Auto Line Powder or Voltage Faults: 6 Checks

When a gun on your automatic line suddenly stops powdering, or the voltage reading on the controller keeps jumping, do not swap the gun first. Run through six checkpoints in order. Field service records show that most cases trace back to air supply, the powder path or the gun cable; genuine HV module failures are far fewer.

Step 1: Read the fault code on the controller

Modern controllers run self-diagnostics and report fault codes. On a DEBELLE board, codes H08, H10, H11 and H12 all point the same way: gun cable trouble — a loose plug, a broken or worn cable, or an HV module fault.

How to confirm: power up, read the code, inspect the matching part. If the cable plug was loose, re-seat it and the code should clear. If it persists, suspect a broken cable or the HV module.

Checkpoint 1: Air supply — look at the gauge first

Air is the leading cause of “no powder”. Per the DEBELLE electrical and grounding standard, the gun needs an input pressure of 6.0 kg or more with moisture below 2 percent, and the pressure must stay steady — no repeated dips below 6 kg (about 0.6 MPa).

On-site actions:

• Read the air gauge; if it is below 6 kg, raise the pressure first.
• If the pressure keeps fluctuating, check the compressor and pipework for leaks.
• Check pipe sizing: at least 2-inch pipe to the controller for horizontal lines, 3-inch for vertical lines.

Checkpoint 2: Hopper fluidization and pickup tube

If air pressure is fine but powder still will not flow, look at the hopper. Caked, damp powder will not fluidize, so the pump cannot pick powder up; a pickup tube set too low also starves the pump and causes no-powder or spurting.

Actions: confirm the fluidizing air is on, then adjust it until the powder surface boils evenly; reset the pickup tube height; sieve or replace caked powder.

Checkpoint 3: Powder path blockage — venturi, jet nozzle, powder tube

This is the most common area on automatic lines, which run long shifts and wear faster than manual setups.

Blocked part	What you see	Confirm and fix
Jet nozzle	Venturi effect fails; no powder or sharply reduced output	Remove and clean; also check powder for caking
Powder tube	Build-up about 20 cm past the pump outlet is typical	Pull the tube and clean; replace if worn
Venturi / injector sleeve	Output keeps dropping over days	Clean or replace
Auto-gun inner powder tube	Unsteady output, powder build-up at the gun head	Fit the auto-gun inner tube; inspect every shift

Prevention: check the jet nozzle and gun head each shift, clean the pump on schedule, and store powder dry. Models with a one-touch gun purge (such as the V12 automatic gun) clear residual powder from the pump, tube and electrode at shift change.

Checkpoint 4: Voltage will not climb — HV module and cable

Powder flows but film thickness will not build, or the display does not match reality? Follow the electrostatic test procedure:

1. Voltage below set value: check wiring and contacts first, then the HV module. The displayed value maps to actual output in a fixed way — displayed value times 0.95 approximates the real kilovolts at the gun head (a display of 40 reads about 38.0 kV), with a tolerance of plus or minus 10 percent per the factory electrostatic test procedure, affected by air humidity.
2. Frequent tripping: usually poor earthing or overload protection; check the earthing system first, then lower the working voltage.

How to calibrate on site: measure at the gun head with a high-voltage electrostatic tester, take several setpoints from 5 to 100, log the measured values and check that the two series are linear. Beyond the 10 percent tolerance, recalibrate or replace the HV module.

Checkpoint 5: Workpiece earthing

Powder flows fine but will not cling? Suspect the earthing. Powder build-up on the conveyor hooks and rising contact resistance are the usual causes. Earth rods must go at least 2 metres deep, and contact points should be secured with a bolted lug.

How to confirm: measure the resistance from hook to ground with an earth tester. A value clearly higher than a fresh hook means build-up — set a cleaning cycle by output volume. Also check the hook-to-workpiece contact face; paint and oxide layers break the circuit.

Checkpoint 6: Worn parts and non-original spares

If everything above checks out, look at the parts. Service records show that non-original spares directly cause spurting, uneven output, no powder and poor adhesion; worn electrode tips and nozzles degrade the spray pattern and transfer efficiency.

Actions: replace electrode tips, nozzles, venturis and powder tubes on schedule; use original spares and match the model (for example the round or flat electrode tips and extension nozzles specified for V16).

Quick fault path

Symptom	Check first	Then check
No powder at all	Air pressure	Jet nozzle, powder tube blockage
Weak output, spurting	Fluidization, pickup tube	Worn venturi, inner tube
Voltage below set value	Cable seated, contacts	HV module (10 percent tolerance)
Film thin but powder flows	Workpiece earthing	Worn electrode tip
Frequent tripping	Earthing system	Lower working voltage

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Checklist

• Air pressure above 6 kg, no fluctuation
• Hopper fluidizing, powder boiling evenly
• Jet nozzle checked every shift, powder tube clean
• No fault codes, cable seated and undamaged
• Display vs measured voltage within 10 percent (per factory test procedure)
• Hooks free of build-up, earth rod 2 m deep or more
• Wear parts replaced on schedule with original spares

Send us your part photos, line speed and symptoms, and we will help you narrow the fault down with this logic; where useful, we run sample spraying first and let measured data decide the setup. See the contact page.