The encoder, measuring wheel, pulse input and print-length registration control are part of the operating sequence, and their condition can contribute to artwork that stretches, compresses, drifts in the feed direction or returns to position after a stop.
Final limits, parts and adjustments remain configuration-specific; use the delivered encoder and printer documentation, RIP job record and permitted substrate setup values instead of applying a universal value.
Start with job and component identity
Write down encoder model and resolution, measuring circumference, input channel, transport section, artwork job and substrate lot. Mark when the concern appears during job start, constant speed, speed change, restart and the transition between material rolls or stacks. Include the operator observation, machine state, material or job identity and the last known acceptable operating period. This prevents several different faults from being grouped under one general alarm or quality description.
Distinguish fixed scale error from accumulating drift
| Observed condition | Evidence to collect | Diagnostic direction |
|---|---|---|
| Image length is consistently scaled | RIP dimensions, intended repeat length and measured output | Artwork scale, encoder factor or circumference |
| Error grows through the run | Sequential print measurements and pulse or position trace | Slip, lost pulses or transport stretch |
| Registration shifts after acceleration | Speed profile, encoder contact and drive status | Wheel slip, tension transition or control response |
| Random narrow bands are displaced | High-resolution defect map and signal wiring observation | Pulse noise, intermittent contact or data issue |
| One substrate behaves differently | Thickness, surface, coating and measuring-wheel condition | Contact traction or material stretch |
The diagnostic directions are possibilities to investigate, not confirmed causes. Compare observations with the actual circuit, tooling and component documentation before replacing a part or changing a setting.
Control hazardous energy and preserve references
Apply the site lockout and isolation procedure for electrical, pneumatic, vacuum, thermal, gravity and stored mechanical energy that applies to this equipment. Verify the zero-energy state before guards, terminals, tubing, tooling or drive components are accessed. Hot surfaces and charged electrical parts may remain hazardous after the machine stops.
Photograph connectors, tube routing, witness marks, adjustment positions, wiring labels and component orientation before disassembly. Qualified personnel should perform live electrical or pressure measurements only when the permitted diagnostic procedure specifically requires them and appropriate controls are in place.
Inspect the component in its complete load path
Corroborate the digital file and RIP scale first, then examine encoder mounting, measuring-wheel cleanliness and pressure, cable shielding, connector condition, transport tension and substrate traction. Avoid changing calibration to compensate for an unverified artwork file.
Compare the affected component with the related substrate feeding and transport guide before deciding that one observation identifies the cause.
Verify the repair in stages
Before power or pressure is restored, corroborate tools are removed, connections are secure, guards are reinstated and the work area is clear. Use the defined manual, jog or slow-cycle test first, then progress through small controlled operating stages while watching the original symptom and any secondary effect.
Print a controlled reference pattern at staged speeds, label sheets or web sections in order, measure image length and register from fixed marks, and retain the job setup values with the encoder evidence. Do not release the machine based only on one acceptable cycle. Document the parts or setup values changed, final observations, retained samples and the person authorized to return the equipment to production.
Can the encoder factor be changed to fix one artwork file?
Not before the file scale and repeat setup values are verified; otherwise all other jobs may be affected.
Does a clean signal prove that the measuring wheel is not slipping?
No. Electrical pulses can be clean while mechanical contact fails to represent actual substrate travel.
Why compare different speeds?
A speed-dependent error helps separate fixed scaling from traction, tension or dynamic control behavior.
What should accompany printed samples?
Include source dimensions, RIP setup values, substrate identity, speed, sequential measurements, encoder mounting photos and signal observations.
Send the machine model, component identity, labeled samples, sequence video, observed values and service history through our inquiry page. HANNAI can review the evidence against the delivered machine configuration.