A ceramic line stops with a band of missing colour in one channel. The operator reports “the head is dead”. Someone orders a printhead. Three days later the new head is fitted, the band is still there, and the real fault turns out to be in the driver electronics. The reverse also happens: a board is replaced when the fault was a partially blocked nozzle row all along.
On HOPE and TECNOFERRAR ceramic printers running Xaar 1002 or Xaar 1003 heads, the printhead and its HPC3 HV driver assembly share the same electrical path, so a failure in either one produces almost the same symptom on the tile. This guide gives maintenance engineers a structured way to separate an HPC3 XP55500036 board failure from a printhead failure before any money is spent, using evidence the machine already produces.
Why board faults and printhead faults look identical
Inkjet fault-finding goes wrong when the technician starts from the part instead of from the signal. A printhead needs three things to fire a nozzle: a correctly formed drive pulse, ink at the right pressure at the nozzle, and a nozzle that is physically clear. The HPC3 HV assembly supplies the first. The ink system supplies the second. The nozzle plate and its internal channels decide the third.
When the print result loses nozzles, all three causes collapse into the same visual evidence: gaps in a nozzle test pattern and white lines on the finished product. That is why the diagnostic order matters more than the diagnostic tools. If you replace the printhead first, you have not tested anything — you have simply changed one variable and hoped.
Collect the evidence before you touch hardware
Record the error log exactly as it appears
Machine builders word their alarms differently, and the same physical fault can be reported as a head error, a data error, a temperature error or nothing at all. Copy the alarm text verbatim into the maintenance log with the date, the machine state (cold start, mid-shift, after a head swap) and the channel involved. A fault that appears only within the first minutes after power-on is telling you something different from a fault that develops after two hours of production.
Print a nozzle test on a file you trust
Use a fixed test pattern, not a production job. Production artwork hides small nozzle losses inside busy detail. Print the same pattern before and after every intervention and keep the sheets. This single habit converts vague descriptions like “quality is poor” into a comparable record, and it is the fastest way to prove whether a change you made actually changed anything.
Four symptoms that point to the HPC3 board
1. The same defect appears in more than one colour
A printhead is a single physical unit with its own nozzle rows. If the identical gap pattern turns up in two colours, one printhead cannot be the cause — unless the two colours share the same head, which you should confirm from the machine’s head layout before going further. Look for a fault that follows an electrical channel or a connector rather than a physical head position.
2. The nozzle loss survives a head swap
This is the most valuable test available to you, and it costs only time. Move the suspect printhead to a different position on the same bar, or fit a known-good head into the suspect position, then reprint the nozzle test.
- If the defect stays at the position, the head is not the problem. The wiring, connector or driver channel serving that position is.
- If the defect travels with the head, the head is the problem and the board is probably fine.
3. A channel is dead from a cold start
Electronics that have failed outright usually fail immediately and repeatably. A channel that produces nothing on the very first test of the day, before any ink has had time to settle or any temperature drift can develop, behaves like an electrical open circuit. Compare that with a head that prints acceptably for twenty minutes and then fades — the second pattern is much more typical of an ink-feed or thermal problem.
4. Other functions on the same assembly misbehave
An HV driver assembly does more than fire nozzles. If you also see intermittent data errors, head identification problems, or a position that drops out and returns without any mechanical intervention, the evidence is accumulating against the electronics rather than the fluid path.
Four symptoms that point to the printhead
1. One colour, one position, always the same nozzles
A stable, repeatable set of missing nozzles in a single head is the classic printhead signature. It is also the signature of a partial blockage, which is why the next check is fluid, not electrical. The clogging mechanisms that produce this pattern — pigment settlement, dried ink on the nozzle plate, ceramic dust, incorrect negative pressure — are covered in detail in our guide to why ceramic printheads clog, and that article is the right place to start if the fault is ink-side.
2. The fault moves when you move the head
Any defect that relocates with the physical head has already answered the board-versus-head question. The remaining work is deciding whether the head can be recovered by cleaning or has to be replaced.
3. The defect responds to purging, wiping or a rest period
If a nozzle recovers after a purge and then degrades again over hours, air is entering somewhere or the nozzle is partially restricted. Electrical faults do not improve after a purge. This is a strong, cheap discriminator that many teams skip because purging feels like it might “waste ink” — the information is worth far more than the ink.
4. The problem started after an ink or filter change
Trace the timeline. A fault that begins within a shift of a filter replacement, an ink batch change or a cleaning-fluid flush points to contamination or incompatibility in the fluid path, not to a board that has been running for months without complaint. Be equally suspicious of a fault that appears after someone reseated connectors during maintenance — in that case both explanations remain open.
A 20-minute test sequence that settles the question
Run these steps in order and stop as soon as the evidence is conclusive. Each step changes exactly one variable.
- Print the reference nozzle test and photograph it. Note which positions are affected.
- Purge and reprint. Recovery means fluid. No change means the fault is stable and can be investigated further.
- Reseat the data and power connections at the HPC3 assembly for the affected position, then reprint. A fault that disappears after reseating is a connection fault, and it will return — plan to replace the harness or connector rather than declaring the machine fixed.
- Swap the head to another position. Confirm whether the defect travels with the head or stays with the position.
- Only then order the part the evidence supports.
What to inspect on the HPC3 XP55500036 assembly itself
Connector and ribbon condition
Unplug the assembly with the machine isolated, then inspect the ribbon contacts and the connector housing for fretting, corrosion, ink mist residue or a partially backed-out pin. Ink mist is conductive enough to cause intermittent faults on industrial printers, and it accumulates silently inside cabinets that are never opened between services.
Signs of thermal or fluid damage
Look for discolouration around components, bulged capacitors, a smell of hot electronics, or dried ink bridging tracks. Any of these is sufficient reason to replace the assembly rather than keep diagnosing around it. Photograph what you find before removing the part — the photo is often what a supplier needs to confirm you are ordering the right item.
Part number and revision confirmation
The HPC3 XP55500036 board card is described by Lemsun Tech as an original and new HOPE TECNOFERRAR XAAR 1002 HPC3 HV assembly, a printhead driver board card for Xaar 1002 and 1003 printheads in ceramic printing machines. Because the same machine family can be built with different revisions, confirm the number printed on your existing board and the exact machine model before ordering, and keep a photo of the label on file.
What not to do while diagnosing
- Do not swap a printhead and a board at the same time. You will fix the machine and learn nothing, and the next failure will start from zero.
- Do not judge a head by its appearance. A clean-looking nozzle plate can still have restricted internal channels, and a discoloured board can still be electrically sound.
- Do not reuse a printhead that failed on a suspect channel without testing it on a known-good position first. You may be scrapping a serviceable part, or you may be installing a fault into a healthy slot.
- Do not treat a reseated connector as a repair. Intermittent connections fail again, usually during a rush order.
Where the Firepulse card fits in
Not every electrical fault lives on the HV assembly. On system printers, the pulse card is a separate component with its own failure modes, and the symptoms it produces overlap with both head and board faults. If your machine uses a Firepulse card, work through the Firepulse card 1902400020 failure symptoms before assuming the HPC3 assembly is at fault, so that you are not diagnosing one board by replacing another.
When it is time to replace the printhead instead
Once the head has been proven guilty — the defect follows it across positions, cleaning and purging do not hold, the nozzle plate shows physical damage, and the ink supply has been verified — replacement is the economic answer. Fit the exact model the machine uses. The Xaar 1003 family runs 1,000 nozzles at 360 npi in both variants, but the GS6C covers a 6–42 pL drop range while the GS12C covers 30–80 pL, and a head chosen for the wrong ink laydown will print a different result even when it is mechanically perfect. Our Xaar 1003 replacement walkthrough covers the handling and start-up steps that decide whether a new head survives its first week.
Frequently asked questions
Can a faulty HPC3 board damage a good printhead?
An HV assembly that is delivering an incorrect drive signal is not a healthy environment for any head, which is one reason to resolve a proven board fault before fitting a new printhead. Confirm the specific risk with the machine builder for your model; the electrical limits are machine-specific and are not published on our product page.
How long should a head swap test take?
On most ceramic lines the mechanical swap is under half an hour, and the nozzle test adds a few minutes. That is far less than the cost of a wrongly ordered part, which is why the test should come before the purchase order rather than after.
Is a board fault always accompanied by an alarm?
No. Partial channel failures can print badly with no alarm at all, because the machine only knows that data was sent, not that ink left the nozzle. This is why the printed nozzle test remains the most reliable single piece of evidence you have.
Do you supply both parts?
Lemsun Tech supplies printheads, driver boards, pumps, degassing membranes and filters for industrial ceramic and corrugated printing equipment. Send your machine model, the part number from the existing component and a photo of the label, and the team can check compatibility before shipment.
Not sure which part is failing? Send us your nozzle test pattern, the alarm text and a photo of the HPC3 label through our contact page, and we will help you narrow it down before you order.
Post time: Nov-08-2026