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Troubleshooting - DeVilbiss JGP-504 Quick Start Manual

Conventional spray gun, hvlp spray gun

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TROUBLESHOOTING

CONDITION
Heavy top or
bottom pattern
Heavy right or left
side pattern
Heavy center pattern
Split spray pattern
Jerky or fluttering spray
Unable to get round spray
Will not spray
Starved spray pattern
Excessive overspray
Excessive fog
Dry Spray
Fluid leaking from
packing nut
Fluid leaking or dripping from
front of pressure feed gun
*Most common problem.
CAUSE
Horn holes plugged.
Obstruction on top or bottom of fluid tip.
Cap and/or tip seat dirty.
Left or right side horn holes plugged.
Dirt on left or right side of fluid tip.
Remedies for the top-heavy, bottom-heavy, right-heavy and left-heavy patterns:
1) Determine if the obstruction is on the air cap or the fluid tip. Do this by making a test spray
pattern. Then, rotate the cap one-half turn and spray another pattern. If the defect is inverted,
obstruction is on the air cap. Clean the air cap as previously instructed.
2) If the defect is not inverted, it is on the fluid tip. Check for a fine burr on the edge of the fluid
tip. Remove with #600 wet or dry sand paper.
3) Check for dried paint just inside the opening. Remove paint by washing with solvent.
Fluid pressure too high for atomization
air (pressure feed).
Material flow exceeds air cap's capacity.
Spreader adjustment valve set too low.
Atomizing pressure too low.
Material too thick.
Atomization air pressure too high.
Fluid pressure too low.
Spreader adjusting valve set too high.
*Loose or damaged fluid tip/seat.
Material level too low.
Obstruction in fluid passage.
Dry or loose fluid needle packing nut.
Spreader adjustment screw not seating properly.
Air cap retaining ring loose.
No air pressure at gun.
Fluid needle adjusting screw not open enough.
Inadequate material flow.
Too much atomization air pressure.
Gun too far from work surface.
Improper stroking (arcing, gun motion too fast).
Too much, or too fast-drying thinner.
Too much atomization air pressure.
Air pressure too high.
Gun tip too far from work surface.
Gun motion too fast.
Gun out of adjustment
Packing nut loose.
Packing worn or dry.
Packing nut too tight.
Dry packing.
Fluid tip or needle worn or damaged.
Foreign matter in tip.
Fluid needle spring broken.
Wrong size needle or tip.
SB-2-291-C
CORRECTION
Clean. Ream with non-metallic point.
Clean.
Clean.
Clean. Ream with non-metallic point.
Clean.
Balance air and fluid pressure.
Increase spray pattern width with spreader
adjustment valve.
Thin or lower fluid flow.
Adjust.
Increase pressure.
Thin to proper consistency.
Reduce at transformer or gun.
Increase fluid pressure (increases gun
handling speed).
Adjust.
Tighten or replace.
Refill.
Backflush with solvent.
Lubricate or tighten.
Clean or replace.
Tighten.
Check air supply and air lines.
Open fluid needle adjusting screw.
Back fluid adjusting screw out to first thread
or increase fluid pressure at tank.
Reduce pressure.
Adjust to proper distance.
Move at moderate pace, parallel to work
surface.
Remix properly.
Reduce pressure.
Reduce air pressure.
Adjust to proper distance.
Slow down.
Adjust.
Tighten, do not bind needle.
Replace or lubricate.
Adjust
Lubricate.
Replace tip and needle with lapped sets.
Clean.
Replace.
Replace.
Page 5

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This manual is also suitable for:

Jgpv-504