Jam Code 17-20 is a segmented relay checkpoint misfeed within the LCT’s internal transport section on Konica Minolta bizhub production and high-capacity configurations. It belongs to the 17-xx Misfeed at LCT Transport Section family — a code range distinct from the LCT feed section codes (15-01 / 16-01) documented elsewhere in this series, and applicable specifically to large-capacity or production-volume LCT and paper deck units whose internal vertical transport run is long enough to require multiple sequential relay checkpoints rather than the single feed sensor and single vertical transport sensor found on standard 2,500–3,000 sheet LCT units.

On these larger units — commonly found on high-volume production bizhub platforms, and on any configuration where the LCT’s physical height and transport distance from cassette to base-machine handoff exceeds what a single relay sensor can reliably supervise — the internal transport path is divided into segments, each monitored by its own relay checkpoint sensor. The suffix number identifies which checkpoint in this sequence failed to detect paper: 17-10 corresponds to the first relay checkpoint, 17-20 to the second, 17-30 to the third, and so on, with the exact number of checkpoints and their suffix numbering determined by the specific LCT/paper deck unit’s design as documented in its own service manual. A 17-20 fault specifically means paper was confirmed at the first relay checkpoint (17-10’s detection point) but failed to reach the second relay checkpoint within the timing window calibrated for that specific transport segment.

The official Konica Minolta description for this code range states precisely:

Paper confirmed at LCT relay checkpoint sensor 1 was not detected at LCT relay checkpoint sensor 2 within the specified timing window. Paper did not complete transport through this segment of the LCT’s internal vertical transport path.

Translated into field language: this is the identical relay-transport logic documented for the base machine’s shared vertical transport section (20-01) and for the fuser-to-exit relay logic (32-01/32-05), applied specifically to the LCT’s own internal transport run. Large-capacity LCT and paper deck units feed paper from the cassette, through the feed section (covered by 15-01/16-01), and then must carry that paper a substantial vertical distance — sometimes over a meter on the tallest production-volume units — before handing it off to the base machine’s own transport system. This distance is too long, and involves too many individual relay roller pairs, for a single sensor to reliably supervise start-to-finish. The unit’s design instead breaks this run into monitored segments, each with its own entry and exit checkpoint, so that a stall anywhere along the path is isolated to a specific, mechanically narrow segment rather than leaving the technician to search the entire transport height.

17-20 tells the technician something immediately useful before any panel is even opened: paper successfully left the LCT cassette, successfully cleared the feed section, and successfully transported through the first relay segment. The feed roller, separation mechanism, elevator, and first relay roller pair are all confirmed functional. The fault is isolated specifically to the transport hardware between relay checkpoint 1 and relay checkpoint 2 — a narrower, more specific diagnostic zone than would be available on a standard LCT unit with only a single feed-to-VT sensor span.

Field	Details
Jam Code	17-20 (second relay checkpoint in the LCT transport section’s segmented sensor chain; applicable on large-capacity/production LCT and paper deck units with multi-checkpoint transport monitoring)
KM Category Heading	Misfeed at LCT Transport Section — the 17-xx family covers faults occurring within the LCT’s own internal vertical transport run, downstream of the feed section (covered separately under 15-01/16-01) and upstream of the LCT-to-base-machine handoff. The suffix number identifies the specific relay checkpoint segment where the fault occurred
What is confirmed functional when 17-20 fires	LCT elevator, pickup roller, separation mechanism, feed sensor, and the entire first relay transport segment (up to and including relay checkpoint 1 / the 17-10 detection point). None of these require investigation for 17-20. The fault is isolated to the transport hardware between relay checkpoint 1 and relay checkpoint 2 specifically
Critical distinction from 15-01 / 16-01	15-01/16-01 mean paper never left the LCT cassette at all — a feed-section failure. 17-20 means paper DID leave the cassette, DID clear the feed section, and DID transport successfully through the first relay segment — all of that hardware is excluded from suspicion. The fault is specifically in a mid-path transport segment, mechanically distinct from and located further into the LCT unit than the feed section
Critical distinction from other 17-xx suffixes (17-10, 17-30, etc.)	Each suffix isolates a different physical segment of the LCT’s internal transport run. 17-10 (first checkpoint) points to the segment immediately after the feed section. 17-20 (second checkpoint) points to the next segment upstream. Higher suffixes on units with additional checkpoints point progressively further up the transport path, approaching the LCT-to-base-machine handoff. Always confirm the exact number and physical location of checkpoints for the specific LCT/paper deck unit model in its own service manual — the total checkpoint count and physical spacing vary by unit design
Detection Logic:	The LCT controller board (LCTB) monitors each relay checkpoint sensor in sequence. When relay checkpoint sensor 1 confirms paper passage, a timing window begins for paper to reach relay checkpoint sensor 2, calibrated to the known transport distance and nominal relay roller speed for that specific segment. If checkpoint sensor 2 does not trigger within this window, the LCTB reports the segment-specific fault to the primary engine board, which logs 17-20
Key Components	LCT relay checkpoint sensor 1 (17-10 detection point — confirmed triggered, not a 17-20 suspect); LCT relay checkpoint sensor 2 (the sensor whose failure to trigger defines 17-20); relay transport rollers within the segment between checkpoint 1 and checkpoint 2 (pure conveyance rollers, mechanically similar in function to base-machine VT relay rollers); segment-specific drive train (belt or gear linkage from the LCT transport motor to this specific roller segment — may be a dedicated sub-motor on the largest units, or a shared drive from a single LCT transport motor depending on unit design); segment guide plates; LCTB (monitors all checkpoint sensors and manages segment-specific timing windows)
Severity	High — LCT disabled for print; because the fault is segment-isolated, other LCT functions (feed section, other transport segments) may test as fully functional in Service Mode, which should not be mistaken for the whole unit being healthy; paper found stalled within the specific segment between checkpoint 1 and checkpoint 2, typically clean and flat (stalled transport) or crumpled at a specific obstruction point within that segment
Related Jam Codes	17-10 (first relay checkpoint — segment immediately after the LCT feed section), 17-30 and higher (subsequent relay checkpoints further up the transport path, where the specific unit design includes them), 15-01 / 16-01 (LCT feed section misfeed — for comparison, paper never left the cassette at all), 20-01 (base machine shared vertical transport misfeed — the functionally equivalent relay-transport logic applied to the base machine’s own transport section rather than the LCT’s internal path)

Component References

Because the 17-xx segmented relay checkpoint system applies specifically to large-capacity and production-volume LCT/paper deck units, and because the number of segments, their physical spacing, and their exact sensor and roller designations are entirely determined by the specific unit’s design, this article documents the diagnostic logic and inspection method in generic, functionally-named terms. Always confirm the exact checkpoint count, sensor designations, connector references, and Service Mode check codes in the specific LCT/paper deck unit’s service manual before beginning diagnosis — unlike the standard PF-601/602/603-class units documented for 16-01, large-capacity production units vary considerably in their internal transport architecture between models, and no single component table can reliably serve every applicable unit.

Component	Function	Diagnostic Role for 17-20
Relay checkpoint sensor 1 (17-10 detection point)	Confirms paper has entered the transport segment between checkpoint 1 and checkpoint 2	Confirmed triggered — not a 17-20 suspect. Verify in Service Mode only to confirm the segment boundary, not as a fault investigation target
Relay checkpoint sensor 2	Confirms paper has exited the segment between checkpoint 1 and checkpoint 2	The sensor whose failure to trigger defines 17-20. Primary sensor-level investigation target if the segment is confirmed mechanically clear
Segment relay transport rollers	Drive paper through the specific segment between the two checkpoints	Primary mechanical investigation target — inspect for glazing, contamination, and nip pressure exactly as documented for base-machine VT rollers in the 20-01 article
Segment drive train (belt/gear or dedicated sub-motor)	Powers the segment’s relay rollers, either from a shared LCT transport motor or a dedicated motor section on the largest units	Investigate for slip, wear, or failure if roller inspection does not resolve the fault, following the same method as base-machine VT drive train inspection
Segment guide plates	Direct paper through the segment’s transport path	Inspect for displacement, damage, or fragment obstruction using the same multi-angle flashlight technique used throughout this series
LCTB	Monitors all checkpoint sensors and manages segment timing	Verify communication status in Service Mode if a segment-specific I/O check does not behave as expected

ℹ️ Always confirm checkpoint sequence and segment boundaries in the specific unit’s SM before diagnosing 17-20. Large-capacity and production LCT units are not standardized in how many relay checkpoints they use or how their internal transport is physically divided — some units use two checkpoints, others three or more, and the physical distance and roller count within each segment varies by unit model. Before beginning any inspection, locate the checkpoint sensor diagram in the specific LCT/paper deck unit’s service manual and confirm exactly which physical zone lies between the checkpoint 1 (17-10) and checkpoint 2 (17-20) sensors for that unit. Proceeding with a generic “somewhere in the middle of the LCT” search wastes time that a five-minute SM diagram review avoids entirely.

Understanding the Segmented Relay Transport Design — Why 17-20 Occurs

Large-capacity and production-volume LCT units present a transport engineering challenge that standard 2,500–3,000 sheet LCT units do not: the physical distance from the cassette exit to the base-machine handoff point can be substantial — on the tallest production units, exceeding a meter of vertical travel — and this distance must be covered reliably at production print speeds, often exceeding 60–100 pages per minute. A single relay sensor spanning this entire distance would provide the engine board with almost no diagnostic granularity if a stall occurred: the fault code would only be able to say “paper failed to arrive somewhere in this entire multi-hundred-millimeter transport run,” leaving a technician to physically search the full height of the unit for the actual stall point.

The segmented checkpoint design solves this by dividing the transport run into shorter, individually-monitored segments, each with entry and exit detection. This provides two benefits simultaneously: it allows tighter, more accurate timing windows for each individual segment (since a shorter segment has less variance in expected transit time than the full run would), and it gives the fault code itself diagnostic precision — a 17-20 fault immediately tells the technician which specific segment to inspect, without requiring a full-height search of the unit.

Each segment between two checkpoints functions mechanically very much like the base machine’s own shared vertical transport section documented in the 20-01 article: a series of relay roller pairs, driven either by a shared transport motor for the whole unit or by a segment-dedicated motor on the largest designs, carrying paper through guided transport at a constant nominal speed. The failure modes are correspondingly similar — roller wear, drive train degradation, guide obstruction, and sensor faults all apply, adapted to the specific segment’s hardware.

Five root cause categories produce 17-20, ordered by frequency, mirroring the pattern established for the base machine’s shared VT section in the 20-01 article but scoped to this specific segment:

• Category 1 — Paper fragment or foreign object lodged in a segment relay roller nip: Identical in mechanism to the dominant cause of 20-01 — a fragment from a previous jam, not fully cleared, lodges in one of the segment’s relay roller nips and obstructs every subsequent sheet passing through. Given the confined, often less frequently inspected nature of a mid-path LCT transport segment compared to more accessible base-machine transport zones, fragments here can persist undetected longer if a previous jam clearing did not include a thorough inspection of this specific segment. This is the most common cause of sudden-onset consistent 17-20 following any previous jam in or near this segment
• Category 2 — Segment relay roller surface degradation (glazing): The relay rollers within this specific segment have glazed from accumulated cycles, exactly as documented for base-machine VT rollers. Because large-capacity LCT units are frequently deployed in the highest-volume production environments, segment roller wear can accumulate rapidly, and — importantly — different segments along the transport path may wear at different rates depending on their specific roller material, spacing, and load, meaning one segment’s rollers reaching end-of-life does not necessarily indicate the whole unit’s transport hardware is uniformly worn
• Category 3 — Segment drive train fault (belt or gear specific to this segment, or a shared drive fault affecting multiple segments simultaneously): On units where each segment has a dedicated drive sub-assembly, a fault here is isolated to the single segment, producing 17-20 in isolation while other checkpoints (17-10, and any 17-30+) continue to pass normally. On units where a single shared motor drives the entire transport run through a continuous belt or gear train, a fault at any point in that shared drive can potentially affect multiple segments — if 17-20 is accompanied by faults at other checkpoints simultaneously, this points to the shared drive rather than a segment-specific component
• Category 4 — Segment guide plate displacement or damage: A guide plate within this specific segment has been dislodged, most commonly during a previous jam-clearing event where paper spanning this segment was pulled with force. Displacement produces a paper-catch point exactly as documented throughout this series for guide-related failures elsewhere in the paper path
• Category 5 — Relay checkpoint sensor 2 contamination or failure: The checkpoint 2 sensor itself is contaminated or has failed in the OFF state, producing a false 17-20 despite paper having actually transported correctly through the segment. Confirmed by the paper being found at or past the checkpoint 2 location (rather than stalled mid-segment) combined with Service Mode verification showing the sensor fails to trigger on manual paper insertion

Step 1 — Confirm the Checkpoint Sequence and Segment Boundaries for the Specific Unit

Before any physical inspection, confirm exactly which physical zone of the LCT/paper deck unit the 17-20 fault refers to, using the specific unit’s service manual.

1. Identify the exact LCT or paper deck unit model installed (not just the base machine model, since the same base machine can often be configured with different capacity LCT options)
2. Locate the checkpoint sensor diagram in that unit’s service manual, confirming the physical location of relay checkpoint sensor 1 (17-10) and relay checkpoint sensor 2 (17-20), and the specific transport hardware (roller count, drive source) that lies between them
3. Note whether this unit uses additional checkpoints beyond 17-20 (17-30 and higher), and their locations, for context on where this segment sits within the overall transport run — this helps set expectations for how much of the total transport height remains unaccounted-for if 17-20 is resolved but a different checkpoint fault appears on a subsequent job

Step 2 — Clear the Paper, Confirm the Stop Position Within the Segment, and Classify the Pattern

1. Open the LCT transport access panel(s) covering the specific segment identified in Step 1, per the operator panel jam indicator and the unit’s SM access procedure
2. Observe paper position before removal:
   • Paper found flat and stationary within the segment, not reaching checkpoint 2: Points to Category 1 (fragment obstruction), Category 2 (roller glazing), or Category 3 (drive train fault). Proceed to Steps 3 and 4
   • Paper found crumpled or folded at a specific point within the segment: Points to Category 1 (fragment/obstruction) or Category 4 (guide plate displacement) at that specific fold location. Proceed to Step 3 with attention to that exact location
   • No paper found within the segment, or paper found at/past the checkpoint 2 location: Points to Category 5 (checkpoint 2 sensor fault). Proceed to Step 5
3. Remove jammed paper carefully in the direction of travel. Inspect the segment with a flashlight at multiple angles for fragments, exactly as documented throughout this series, paying particular attention to this specific segment’s roller nips and guide junctions, since this zone may not have been inspected as thoroughly during a previous, more cursory jam-clearing pass

Step 3 — Inspect Segment Relay Rollers and Guide Plates

1. With the unit powered off, access the segment’s relay rollers per the unit SM. Inspect each driven roller for glazing (shiny, smooth, hard surface versus matte, tacky new-roller texture), contamination, and damage, using the identical criteria established for base-machine VT rollers in the 20-01 article
2. Inspect each pinch/idler roller for spring return force and free rotation, using the same push-and-release and hand-spin tests documented throughout this series
3. Inspect all guide plates within the segment for correct seating, displacement, or damage, using the same multi-angle flashlight technique and mounting-tab verification method documented for guide plates elsewhere in this series
4. Clean or replace any roller or guide found deficient. Run a test job feeding paper specifically from the LCT to confirm 17-20 does not recur before proceeding further

Step 4 — Verify the Segment’s Drive Train

1. Command the segment’s drive motor (shared LCT transport motor, or a dedicated segment sub-motor on units so equipped) in Service Mode I/O check, and observe whether the segment’s rollers rotate correctly and consistently
2. If the drive is shared across multiple segments, check whether other checkpoints (17-10, 17-30+) are also producing faults — simultaneous multi-segment faults point to the shared drive itself rather than any single segment’s components, exactly as the equivalent diagnostic logic applies to the base machine’s M1/M22 shared drive in the 20-01 article
3. Inspect any accessible belt or gear components specific to this segment for wear, slippage, or damage, following the same inspection method documented for base-machine VT drive trains
4. Replace or repair any confirmed drive fault per the unit-specific SM procedure

Step 5 — Verify Relay Checkpoint Sensor 2 in Service Mode

1. Enter Service Mode and locate the checkpoint 2 sensor’s I/O check for the specific unit. Verify state with the segment confirmed physically clear: OFF indicates correct function; ON indicates a stuck sensor requiring cleaning, actuator inspection, or replacement
2. Manually insert paper into the sensor’s detection zone and verify it toggles to ON and back to OFF on removal — the standard two-way test used throughout this series
3. Reseat the sensor’s harness connector at the LCTB before considering replacement
4. Replace the sensor if it remains non-responsive after cleaning and connector reseating

Quick Reference — Troubleshooting by Symptom

Symptom	Most Likely Cause	First Action
17-20 appeared immediately after clearing a previous jam anywhere in the LCT transport path	Paper fragment lodged in a relay roller nip within this specific segment, possibly missed during a less thorough previous clearing	Inspect this segment’s roller nips and guide junctions specifically with a flashlight at multiple angles; remove any fragment; retest
17-20 only, no other checkpoint faults (17-10 and any 17-30+ pass normally)	Fault isolated to this specific segment’s rollers, guides, or dedicated drive sub-assembly (on units so equipped)	Inspect this segment’s rollers and guides per Step 3 before considering any shared-drive or LCTB-level cause
17-20 together with faults at other checkpoints (17-10 and/or 17-30+) simultaneously	Shared drive fault (motor, belt, or gear serving multiple segments) rather than a single-segment issue	Investigate the shared LCT transport drive per Step 4 rather than treating each checkpoint fault as an independent single-segment cause
17-20 intermittent, escalating over weeks	Progressive relay roller glazing within this segment	Inspect segment roller surfaces for early-stage glazing; replace proactively rather than waiting for full consistent failure
17-20 with no paper found within the segment; checkpoint 2 sensor reads ON in Service Mode with path clear	Checkpoint 2 sensor stuck ON	Inspect actuator and sensor window for contamination or jam; clean; reseat harness; replace sensor if stuck-ON persists
17-20 with paper found crumpled at a specific, repeatable point within the segment across multiple jam events	Displaced or damaged guide plate at that specific location	Inspect and reseat the guide plate at the identified fold location; replace if cracked or unable to hold correct seating

Understanding the 17-xx Segmented LCT Transport Checkpoint Family

Jam Code 17-20 belongs to the 17-xx family of segmented relay checkpoint codes covering the LCT’s internal transport section on large-capacity and production-volume units. Unlike the simpler feed-section-only scope of 15-01/16-01, this family exists specifically because these units’ transport runs are long enough to warrant multiple, individually-monitored segments:

• 17-10 — First relay checkpoint — covers the segment immediately following the LCT feed section (the zone between the feed sensor, covered under 15-01/16-01, and the first relay checkpoint). A fault here suggests investigating the earliest portion of the internal transport run, closest to the cassette
• 17-20 — Second relay checkpoint — covers the segment between the first and second relay checkpoints. Confirms the feed section and the first transport segment are functioning correctly; isolates the fault to this specific mid-path segment. This article
• 17-30 and higher (unit-dependent) — Subsequent relay checkpoints, where the specific unit’s design includes additional segments, progressively closer to the LCT-to-base-machine handoff point. Consult the specific unit’s SM to confirm how many checkpoints exist and their exact physical locations

This segmented structure is functionally analogous to the two-checkpoint system documented for the base machine’s paper exit section (32-01 for the fuser-exit checkpoint, 32-05 for the subsequent output/exit checkpoint) but extended to however many segments a specific large-capacity LCT unit’s transport height requires. The core diagnostic principle is identical across all of these segmented systems throughout this series: a fault at a given checkpoint confirms every upstream checkpoint’s hardware as functional, and isolates the investigation to the specific segment between the last-confirmed checkpoint and the failed one.

Preventing Jam Code 17-20 From Recurring

• Include a full-height inspection of the LCT’s internal transport path in every jam-clearing event, not just the segment where the jam indicator points. Because segmented transport paths can hide fragments in less-obviously-affected segments, a jam-clearing pass that only addresses the immediately indicated zone can leave debris elsewhere in the unit that surfaces as a different checkpoint’s fault on a later job
• At every PM on large-capacity/production LCT units, inspect and clean relay rollers and guide plates across every segment, not only the segment most recently associated with a reported fault. Given that different segments can wear at different rates depending on their specific hardware and load, a PM that only attends to a previously-faulted segment risks missing early wear developing elsewhere in the transport run
• Document which specific checkpoint(s) have faulted over the service history of a given unit, tracking patterns by segment. A unit that repeatedly produces 17-20 specifically (rather than faults spread across multiple checkpoints) points to a segment-specific hardware weakness — worn rollers, a marginal drive component, or a guide plate design issue at that location — that may benefit from a targeted proactive replacement rather than routine wait-for-failure servicing
• Confirm the specific unit’s checkpoint diagram is on file or readily accessible before a service visit is needed, since the variety of large-capacity LCT and paper deck designs in the field means a technician should not assume familiarity with any given unit’s exact segment layout without confirming it against that unit’s own SM

Professional Technician Summary

Jam Code 17-20 is a second relay checkpoint misfeed within the segmented internal transport section of a large-capacity or production-volume LCT unit — paper was confirmed passing the first checkpoint but failed to reach the second within the timing window for that specific segment. This confirms the LCT’s feed section and the first transport segment are fully functional, narrowing the entire diagnostic scope to the specific mechanical zone between the two checkpoints.

The first action on any 17-20 call is confirming the exact segment boundaries for the specific unit installed, since large-capacity LCT and paper deck designs are not standardized in checkpoint count or physical layout the way standard-capacity LCT feed sections are. A five-minute review of the unit’s own SM checkpoint diagram before opening any access panel focuses the entire remaining investigation correctly.

The diagnostic logic mirrors the base machine’s shared vertical transport section (20-01) applied to a specific, narrower zone: check for a fragment first (the most common cause, especially following any prior jam in the area), inspect segment rollers for glazing, verify the segment’s drive train, and check the checkpoint 2 sensor last if the segment is confirmed mechanically clear. Whether the fault is isolated to this segment alone or accompanied by faults at other checkpoints simultaneously immediately distinguishes a single-segment component failure from a shared-drive fault affecting the whole unit — check for this pattern early, as it directs the entire remaining repair.