EHT Trip error on a Videojet 1620/1880 — 7 causes and a step-by-step repair
MM
Mikołaj Małecki
Owner of MMTech INK-JET · 10 years in the CIJ industry
⏱ 8 min read
Updated 22 April 2026
✓ Verified by MMTech specialists
TL;DR · in three sentences
EHT Trip means the high-voltage protection has tripped — the printer detected an arc between the deflector plates and cut the power itself. In 70–80% of cases it is enough to clean the electrodes, dry the printhead chamber and restart; the procedure takes 15 minutes.
When this article is for you
On screen: "EHT Trip" or "High Voltage Off"
The log shows the flag Bit 6: EHT TRIP (ESI/WSI protocol)
The printer stopped suddenly and without warning — no jet, no printing
The error returns after restart attempts
01 · Repair procedure
Open the printhead, clean it, restart
The procedure below works for the Videojet 1620, 1880 and most other 1000-series models (1520, 1550, 1580, 1610, 1710). If you are doing it for the first time, allow 30 minutes and have to hand: the original Videojet cleaning solvent, lint-free technical wipes, nitrile gloves and safety glasses.
⚠ Safety warning
The deflector plates carry a voltage of 5–8 kV DC. After the printer is switched off the capacitors discharge within 2–3 minutes. Never touch the electrodes immediately after switching off. Always wait a full 5 minutes before cleaning and confirm there is no voltage.
1
Stop the jet and switch the printer off
Press Stop Jet on the panel. Once the jet has stopped (15–20 s), switch the printer off at the main switch and unplug the power cable. Wait 5 minutes for the high-voltage capacitors to discharge.
2
Open the printhead housing
Remove the printhead cover — on the Videojet 1620/1880 this is a flap on a magnetic hinge. The deflector plates and the charge electrode are accessible in the printhead tunnel section.
3
Inspect the electrodes and the chamberCheck visually
Dark deposits on the edges of the deflector plates, wet ink, condensation or streaks of dried ink all point to the first of the most common causes (see the table in section 02). Take a photo with your phone before cleaning — it is useful if you later raise a service request.
4
Clean the electrodes with solvent
Soak a lint-free wipe in Videojet solvent (or the MMTech replacement 21-01-401 (OEM part 201-0001-401) compatible with the ink in your printer). Wipe in turn: the deflector plates (the facing surfaces), the charge electrode and the gutter housing. Use single-direction strokes, do not scrub.
5
Dry the chamberCritical step
Solvent left between the deflector plates will itself create an arc at 5–8 kV, and EHT Trip will return within 30 seconds of the restart. Dry with a gentle stream of compressed air through a filter (oil-free, otherwise you will blow in an oil mist) or simply wait 10 minutes.
6
Close the printhead, switch on, start the jet
After the restart the printer will auto-phase (30–60 s). If the jet returns correctly, run a test print on 10–20 products and watch whether EHT Trip comes back.
7
Monitor for 2 hours
If EHT Trip does not return, the problem is solved — record the date in the service log. If it comes back once or several times, go to section 02 and read about the remaining six causes; the problem is most likely deeper.
If EHT Trip returns after cleaning
Do not tinker with the HV power supply. This is not something to tackle yourself.
The high-voltage circuit in a Videojet has a 44 MΩ resistor inside the umbilical cable. A fault in that resistor produces exactly the same symptoms as dirty electrodes. Only a multimeter measurement with a suitable range will tell them apart. Contact an authorised CIJ printer service in your region. If you need premium replacement inks or solvents after the faulty component has been replaced, get in touch with us.
02 · Seven causes of EHT Trip
What is really happening behind the alarm
EHT Trip (Extra High Tension Trip) is a current spike in the high-voltage circuit detected by the CSB (Control Status Board). With the flag Bit 6 in the binary ESI/WSI communication the printer signals the event, and the software immediately cuts power to the deflector plates. This is not a failure but a protection that prevented more serious damage. The question that remains is what caused the current spike.
From the reports handled by our technical department between 2020 and 2025 (Videojet 1000 series — remote diagnostics and consultations) we classified the cases into seven categories, ordered by how often they occur.
01
Dirty deflector electrodes
Dried ink deposits form a conductive bridge between the plates.
~55%
02
Moisture condensation in the printhead chamber
After CIP line washing, or in humid halls, dew settles on the electrodes.
~18%
03
Satellite droplets
An unstable break-off point (low viscosity) generates micro-droplets that fall onto the plates.
~10%
04
Damaged insulation in the umbilical cable
An internal break in the high-voltage conductor: resistance deviates from 44 MΩ.
~7%
05
ESD (electrostatic discharge)
A one-off external event: static from the product or the conveyor belt.
~5%
06
Faulty high-voltage power supply board (PN 399081)
Worn capacitors or a damaged transformer: the board must be replaced.
~3%
07
CSB (Control Status Board) failure
Incorrect current readings: false alarms despite a healthy power supply.
~2%
A Pareto distribution: the first two causes account for over 70% of cases, and the first three — over 80%. That is why the procedure in section 01 starts with cleaning the electrodes and drying the chamber — statistically the most worthwhile action.
03 · Why it happens
The physics of arcing in the printhead chamber
To prevent EHT Trip rather than merely react to it, it helps to understand exactly what happens between the deflector plates. This section is optional — if your line is down, come back to it later.
How the droplet stream forms and where satellite droplets come from
A CIJ printhead forces ink through a sapphire or ruby nozzle 40–70 micrometres across at 2–5 bar. The jet travels at 5–10 m/s. In the resonator chamber a piezoelectric crystal vibrates at 60–100 kHz, breaking the jet into regular droplets.
When ink viscosity falls below nominal — in hot weather, say, or after too much solvent has been added — the break-off point shifts. Instead of even droplets you get clusters: a main droplet with a trailing "satellite" micro-droplet. These satellites are too small to carry the correct charge, so instead of reaching the gutter they fall freely under gravity, straight onto the deflector electrodes.
Why moisture in the chamber causes arcing
Dry air is an excellent insulator: for an arc to jump at 7 kV between plates a few millimetres apart takes exceptional condensation or ionisation. Water droplets change that dramatically. Water has a dielectric constant of about 80 (dry air: 1.0006), which means even a microscopic layer of condensation sharply lowers the breakdown voltage of the air.
In food production halls, especially after CIP washing, relative humidity regularly exceeds 80%. The printhead chamber is cooler than the hall (the electronics are cooled), so water vapour condenses on the cooler surfaces — exactly where the high-voltage electrodes work.
What the 44 MΩ resistor in the umbilical does
The umbilical cable linking the printer controller to the printhead contains an internal resistor of about 44 MΩ (typical tolerance ±5%, so 41.8–46.2 MΩ). Its job is to limit the current flowing to the deflector electrodes in the event of any short. If an arc jumps, the resistor limits the current spike to a safe level, the CSB picks that spike up and raises EHT Trip.
When the umbilical has been bent too sharply over the years or damaged mechanically, the resistor can go open circuit (resistance rises towards infinity) or short (resistance falls). Both produce false EHT Trips: the printer cannot tell whether the current spike came from an arc in the chamber or from an anomaly in the resistor. A multimeter measurement is the only certain diagnosis; a resistance outside the ±5% tolerance means the umbilical must be replaced.
04 · How to prevent it
Three habits that eliminate 80% of cases
Clean the electrodes every 200 operating hours (or weekly on a 24/7 line). The procedure from section 01 without step 1 — done without stopping the jet, from Service mode. Five minutes of operator time and cause number one is gone.
Keep ink viscosity stable: set an alarm at a deviation above 5%. Set the warning in the printer menu. Viscosity outside the nominal window is the main reason for satellite droplets.
Dry the printhead chamber after every CIP wash. Thirty seconds of filtered compressed air on the printhead before the line starts. A trivial ritual that eliminates cause number two.
05 · Frequently asked questions
FAQ
Can EHT Trip damage the printer?
The alarm itself, no — that is exactly what the protection is for. But if you ignore a recurring EHT Trip and keep printing anyway, you expose the HV power supply board to repeated current spikes, which can burn out the filter capacitors. In practice: after three EHT Trips within an hour, switch the printer off and call a service engineer.
Is this the same error as EHT Trip Bit 6 / High Voltage Off?
Yes — three names for the same event. "EHT Trip" is the main message on the operator screen, "High Voltage Off" is the wording used in older firmware, and "Bit 6" is the flag designation in the ESI/WSI communication protocol. The diagnostic procedure is identical.
Can an MMTech replacement ink cause EHT Trip?
Replacements that are chemically compatible with the original ink — that is, matched to your printer model and ink type — do not increase the risk of EHT Trip: viscosity, conductivity and surface tension are reproduced one to one. The risk arises when moving from one chemical family to another (MEK to ethanol-based, for example) without a full system flush beforehand. We cover the ink changeover procedure in a separate article.
I have EHT Trip on an older 1000-series Videojet (1210, 1510). Does this article apply?
The general logic, yes. Cleaning the electrodes and drying the chamber is identical. The differences concern spare part numbers (a different CSB generation, a different HV power supply PN) and the umbilical resistance, which on older generations is not always 44 MΩ. For a service intervention on a 1210 or 1510, contact us and we will send the exact service sheet.
