness (refer to SM)CC:20 MC:4, refer to SMCC:21 MC:2, FRB CN8-7, 4-KMFPB + FRB + EXCB
C450i / C550i / C650i / 458i / 558i / 658i (dual PF units)Dual-cassette single LCT or stacked dual LCT (refer to SM for model)PS4—PS1CL7CL4DCSB-T4 or shared DCSB (refer to SM)Refer to SMRefer to SMRefer to SMRefer to SMMFPB + EXCB + FRB + BASEB
C224e / C284e / C364e / C224 / C284 / C364 (dual PF units)Dual-cassette single LCT or stacked dual LCT (refer to SM)PS4—PS1CL7CL4DCSB-T4 or shared DCSB (refer to SM)Refer to SMRefer to SMRefer to SMRefer to SMPRCB / MFPB
C454 / C554 / 223 / 283 / 363 / 423 (dual PF units)Dual-cassette single LCT or stacked dual LCT (refer to SM)PS4—PS1CL7CL4DCSB-T4 or shared DCSB (refer to SM)Refer to SMRefer to SMRefer to SMRefer to SMPRCB
654e / 754e (extended LCT / dual-cassette LCT)Dual-cassette single LCT or extended PFTDB-managed cassette stackPS8 (T4 feed) / PS40 (T4 VT, where fitted)PS40PS4CL4 (PFTDB model-specific)— (direct drive)DCSB-T4 or PFTDB-managed (refer to SM)Refer to SMDCSB → PFTDB harness (refer to SM)Refer to SMRefer to SMPFTDB + MFPB
758 / 808 / 958 / PRO 958 (extended LCT stack)Dual-cassette single LCT or stacked dual LCT extending PFTDB stackPS8 (T4 feed) / PS40 (T4 VT, where fitted)PS40PS4CL4 (PFTDB model-specific)— (direct drive)DCSB-T4 or PFTDB-managed (refer to SM)Refer to SMDCSB → PFTDB harness (refer to SM)Refer to SMRefer to SMPFTDB + MFPB
C659 / C759 (extended LCT stack)Dual-cassette single LCT or stacked dual LCTPS8 / PS40 (refer to SM)PS40PS4CL4 (model-specific, refer to SM)— (refer to SM)DCSB-T4 or PFTDB-managed (refer to SM)Refer to SMRefer to SMRefer to SMRefer to SMPFTDB + MFPB

CC = Check Code, MC = Multi Code, SM = Service Manual, LCT = Lower Cassette Tray / optional paper feed unit, VT = Vertical Transport. CRITICAL: On MFPB/BASEB/PRCB platform models, PS4 = Tray 4 feed sensor and PS1 = registration sensor. On PFTDB platform models, PS4 = registration sensor and PS8 = Tray 4 feed sensor. Confirm the platform before performing any sensor check in Service Mode.

ℹ️ Identifying the LCT configuration before diagnosing 14-40 — mandatory first step: The diagnostic path for 14-40 diverges immediately based on which LCT hardware configuration is installed. Before Step 1, identify the configuration: Open the lower cassette area and count the physical LCT cabinet units. One cabinet with two cassette drawers (dual-cassette single LCT — Configuration A): One DCSB/OACB serves both Tray 3 and Tray 4. A failed DCSB produces 13-40 + 14-40 simultaneously. One harness connects the single unit to the base machine. Two separate cabinet units stacked vertically (stacked dual LCT — Configuration B): Each unit has an independent DCSB. Identify whether the wiring topology is daisy-chain (Tray 4 DCSB → Tray 3 DCSB → base machine) or parallel (each DCSB independently wired to base machine). In daisy-chain topology: Tray 4 DCSB or its inter-unit harness failure produces isolated 14-40; Tray 3 DCSB or its harness to the base machine failure produces both 13-40 and 14-40. In parallel topology: each DCSB failure affects only its own tray’s -40 code. Document the configuration and topology in the service log for future reference.

Understanding the WTEN Handshake for Tray 4 — Why the Timeout Occurs

The image write signal (WTEN — Write Enable) handshake for Tray 4 paper follows the same logical sequence as all lower trays, but involves the most complex hardware chain and the longest paper path of any standard tray on any bizhub configuration. The WTEN timeout window for Tray 4 is the longest of any standard internal tray source, calibrated to account for the full paper travel distance from the bottom of the optional lower cassette stack to the registration sensor at the top of the base machine paper path. Despite this generous timeout window, board-level communication failures and firmware mismatches produce 14-40 on every print cycle regardless of the timeout duration — because the fault is in communication latency, not in paper travel time.

On stacked dual-LCT Configuration B with daisy-chain topology, the WTEN handshake involves an additional communication link that is unique to Tray 4 and does not exist for any higher-numbered tray: the Tray 4 DCSB must communicate paper position data to the Tray 3 DCSB before the Tray 3 DCSB can report combined lower-unit status to the primary engine board. This creates a three-board communication chain (CPUB → primary engine board → Tray 3 DCSB → Tray 4 DCSB) where a failure at any link can produce 14-40.

The full Tray 4 feed sequence and WTEN handshake is:

  1. The primary engine board issues a Tray 4 feed command. In Configuration A (dual-cassette single LCT), this command travels to the shared DCSB which energizes the Tray 4 feed clutch (CL7 / CL4 / model-specific). In Configuration B daisy-chain, the command travels from the primary engine board to the Tray 3 DCSB, then from the Tray 3 DCSB to the Tray 4 DCSB, which then energizes the Tray 4 feed clutch locally
  2. The Tray 4 feed clutch engages, driving the Tray 4 pickup and separation rollers. Paper is fed from the Tray 4 cassette into the Tray 4 unit’s lower vertical transport section and begins travelling upward
  3. The Tray 4 paper feed sensor (PS4 on MFPB/BASEB platform; PS8 on PFTDB platform) triggers, confirming exit from the Tray 4 cassette assembly. The DCSB-T4 reads this sensor and reports paper presence to the next board in the communication chain
  4. The paper enters the Tray 3 LCT unit’s transport section from below — a physical pass-through section. The Tray 4 paper does not feed from the Tray 3 cassette; it uses the Tray 3 unit’s roller transport as a mechanical highway to travel upward through the Tray 3 unit and into the base machine paper path. Where intermediate VT sensors are fitted in the Tray 3 unit’s pass-through path (PS39 / PS40 / model-specific), these sensors confirm the Tray 4 paper’s passage through this section. The DCSB-T3 monitors these sensors and reports to the primary engine board
  5. The paper exits the top of the Tray 3 LCT unit into the base machine lower transport section and continues upward to the registration area
  6. The paper leading edge triggers the registration sensor (PS1, PS9, or PS4 depending on platform). The primary engine board logs a confirmed Tray 4 paper arrival event and starts the WTEN timeout countdown
  7. The primary engine board signals the print controller (CPUB) that Tray 4 paper is present at the registration roller and ready to enter the imaging zone. The controller confirms all imaging subsystems — polygon mirror motor, laser diode, photoconductor drum drive, image write unit — are at synchronized ready state, and that the current page’s image data has been fully transferred from the HDD/SSD to the print buffer
  8. When all subsystems report ready, the controller issues the WTEN signal to the primary engine board. The engine board commands the registration clutch (CL4, or direct drive equivalent on PFTDB platform) to release the paper into the imaging zone with a precisely timed leading-edge entry synchronized to the laser write start position
  9. 14-40 fires when the WTEN signal is not received by the primary engine board within the programmed timeout period for a Tray 4 feed. The paper has been held stationary at the registration nip throughout the countdown. The timeout expires, the transport sequence is abandoned, and 14-40 is logged. The jammed paper is found clean and undamaged at the registration nip area, held in the wait position, never driven into the imaging zone

Six root cause categories produce 14-40 — the most of any tray-sourced -40 code, reflecting the additional communication chain components unique to Tray 4:

  • Category 1 — Tray 4 LCT sub-board (DCSB-T4 / OACB-T4) internal failure — dominant cause of Tray-4-isolated 14-40 in stacked Configuration B: The Tray 4 DCSB has failed internally. It cannot report Tray 4 paper position to the next board in the chain, cannot receive feed commands, or has lost its internal timing reference. Because DCSB-T4 is unique to the Tray 4 communication path, its failure produces isolated 14-40 while Tray 3, Tray 1, and Tray 2 all continue to print normally. This is the highest-probability single-component hardware failure for Tray-4-isolated 14-40 in stacked configurations — diagnose the Tray 4 DCSB before any other board
  • Category 2 — Shared DCSB failure (Configuration A only) — produces 13-40 + 14-40 simultaneously: In dual-cassette single LCT configurations, the single DCSB that serves both Tray 3 and Tray 4 has failed. Because it is the only sub-board for both trays, its failure blocks WTEN handshake initiation for both Tray 3 and Tray 4 simultaneously. The diagnostic signature is 13-40 + 14-40 co-occurring with Trays 1 and 2 printing normally. Only one DCSB exists to replace in this configuration
  • Category 3 — LCT inter-unit harness failure or DCSB-T3 failure in daisy-chain topology — produces 13-40 + 14-40 simultaneously: In stacked dual-LCT daisy-chain Configuration B, the Tray 4 DCSB communicates through the Tray 3 DCSB to reach the primary engine board. A failure in the harness from DCSB-T3 to the base machine engine board, or an internal failure of the DCSB-T3 itself, breaks the communication chain for both Tray 4 (which must route through DCSB-T3) and Tray 3 simultaneously. This produces 13-40 + 14-40 co-occurrence, identical in pattern to Category 2, but involving two separate units. The distinction: in Configuration A there is one cabinet with one DCSB; in Configuration B daisy-chain there are two cabinets each with their own DCSB
  • Category 4 — Base machine controller–engine board communication failure: The CPUB-to-primary-engine-board communication path has failed or degraded. This category produces 14-40 alongside -40 codes from all other tray sources (11-40, 12-40, 13-40) because the shared WTEN handshake is broken at the base machine level. The diagnostic signature is simultaneous -40 codes from every paper source
  • Category 5 — HDD / SSD image data transfer latency: A failing storage device cannot deliver page data to the print buffer within the WTEN timeout window on complex print jobs. The Tray 4 WTEN timeout window is the longest of any standard tray. This means a degrading HDD/SSD may first produce 14-40 on complex jobs before it produces 13-40 on the same jobs — the Tray 4 timeout provides more time for storage latency to accumulate before the fault threshold is reached. It is possible to encounter 14-40 on complex jobs from Tray 4 while Tray 3 (shorter timeout) still completes the same jobs successfully. This is the only -40 code where storage latency may produce a tray-4-isolated fault pattern on complex jobs even when the base machine controller path is fully functional
  • Category 6 — Firmware mismatch or corruption: Mismatched firmware between any boards in the Tray 4 communication chain produces WTEN handshake failures. For 14-40, up to four independent firmware elements may be involved: the CPUB, the primary engine board, the Tray 3 DCSB, and the Tray 4 DCSB. A firmware update session that updated the CPUB and primary engine board but did not reach either or both DCBs — a common outcome of a partially completed update on machines with optional units that were powered off or disconnected during the update — produces 14-40 (and possibly 13-40) in isolation from lower trays while all base-machine sources print normally

Step 1 — Identify the LCT Configuration and Clear the Paper

Before any other diagnostic action, identify the LCT hardware configuration installed on the machine. This determines the communication chain topology, the number of sub-boards to inspect, and how to interpret the 13-40 + 14-40 co-occurrence pattern. Then clear the jammed paper and confirm its stop position.

  1. Identify the LCT configuration: Count the physical LCT cabinet units below the base machine. One cabinet with two cassette drawers = Configuration A (dual-cassette single LCT, single shared DCSB). Two separate cabinet units stacked vertically = Configuration B (stacked dual LCT, two independent DCBs). If uncertain, consult the installation record or open the LCT access panel and visually confirm whether one controller board or two are present in the optional unit stack. Document the confirmed configuration before proceeding
  2. Open the right-side cover, lower front door, Tray 4 LCT access panel, or any access indicated by the operator panel jam indicator. If the paper spans the Tray 4 unit–to–Tray 3 unit junction or the Tray 3 unit–to–base machine junction, clear from both ends simultaneously to avoid tearing fragments into the transport at the junction points. In stacked dual-LCT installations, the paper may span two unit junctions — confirm paper is fully cleared from all three sections before closing any panel
  3. Observe where the paper stopped and assess its physical condition:
    • Paper found clean, flat, and undamaged at the registration roller nip area — leading edge at or just past the registration nip, trailing edge in the base machine lower transport or still in the upper section of the Tray 3 unit’s pass-through path: This is the definitive 14-40 stop position. The paper completed its entire four-section transport path correctly and was held at the nip awaiting authorization. Clean condition confirms registration clutch never fired. Proceed to Step 2
    • Paper found at the Tray 3–to–base machine junction or in the base machine lower transport, well below the registration area: This stop position belongs to 14-01 or 14-02, not 14-40. If the panel shows 14-40 but paper is stopped in the lower transport sections, a sensor may be falsely reporting paper arrival at the registration sensor. Confirm the registration sensor state in Service Mode before concluding the code is correct
    • Paper found buckled or crumpled at the registration area: More consistent with 14-02 (loop forming failure). Verify the jam code. If 14-40 is confirmed but paper is mechanically damaged, resolve any concurrent 14-02 first
    • Paper found in the Tray 4 unit’s own transport section or at the Tray 4–to–Tray 3 pass-through junction: This stop position is 14-01 territory. A paper stop this deep in the Tray 4 unit confirms a Tray 4 mechanical transport failure — the paper never reached the registration sensor and 14-40 would not correctly apply. Recheck the jam code and inspect the Tray 4 unit transport rollers and pass-through junction rollers at the Tray 4–to–Tray 3 interface
    • No paper found: Partial ejection or a false sensor trigger. Check the registration sensor state in Service Mode. A registration sensor stuck ON delivers a permanent false paper-present signal on every Tray 4 feed cycle, corrupting the WTEN handshake initiation
  4. After clearing the paper, inspect the Tray 4 unit transport section, the Tray 4–to–Tray 3 unit junction, the Tray 3 pass-through transport rollers, and the Tray 3–to–base machine junction for paper fragments, paper dust on sensor windows, and debris at the roller nip points. Paper dust accumulation on the intermediate VT sensors in the Tray 3 pass-through section is a common source of intermittent false sensor signals on high-volume Tray 4 installations

Step 2 — Check for Associated Error Codes, Review Service History, and Map the Fault Scope

The error log and service history provide the single most important diagnostic information for 14-40: the pattern of co-occurring jam codes that identifies exactly where in the communication chain the fault is located. No other diagnostic action is as efficient at narrowing the 14-40 root cause as an accurate reading of the error history in the context of the confirmed LCT configuration.

  1. Access the Error History log in Service Mode. Review the last 20–50 logged events. Map the co-occurrence pattern against the confirmed LCT configuration:
    • 14-40 in isolation — Trays 1, 2, and 3 printing normally:
      Configuration A (single dual-cassette LCT, shared DCSB): The shared DCSB should be producing both 13-40 and 14-40 if it has failed. Isolated 14-40 in Configuration A suggests the DCSB is partially functional — reporting Tray 3 paper correctly but failing on Tray 4 paper position. Investigate the DCSB and the Tray 4 sensor circuit on the DCSB before replacing the entire board
      Configuration B stacked daisy-chain: Isolated 14-40 confirms the Tray 4 DCSB or its inter-unit harness to the Tray 3 DCSB. Proceed to Step 3 (Tray 4 DCSB harness) immediately
      Configuration B stacked parallel: Isolated 14-40 confirms the Tray 4 DCSB or its independent harness to the base machine. Proceed to Step 3
    • 14-40 + 13-40 — Trays 1 and 2 printing normally:
      Configuration A: Confirmed shared DCSB failure or shared LCT-to-base-machine harness failure. One DCSB to check, one harness to inspect
      Configuration B daisy-chain: Either the Tray 3 DCSB has failed (cutting off both Tray 3 and Tray 4 communication to the base machine) or the harness from the Tray 3 DCSB to the base machine engine board has failed. The Tray 4 DCSB itself may be functional — its communication cannot reach the base machine because the Tray 3 DCSB or harness upstream of it has failed. Inspect the Tray 3 DCSB–to–base machine harness before the Tray 3 DCSB, and before the Tray 4 DCSB
      Configuration B parallel: Both the Tray 3 and Tray 4 DCBs have failed independently, or the base machine engine board’s optional-unit interface has failed. Simultaneous failure of two independent DCBs is uncommon — suspect the base machine interface connector first
    • 14-40 + 13-40 + 12-40 + 11-40 (all sources showing -40 codes): Base machine CPUB failure or base machine controller–engine board communication harness failure. LCT sub-boards are not involved. Proceed to Step 4 (base machine controller–engine communication)
    • 14-40 with HDD or storage error codes: Proceed to Step 6 (HDD/SSD inspection)
    • 14-40 with polygon motor or imaging section error codes: Proceed to Step 7 (imaging section verification)
    • 14-40 immediately after a firmware update: Proceed to Step 5 (firmware verification — all boards including both DCBs)
  2. Check the service history for LCT-specific interventions: Tray 4 LCT unit relocation, DCSB replacement, inter-unit harness replacement, LCT firmware update, or base machine relocation that required LCT disconnection. A 14-40 that appeared within 1–5 days of any LCT-related work is overwhelmingly likely to be related to that work — a disturbed inter-unit harness connector or improperly reseated DCSB connector is the primary suspect
  3. Determine whether 14-40 is consistent or intermittent:
    • Consistent 14-40 on every Tray 4 print — hard failure in the DCSB-T4, DCSB-T3 (daisy-chain), shared harness (Configuration A), or base machine controller (if multi-source)
    • Intermittent 14-40 — particularly correlated with ambient temperature changes, time-of-day, or machine vibration — suggests a marginal connector contact. The Tray 4 inter-unit harness connector at the Tray 4–to–Tray 3 junction is the most mechanically stressed single connector in any optional LCT stack and is the most common source of vibration-induced intermittent 14-40
    • Intermittent 14-40 correlated with complex or graphics-heavy print jobs — investigate HDD/SSD latency (Step 6) before hardware inspection

Step 3 — Inspect and Reseat All LCT Sub-Board Harnesses and Connectors

For any 14-40 pattern that implicates LCT-specific components (isolated 14-40, or 14-40 + 13-40 with Trays 1 and 2 normal), the LCT harnesses and DCSB connectors must be inspected and reseated before any board replacement. The inter-unit harness between the Tray 4 unit and the Tray 3 unit is the single most vulnerable connector in any dual-LCT installation — it is disconnected at every LCT unit relocation and accumulates mechanical wear faster than any internal board connector.

  1. Power down the machine completely and disconnect the main power cord. Wait a minimum of 30 seconds before accessing any board or disconnecting any harness
  2. For Configuration A (dual-cassette single LCT — one DCSB):
    • Locate the single harness connecting the dual-cassette LCT unit to the base machine. Disconnect and inspect both ends: the DCSB connector inside the LCT unit and the connector at the base machine engine board interface
    • Inspect all pins in both the plug and socket: bending, corrosion, backed-out pins, or bridging. Inspect harness jacket at entry points for chafing. Confirm connector latch engagement
    • Access the DCSB inside the LCT unit and reseat all connectors: Tray 3 feed sensor harness, Tray 4 feed sensor harness, Tray 3 clutch drive harness, Tray 4 clutch drive harness, and any intermediate VT sensor harnesses
    • Reseat the main LCT-to-base-machine harness at both ends. Reconnect power and test
  3. For Configuration B stacked dual LCT — daisy-chain topology:
    • Identify and locate three harness connections in the chain: (1) the inter-unit harness from the Tray 4 DCSB to the Tray 3 DCSB at the junction between the two LCT cabinet units; (2) the harness from the Tray 3 DCSB to the base machine engine board interface; (3) the power supply harness to both DCBs
    • Inspect and reseat the inter-unit harness between Tray 4 DCSB and Tray 3 DCSB first — this is the harness disconnected most often during servicing and the most vulnerable to wear. Inspect all pins on both ends. A bent or corroded pin at this connector produces isolated 14-40 while Tray 3 prints normally
    • Inspect and reseat the Tray 3 DCSB–to–base machine harness second. A failed connector at this point produces both 13-40 and 14-40 simultaneously
    • Access the Tray 4 DCSB and the Tray 3 DCSB individually. Reseat all connectors on both boards: feed sensor harnesses, VT sensor harnesses, clutch drive harnesses, and inter-board communication connectors
    • Inspect harness routing between all three units for pinch points where the harness passes through gaps between cabinets during stacking — a pinched harness at a stacking interface creates an internal conductor break that is invisible externally
  4. For Configuration B stacked dual LCT — parallel topology:
    • Each DCSB has an independent harness to the base machine engine board. Locate and inspect both independent harnesses and reseat both at the DCSB end and the base machine end
    • Reseat all connectors on both the Tray 4 DCSB and the Tray 3 DCSB independently
  5. After all reseating is complete, reconnect power, power on, and run a 30-page Tray 4 test job. If 14-40 clears after harness reseating, the cause was mechanical contact degradation in the Tray 4 communication path. Monitor over 500 Tray 4 prints before declaring the repair complete. On high-vibration sites, consider applying additional harness strain relief at the inter-unit connector point and proactively replacing the inter-unit harness on machines above 500k copies, regardless of whether reseating resolved the fault

Step 4 — Test the Full Controller–Engine Communication Path in Service Mode

If 14-40 co-occurs with -40 codes from Tray 1 or Tray 2 (base machine sources), or if LCT harness reseating did not resolve a Tray-4-specific 14-40, Service Mode communication diagnostics identify base machine communication path faults before any board replacement.

  1. Enter Service Mode (Tech Rep Mode) on the machine
  2. Navigate to the I/O check or board communication diagnostic section:
    • BASEB models: Access the BASEB diagnostic menu. Verify CPUB–BASEB communication status. Check the optional device connection status — BASEB i-series models typically report both the Tray 3 LCT and Tray 4 LCT (or the dual-cassette LCT) as separate or combined entries in the optional device list. “Not connected” or “communication error” for the Tray 4 entry confirms a Tray-4-specific sub-board or harness failure, not a base machine fault
    • MFPB + FRB models: Verify CPUB–MFPB communication status. Check the optional device status section for the Tray 3 and Tray 4 LCT entries. A Tray 4 LCT shown as “not detected” while Tray 3 LCT shows as detected and communicating confirms a Tray-4-DCSB or Tray-4-inter-unit-harness failure in Configuration B daisy-chain topology. Both Tray 3 and Tray 4 showing “not detected” with Tray 1 and Tray 2 normal confirms the Tray-3-DCSB-to-base-machine harness failure (in daisy-chain) or a failed shared DCSB (Configuration A)
    • PFTDB models: Verify the full CPUB → MFPB → PFTDB chain and check the PFTDB optional device status for all connected lower-cassette units. PFTDB models display per-link status for each optional unit in the cassette stack
  3. Command the registration clutch (CL4 or direct drive equivalent) using the model-specific check code. Confirmed engagement means the engine board CL4 output circuit is functional — the fault is in the WTEN authorization path upstream, not in the clutch drive circuit
  4. Verify the Tray 4 feed sensor (PS4 on MFPB/BASEB platform; PS8 on PFTDB platform) by inserting paper into the sensor window and confirming state toggle in Service Mode. On daisy-chain configurations, the Tray 4 sensor is read by DCSB-T4 and reported through DCSB-T3 — if the sensor does not appear to respond, the DCSB-T4 may not be communicating rather than the sensor itself being failed. Cross-reference with the optional device status to distinguish sub-board communication failure from sensor failure
  5. Command the Tray 4 feed clutch (CL7 / CL4 model-specific) using the check code. In daisy-chain Configuration B, this command must traverse the full chain to DCSB-T4 before CL7 engages. If the clutch does not engage on command despite confirmed harness seating, the DCSB-T4 is not receiving commands — it has failed or is not communicating with the board upstream of it in the chain
  6. In daisy-chain Configuration B, also command the Tray 3 pass-through transport motor (or confirm motor operation through Service Mode) to verify the Tray 3 unit’s pass-through transport rollers are operational. A failed Tray 3 pass-through transport motor does not produce 14-40 (it would produce 14-01 or 14-02), but confirming it is running rules out a compounding mechanical fault in the pass-through section

Step 5 — Verify Firmware on All Boards — Including Both LCT Sub-Board Firmware Versions

Firmware verification for 14-40 is more complex than for any other tray-sourced -40 code because up to four independent firmware elements may be involved: the CPUB, the primary engine board, the Tray 3 DCSB, and the Tray 4 DCSB. On machines where 14-40 appeared after a firmware update, this step must precede every hardware intervention — it resolves post-update 14-40 completely without requiring any board replacement.

  1. In Service Mode, navigate to the firmware version display. Record the firmware version for every board carrying independent firmware:
    • Main controller (CPUB / print controller)
    • Primary engine board (MFPB / BASEB / PRCB / PFTDB)
    • Tray 3 DCSB / OACB firmware version (in the optional device firmware section of Service Mode — not in the main board listing)
    • Tray 4 DCSB / OACB firmware version (separate entry from Tray 3 DCSB, in the optional device firmware section)
    • In Configuration A (shared DCSB): only one DCSB firmware version to check — but confirm it reflects the version that is compatible with the current primary engine board firmware
  2. Cross-reference all four versions against the official firmware compatibility matrix for this model and LCT unit combination. The critical mismatches that produce 14-40 in isolation are:
    • DCSB-T4 firmware at an older version than DCSB-T3 and the primary engine board — a firmware update that reached DCSB-T3 but not DCSB-T4 leaves the Tray 4 DCSB using a legacy handshake protocol that the updated DCSB-T3 or engine board no longer accepts
    • DCSB-T4 firmware at a newer version than DCSB-T3 — if the Tray 4 unit was serviced or its DCSB was replaced with a pre-flashed board at a newer version than the Tray 3 DCSB, the forward-incompatible handshake produces isolated 14-40
    • Both DCSB-T3 and DCSB-T4 at older versions than the primary engine board — a base machine firmware update that did not include the optional unit firmware update session produces 13-40 + 14-40 co-occurrence
  3. If any firmware mismatch is confirmed across any boards in the chain, perform a complete firmware reinstall for all boards simultaneously from the current official firmware bundle. The bundle must include: CPUB firmware, primary engine board firmware, Tray 3 DCSB firmware, and Tray 4 DCSB firmware. Update all four in the same session. Do not defer any board’s update to a later session — a partial update repeats the mismatch in the opposite direction
  4. After firmware reinstall, perform a complete cold power cycle: power off, disconnect main power cord, wait 60 seconds, reconnect, power on. Allow the machine to complete its full initialization sequence — including optional unit detection and both DCSB communication establishments — before sending any test print. On machines with two stacked LCT units, the initialization sequence is longer than on single-LCT machines; do not send a test print until the panel shows Ready status with all optional units detected
  5. After reinstall, verify all four firmware versions in Service Mode before running a test job, and confirm both DCSB units appear as detected and communicating in the optional device status display

Step 6 — Inspect and Test the HDD / SSD (Image Data Delivery Path)

When 14-40 correlates with complex or graphics-heavy print jobs and Tray 3 (shorter timeout) completes the same jobs successfully, the Tray 4 WTEN timeout window — the longest of any standard tray — is providing time for storage latency to accumulate past the threshold before Tray 3’s shorter window is also exceeded. A degrading storage device may first produce 14-40 before 13-40 appears on the same job types, making isolated complex-job 14-40 the earliest storage degradation signal in machines with Tray 4 installed.

  1. In Service Mode, navigate to the HDD/SSD diagnostics section. Run the storage self-test or diagnostic check and note all reported bad sectors, read errors, degraded throughput, or SMART indicators. Document the results and compare against any prior PM diagnostic logs if available
  2. Review the error history for storage error codes preceding or accompanying the first occurrence of 14-40. Storage error codes appearing in the hours or days before 14-40 became consistent confirm storage degradation as the timeline root cause
  3. Reproduce the fault with a controlled test: send a complex graphics-heavy multi-page print job from Tray 4, then send the same job from Tray 3, then from Tray 1:
    • 14-40 from Tray 4 only on the complex job, Tray 3 and Tray 1 complete it — Tray 4 WTEN timeout is being exceeded by storage latency that has not yet reached the Tray 3 or Tray 1 threshold. Storage device degradation is confirmed
    • 14-40 from Tray 4 and 13-40 from Tray 3 on the complex job, Tray 1 completes it — storage latency has progressed to exceed both Tray 4 and Tray 3 windows but not yet the shorter Tray 1 window. Storage replacement is urgent
    • 14-40 from Tray 4 on both complex and simple jobs — storage latency is not the mechanism; the timeout is occurring regardless of image data size. Board communication or sub-board failure is the cause
  4. Reseat the HDD/SSD data cable at both ends. Vibration from the large optional cassette unit stack’s transport motors can contribute to data cable contact degradation on machines with extended LCT configurations, as the mechanical vibration footprint is larger than on single-tray base configurations
  5. If HDD/SSD diagnostic errors, bad sectors, or degraded throughput are confirmed, replace the storage device. Follow the model-specific storage initialization procedure in Service Mode. Back up all machine-specific settings and counter data before removal where supported

Step 7 — Verify Imaging Section Ready State (Polygon Motor and Laser Unit)

When 14-40 is accompanied by imaging section error codes or abnormal polygon motor behavior, the imaging section failing to reach ready state is blocking WTEN from being issued for all paper sources. In this scenario, 14-40 will invariably be accompanied by 11-40, 12-40, and 13-40 simultaneously — polygon motor and laser unit failures block WTEN for all tray feeds equally. Isolated 14-40 is therefore very unlikely to be caused by an imaging section component failure; this step applies primarily when 14-40 co-occurs with -40 codes from all other sources alongside imaging error codes.

  1. During machine warm-up, listen to the imaging section. A clean, steady polygon motor tone confirms normal acceleration to rated speed. Intermittent tone, bearing noise, or failure to stabilize within the normal warm-up period indicates polygon motor degradation
  2. In Service Mode, command the polygon motor to run and verify it achieves and holds ready status within the specified time. A polygon motor that does not reach ready status prevents WTEN from being issued for any paper source. If 14-40 is truly isolated to Tray 4 and the polygon motor achieves ready status, the polygon motor is not the cause — proceed to the LCT sub-board and harness investigation
  3. On color models, verify all four laser channels (YMCK) reach ready state. A single failed color channel prevents WTEN for all tray sources
  4. If polygon motor or laser unit failure is confirmed, replace the LSU assembly per the model-specific service manual. Run color registration calibration immediately after LSU replacement on color models before any print quality or jam code verification test

Step 8 — Replace the LCT Sub-Board(s) or Control Board (Systematic Sequence)

When all preceding steps are complete and 14-40 persists, board replacement follows a sequence determined by the confirmed LCT configuration and the co-occurrence pattern identified in Step 2. The sequence is different for each configuration.

  • Configuration A (dual-cassette single LCT) — Replace the shared DCSB / OACB first: There is only one sub-board in this configuration. When harness reseating and firmware reinstall have not resolved 13-40 + 14-40 (both trays affected) or isolated 14-40 (Tray 3 circuit on DCSB partially functional), replace the shared DCSB. After replacement, confirm the new DCSB firmware version matches the primary engine board compatibility requirement — new DCBs may ship with an older firmware version requiring update before use. Complete a cold power cycle after replacement. Do not replace the base machine CPUB or MFPB until the shared DCSB is confirmed functional or replaced
  • Configuration B daisy-chain — isolated 14-40 — Replace DCSB-T4 first: In stacked dual-LCT daisy-chain configurations where 14-40 is isolated to Tray 4 and Tray 3 prints normally, the Tray 4 DCSB is the highest-probability failure. Replace DCSB-T4. Confirm new board firmware version. Cold power cycle. Verify Tray 4 appears as detected in the optional device status display before running a test print. Do not replace DCSB-T3 or any base machine board for isolated 14-40 until DCSB-T4 replacement is confirmed unsuccessful
  • Configuration B daisy-chain — 13-40 + 14-40 — Replace DCSB-T3 first: When both Tray 3 and Tray 4 are affected and the Tray 3–to–base-machine harness has been confirmed good, the Tray 3 DCSB is the highest-probability board failure — because it is the shared upstream board that serves both Tray 3 directly and Tray 4 as a pass-through in the communication chain. Replace DCSB-T3. After replacement, DCSB-T4 (which was communicating through the now-replaced DCSB-T3) should immediately show as detected. If 14-40 persists after DCSB-T3 replacement and Tray 3 is now printing normally, then DCSB-T4 has also failed independently — replace DCSB-T4 as a secondary action
  • Configuration B parallel — isolated 14-40 — Replace DCSB-T4 (independent harness configuration): Same as daisy-chain isolated 14-40 — DCSB-T4 is the direct and only sub-board responsible for the Tray 4 feed in this topology. Replace DCSB-T4. If 14-40 persists, inspect the independent Tray 4 DCSB-to-base machine harness for internal conductor damage before replacing any base machine boards
  • Replace CPUB next — for multi-source -40 codes (11-40 + 12-40 + 13-40 + 14-40) on MFPB platform models: bizhub C258/C308/C368, C458/C558/C658, 458e/558e/658e, 368e/308e, C450i/C550i/C650i. Replace CPUB first on MFPB platform models when all paper sources show -40 codes and all LCT components have been confirmed functional or replaced. Complete all CPUB initialization procedures in Service Mode after replacement before any test print
  • Replace MFPB after CPUB — MFPB platform models: If CPUB replacement does not resolve the multi-source -40 condition, replace the MFPB. MFPB failure in the WTEN path is less common than CPUB failure but is the correct next step when CPUB replacement is unsuccessful
  • Replace BASEB — C250i/C300i/C360i, 250i/300i/360i, C3350i, C4000i, C4050i: When all LCT components, firmware, HDD, and imaging section have been excluded and the fault persists across all sources, replace BASEB. Complete all new-board initialization procedures before testing
  • Replace PRCB, then MFPB — C224/C284/C364, C224e/C284e/C364e, C454/C554, 223/283/363/423: Replace PRCB first; replace MFPB only if PRCB replacement does not resolve the multi-source -40 condition
  • Replace PFTDB, then MFPB — 654e/754e, 758/808/958/PRO 958, C659/C759: Replace PFTDB first; replace MFPB only if PFTDB does not resolve the fault. On PFTDB models with an extended cassette stack managed by PFTDB, a PFTDB failure can selectively affect lower trays while leaving upper trays functional — confirm the PFTDB wiring diagram for the model before concluding whether isolated 14-40 points to PFTDB or to a DCSB in the optional stack

Quick Reference — Troubleshooting by Symptom

SymptomMost Likely CauseFirst Action
14-40 on every Tray 4 print; Trays 1, 2, and 3 print normally; Configuration B stacked daisy-chainTray 4 DCSB (DCSB-T4) internal failure or inter-unit harness from DCSB-T4 to DCSB-T3Inspect and reseat the DCSB-T4–to–DCSB-T3 inter-unit harness at both ends; confirm Tray 4 LCT appears as detected in optional device status; replace DCSB-T4 if harness is confirmed good
14-40 on every Tray 4 print; Trays 1, 2, and 3 print normally; Configuration A dual-cassette single LCTShared DCSB partially failing on Tray 4 sensor circuit, or Tray 4 clutch harness on the shared DCSBReseat all connectors on the shared DCSB — particularly the Tray 4 feed sensor harness and Tray 4 clutch drive harness; replace shared DCSB if reseating does not resolve after 50 Tray 4 test prints
14-40 + 13-40; Trays 1 and 2 print normally; Configuration A dual-cassette single LCTShared DCSB failure (single board serves both trays) or shared LCT-to-base-machine harness failureInspect and reseat the LCT-to-base-machine harness at both ends; confirm LCT appears as detected in optional device status; replace shared DCSB if harness is confirmed good
14-40 + 13-40; Trays 1 and 2 print normally; Configuration B stacked dual LCT daisy-chainTray 3 DCSB failure (upstream board cutting off both T3 and T4 communication) or DCSB-T3–to–base-machine harness failureInspect and reseat the DCSB-T3–to–base-machine harness first; if harness is good, replace DCSB-T3; if 14-40 persists after Tray 3 is restored, also replace DCSB-T4
14-40 + 13-40 + 12-40 + 11-40 (all sources showing -40 codes)Base machine CPUB failure or CPUB–engine board communication harness failure — not LCT-specificReseat CPUB–engine board communication connectors; perform firmware reinstall across all boards; replace CPUB first on MFPB platform models, BASEB on i-series
14-40 only on complex or graphics-heavy print jobs from Tray 4; Tray 3 completes the same job correctlyHDD/SSD degraded read performance — Tray 4’s longer WTEN window accumulates storage latency to threshold before Tray 3’s shorter window is exceededRun HDD/SSD diagnostic in Service Mode; check for storage error codes in error history; reseat HDD/SSD data cable; replace storage device if errors or degraded throughput confirmed
14-40 appeared immediately after a firmware update sessionFirmware mismatch between CPUB, primary engine board, DCSB-T3, and/or DCSB-T4; up to four boards to version-checkCheck all four firmware versions in Service Mode; confirm DCSB-T3 and DCSB-T4 both appear in optional device firmware list; perform full firmware reinstall including both LCT sub-board firmwares in the same session; cold power cycle
14-40 appeared after Tray 4 LCT unit was moved, reinstalled, or the machine was relocatedDCSB-T4–to–DCSB-T3 inter-unit harness connector disturbed during relocation — bent pins, partial disconnection, or latch failure at the inter-unit connectorInspect and reseat the inter-unit harness at both ends; visually inspect all pins for bending or handling damage; replace inter-unit harness if continuity test shows degraded contact
14-40 intermittent — fires 1 in 50–150 Tray 4 pages with no consistent job-type correlationMarginal contact at the DCSB-T4–to–DCSB-T3 inter-unit connector, working loose under machine vibration from the extended LCT transport stackReseat inter-unit harness at both ends and all DCSB-T4 connectors; inspect connector latch integrity; if reseating does not produce stable results over 300 Tray 4 prints, replace the inter-unit harness before replacing any boards
14-40 accompanied by polygon motor noise or imaging section error codesPolygon mirror motor or laser unit failing — blocks WTEN for all paper sources; expect concurrent 11-40, 12-40, 13-40 alongside 14-40Check polygon motor ready status in Service Mode; listen for abnormal tone during warm-up; replace LSU assembly if polygon motor fails ready status; run color registration calibration after LSU replacement on color models
Tray 4 feed sensor (PS4 on MFPB platform / PS8 on PFTDB platform) shows constant ON in Service Mode when Tray 4 transport path is clearTray 4 feed sensor stuck ON, or DCSB-T4 not correctly reporting sensor state to the upstream board (mistaken as constant paper presence at Tray 4 sensor location)Reseat Tray 4 feed sensor connector on DCSB-T4; clean sensor window; confirm DCSB-T4 appears as detected and communicating in optional device status; replace Tray 4 feed sensor if stuck-ON persists with confirmed connector seating and DCSB communication
14-40 persists after DCSB-T4, DCSB-T3 (or shared DCSB), and base machine CPUB replacementPhysical harness failure in the base machine CPUB–to–engine board communication path — internal base machine wiring open or intermittentTrace and test the complete serial communication harness from CPUB to primary engine board with a continuity meter; check for pinched harness at door hinge or routing clip stress points; replace harness if open or intermittent circuit confirmed
14-40 after any board replacement (new board installed, fault persists)New board not initialized correctly in Service Mode; firmware mismatch — new board version differs from compatibility requirement; or secondary board in the chain is also defectiveVerify all new-board initialization procedures completed per service manual; confirm all firmware versions match across all four boards; replace next board in the systematic sequence for the model and configuration

Understanding the 14-xx Tray 4 Jam Code Family

Jam Code 14-40 belongs to the Tray 4 jam code family, which Konica Minolta service documentation categorizes collectively under Misfeed at Tray 4 Feed Section. All 14-xx codes originate in the Tray 4 paper source, but the suffix digit defines the specific failure type with precision:

  • 14-01 — Tray 4 primary misfeed — paper never reached the registration sensor after the Tray 4 feed sequence was initiated. Total mechanical feed failure. Investigate Tray 4 feed roller, separation roller, Tray 4 feed clutch (CL7 / CL4 model-specific), and the Tray 4 unit’s own vertical transport section including the transport rollers at the Tray 4–to–Tray 3 junction. Paper stops in the Tray 4 cassette assembly, the Tray 4 unit’s transport section, or at the junction into the Tray 3 pass-through section
  • 14-02 — Tray 4 registration loop forming failure — paper reached the registration sensor area but arrived after the registration timing window had commenced. Marginal mechanical timing failure in the extended paper path, most commonly caused by worn transport rollers in the Tray 4 unit, worn pass-through transport rollers in the Tray 3 unit, or worn transport components at the LCT unit junctions. Paper stops at the registration area with a buckled or crumpled leading edge. Note that the Tray 3 unit’s pass-through transport rollers are subject to double wear — once from Tray 3 paper feeds and again from Tray 4 pass-through feeds — and may require inspection and replacement at shorter intervals than Tray 3 rollers on machines with heavy Tray 4 use
  • 14-40 — Tray 4 image write signal timeout — paper arrived correctly at the registration sensor, but the WTEN signal was not issued within the timeout window. Board-level synchronization failure, with up to four hardware elements in the Tray 4 communication chain: CPUB, primary engine board, DCSB-T3, and DCSB-T4. When isolated to Tray 4, investigate the DCSB-T4 and inter-unit harness first. When co-occurring with 13-40, investigate the DCSB-T3–to–base-machine harness, shared DCSB (Configuration A), or DCSB-T3 (daisy-chain Configuration B). When co-occurring with all sources, investigate the base machine controller and firmware. This article

Preventing Jam Code 14-40 From Recurring

  • Treat the Tray 4–to–Tray 3 inter-unit harness as the highest-risk connector in the entire optional unit stack. Of all the harnesses in an extended LCT installation, the inter-unit harness between the Tray 4 unit and the Tray 3 unit is physically disconnected most often — during every relocation of either unit, every Tray 4 DCSB replacement, and every servicing of the Tray 4 transport section. Each disconnection cycle adds wear to the connector pins and the latch mechanism. On machines above 600k copies or on any machine that has been relocated more than three times, replace the inter-unit harness proactively at the next PM — the cost is a fraction of a callback call for intermittent 14-40. Inspect the connector latch at every PM visit and replace the harness if the latch is broken, since a harness with a broken latch will produce 14-40 within weeks of service
  • Include DCSB-T3 and DCSB-T4 firmware in every firmware update session — without exception. The most common cause of post-update 14-40 is a firmware update session that updated the CPUB and primary engine board but did not include one or both LCT sub-board firmware packages. Before any firmware update session, confirm which firmware packages are required for the complete installation — base machine boards plus all optional unit sub-boards. Download the complete package bundle. Do not leave the machine with the Tray 4 LCT unit powered off during the update session, as powered-off units will not receive their firmware update and will be left at a mismatched version
  • Monitor the Tray 3 pass-through transport rollers for double-wear wear patterns on heavy Tray 4 installations. On machines where Tray 4 is the primary paper source — high-capacity installations where Tray 4 holds the most commonly used paper size — the Tray 3 unit’s pass-through transport rollers receive traffic from both Tray 3 feeds and all Tray 4 feeds. This double wear causes the Tray 3 pass-through rollers to reach replacement threshold faster than Tray 3 feed rollers on the same machine. Worn pass-through rollers do not produce 14-40 (they produce 14-02), but proactive inspection at every PM prevents pass-through roller failure from being overlooked while 14-40 investigation focuses on board communication
  • Clean both DCSB sensor circuits at every PM visit on the Tray 4 LCT unit. The Tray 4 unit’s sensor windows — particularly the Tray 4 feed sensor (PS4 / PS8) and any intermediate VT sensors — accumulate paper dust from the longest paper path in the installation. Paper dust contamination on DCSB-T4 sensor windows causes intermittent false signals that corrupt the WTEN handshake initialization — the DCSB-T4 receives ambiguous sensor data and reports incorrect Tray 4 paper position to the upstream board. A 60-second sensor window cleaning with a dry lint-free cloth at each PM prevents this accumulation on both the Tray 4 unit sensors and the Tray 3 pass-through sensors
  • Document all four firmware versions — CPUB, primary engine board, DCSB-T3, and DCSB-T4 — in the machine service log after every firmware update, and after any DCSB replacement. When a machine with an extended optional cassette stack is called back with 14-40, the ability to immediately read the last-logged firmware state of all four boards from the service log eliminates the most time-consuming diagnostic step. A service log that shows DCSB-T4 firmware at version X after a DCSB-T4 replacement, and a primary engine board update to version Y two months later with no DCSB-T4 entry, immediately identifies the version mismatch without entering Service Mode
  • Never power off the Tray 4 LCT unit independently during a base machine firmware update. On machines where the optional LCT units have independent power connections or power switches, the Tray 4 unit must remain powered on throughout the complete firmware update session. A Tray 4 DCSB that is powered off during a firmware push will not receive its firmware update and will be left at a mismatched version — producing 14-40 the next time Tray 4 is used. Verify that all LCT units are powered on and detected by the base machine before initiating any firmware update

Professional Technician Summary

Jam Code 14-40 — officially categorized as Misfeed at Tray 4 Feed Section in Konica Minolta service documentation — is specifically a Tray 4 image write signal timeout: the paper moved and arrived on time, but the WTEN authorization signal did not reach the engine board before the timeout expired. Despite the “misfeed” category heading, 14-40 is a board-level synchronization failure and is resolved by addressing the controller communication chain — not by replacing any paper transport component in the Tray 4 unit.

14-40 is the most architecturally complex tray-sourced -40 code in the bizhub family. Up to four independent boards carry firmware that must be version-matched: the CPUB, the primary engine board, the Tray 3 DCSB, and the Tray 4 DCSB. Up to three physical harnesses connect those boards: the CPUB-to-engine-board harness, the Tray 3 DCSB-to-engine-board harness, and the Tray 4 DCSB-to-Tray 3 DCSB inter-unit harness. Any single failure in this chain can produce 14-40.

The mandatory first step before any diagnosis is identifying the LCT configuration: dual-cassette single LCT with one shared DCSB (Configuration A), or stacked dual LCT with two independent DCBs in daisy-chain or parallel topology (Configuration B). This identification determines how many DCBs to inspect, which harnesses to trace, and how to interpret the 13-40 + 14-40 co-occurrence pattern.

The fastest diagnostic pathway for isolated Tray-4-only 14-40 is: confirm LCT configuration → inspect and reseat the inter-unit harness (Configuration B) or LCT-to-base harness (Configuration A) → verify DCSB-T4 detected in optional device status in Service Mode → check all four firmware versions → replace DCSB-T4 (Configuration B) or shared DCSB (Configuration A). This sequence resolves the majority of isolated 14-40 faults without base machine board replacement.

For 14-40 + 13-40 with Trays 1 and 2 normal, inspect the Tray 3 DCSB–to–base machine harness first, then replace DCSB-T3 (daisy-chain Config B) or the shared DCSB (Config A). This is the shared harness or shared board failure pattern — one point of failure that cuts off both Tray 3 and Tray 4 communication to the base machine simultaneously.

For post-firmware-update 14-40, firmware reinstall across all four boards in the same session resolves the fault without hardware replacement in the vast majority of cases. The DCSB-T4 firmware version is the most frequently missed element in incomplete update sessions — always confirm it last in the version check sequence.

Document the configuration, the DCSB serial numbers, and all four firmware versions in the machine service log after every service intervention. 14-40 on a revisit call is half-resolved before the technician opens a panel if the service log records exactly which DCBs are installed and what firmware they carry — this is the single highest-value documentation practice for extended optional cassette stack installations.

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