Quick verdict
Most print faults have a simple first check. Run a nozzle check before anything else: missing nozzles mean cleaning, while even bands across all colours mean feed calibration. Check that HP Latex white printheads are installed, not in storage. Wait about 24 hours before laminating eco-solvent prints. Use primer on glass, cast acrylic, stainless steel and aluminium. Never switch off a Roland printer's main power over a long holiday. If the first fix does not work, call an engineer before parts are damaged.
This guide collects the faults DPI Technology's engineers are called out for most often across Malaysia, on HP Latex, Roland DG, LDP and OEM printers. Find your symptom in the table, try the first fix, and contact us if it does not clear.
Find your problem
| Symptom | Most likely cause | First fix | Call DPI if |
|---|---|---|---|
| Lines or bands in one or two colours | Blocked or misfiring nozzles | Nozzle check, then normal cleaning | The same colour rows stay missing after two cleanings |
| Even bands across all colours | Media feed calibration | Run feed (step) calibration for that media | Bands change with print direction or speed |
| HP Latex W printer prints no white | White printheads in storage, or no white in the job | Install the white printheads; check the white layer in the RIP | White is still missing with heads installed |
| Thick ink, warnings or poor curing | Expired or badly stored ink | Replace the expired ink | Ink lines or dampers need washing |
| Many clogs after a long holiday | Main power switched off; heads dried | Cleaning cycles and a nozzle check | Nozzles do not recover after cleaning |
| Bubbles, gummy adhesive or lifting edges after laminating | Eco-solvent print laminated too soon | Dry prints about 24 hours before laminating | It happens on dry prints too |
| UV ink peels off cast acrylic, glass or metal | Surface needs primer or degreasing | Degrease, then print primer first | Ink still lifts after primer |
| Media wrinkles or warps in an HP Latex printer | Curing temperature too high for the media | Lower the curing temperature in small steps | Ink stays wet at a lower temperature |
| Reds, oranges or brand colours will not match | Wrong ICC profile or limited ink gamut | Use the correct media profile; consider an orange and red ink set | Colour drifts between jobs |
Banding lines
Print a nozzle check first, because it tells you which kind of banding you have.
- Gaps in one or two colours: nozzles are blocked or misfiring. Run a normal cleaning and check again. If the same rows stay missing after two cleanings, stop. Repeated powerful cleanings waste ink and can damage the head. The cause may be a blocked damper, an ink-supply fault or a head that needs an engineer.
- Nozzle check is perfect, but bands run across every colour at even spacing: the media advance is wrong. Run the printer's feed or step calibration for that media and save it to the media preset.
- Bands on a wide UV printer such as the LDP 3.2 m in only some colours: treat it as a head or ink-supply fault and call us. Do not swap heads or boards by trial and error.
HP Latex white ink not printing
On HP Latex W printers, the white printheads can be kept in storage to extend their life. If a job with white is sent while they are out of the carriage, the printer logs an error but keeps printing, without white. Install the white printheads as the control panel instructs, then reprint.
If the heads are installed, check the job. The white layer must be set in the RIP, using the white mode you need, such as underflood or overflood. After a long shutdown, HP's recovery procedure for the Latex 700 and 800 series allows 48 hours for white ink recirculation before printing. See also our HP Latex 730W page.
Expired ink and ink storage
Roland warns that expired ink can thicken, cause discharge problems and lower print quality, and that hardened ink can cause malfunctions. The printer may also show an "INK SHELF LIFE EXPIRE" message. Replace expired ink rather than running it out. Roland's BD-8 manual gives a storage range for unopened cartridges of 5 °C or higher and below 40 °C, so do not leave ink in a hot car or by a window. If ink has thickened in the lines, the tubes and dampers may need washing by an engineer.
Preventing clogs over Chinese New Year and Hari Raya
Most post-holiday clogs we see come from switching the printer off. Roland's instructions for long idle periods are clear:
- Never switch off the main power, so automatic maintenance keeps running.
- Do not let the printer run out of ink or cleaning liquid, or it cannot run automatic maintenance.
- Empty the drain bottle before you leave.
- Switch off the dryer.
- When you return, print a nozzle check and clean only the heads that need it.
If your shop cannot keep the power on, talk to us before the holiday. HP Latex 700 and 800 series printers have their own extended-downtime procedure, which we can carry out with you.
Bubbles after laminating eco-solvent prints
Eco-solvent ink keeps releasing solvent after printing. 3M's Instruction Bulletin 4.22 gives about 24 hours of drying for solvent-based inks, and the printer's heaters do not dry them fully. Laminate too early and the trapped solvent shows as bubbles, a soft or gummy adhesive, or lifting edges. In Malaysian humidity, allow longer and spread prints out rather than rolling them tightly. Latex prints come out dry, and 3M advises laminating UV prints between 1 and 72 hours after printing.
UV ink peeling off the substrate
UV ink sits on the surface, so smooth, non-porous materials need help. Roland recommends a primer for glass, enamel, cast acrylic, tile, stainless steel and aluminium, and notes it has no effect on copper or brass. Degrease the surface before printing and avoid touching it with bare hands. If ink peels when a decal is removed from a printed sign, the primer was missing or the surface was not clean. Test adhesion on an offcut before a full job. For ink choice, read EUV-HP vs EUV-A7.
Media wrinkling in an HP Latex printer
Latex ink is set by heat, and some thin or heat-sensitive films deform in the curing zone. Choose the correct media preset first. If the media still wrinkles, lower the curing temperature in small steps until it stops. If the ink is then not fully dry, use a slower print mode or more passes rather than raising the heat again.
Colours that will not match
Most colour problems come from the wrong ICC profile for the media, or from a profile made with different ink. Print with the exact profile for your media and print mode. For brand reds and oranges, an ink set with orange and red widens the gamut; see TA2 ink explained.
Still not fixed? WhatsApp a photo of the nozzle check and the fault to +60 16-360 3588, Monday to Friday, 9:00 am to 5:30 pm. DPI engineers service HP Latex, Roland DG, LDP and the OEM printers we supply, with spare parts stocked in Malaysia.
Frequently asked questions
Why does my printer show banding lines?
Print a nozzle check. Missing nozzles in one or two colours mean blocked or misfiring nozzles, which need cleaning. A perfect nozzle check with even bands across all colours means the media feed needs calibrating.
Why is my HP Latex 730W or 830W not printing white?
The white printheads are probably in storage. The printer logs an error but keeps printing without white. Install the white printheads, then check that the job has a white layer set in the RIP.
How long should eco-solvent prints dry before laminating?
About 24 hours, according to 3M's Instruction Bulletin 4.22, and longer in humid conditions. Laminating too early causes bubbles, a gummy adhesive and lifting edges.
Can I use UV ink after its expiry date?
Roland recommends replacing expired ink. It can thicken, cause discharge problems, lower print quality and harden in the printer.
How do I stop printheads clogging during a long holiday?
On Roland printers, keep the main power on so automatic maintenance runs, keep enough ink and cleaning liquid in the printer, and empty the drain bottle before you leave. Print a nozzle check when you return.
Why does UV ink peel off acrylic or metal?
Smooth, non-porous surfaces need degreasing and a primer. Roland recommends primer for glass, cast acrylic, tile, stainless steel and aluminium; it has no effect on copper or brass.
Why does my media wrinkle in an HP Latex printer?
The curing temperature is too high for that media. Use the correct media preset and lower the curing temperature in small steps, using a slower print mode if the ink is not fully dry.
Sources: 3M Instruction Bulletin 4.22 · Roland DG: printer not in use for a prolonged period · Roland DG: primer printing · Roland DG: ink shelf life · Roland DG: ink cartridge storage · HP: Latex 700 and 800 recovery after extended downtime · Caldera: HP Latex 730 and 830 W printer settings
