Hitachi NR 90AE Technical Data And Service Manual page 19

Problem
3) Head of a nail
Adjuster is improperly
driven into a adjusted.
workpiece
protrudes
Air pressure is too low.
from the wood
Workpiece is very hard.
surface.
Driver blade is worn.
Piston O-ring is abnormal
(worn or damaged).
Cylinder's internal surface is
abnormal (worn or rough).
4) Nails clog the Unspecified nails used.
mechanism.
< Improper nail feed >
See <Magazine> in item 1).
Driver blade worn.
Nail feeder (A) is abnormal
(worn or damaged).
< The driver blade has not
returned completely. >
See <Output section> in
item 1).
O-ring in plunger is worn.
5) Single
actuation
mechanism is
O-ring in valve piston is
not possible.
worn.
Abnormal plunger sliding
surface of valve piston
(seized or deformed).
Abnormal plunger, trigger
arm (C), pushing lever (C)
and/or body (worn or
damaged).
The position of a switching
device is mistaken.
Possible cause
Inspection method
Turn the adjuster to the
lowest position and drive a
nail.
Drive a nail into soft wood
workpiece and check if the
head protrudes from the
wood surface.
Operate the nailer without
nails and check if the driver
blade is projected from the
nose tip.
Disassemble the output
section and check the
piston O-ring and the inner/
outer surfaces of the
cylinder for abnormal
condition.
Check if the nails are
specified ones.
Check if they move
smoothly after putting nails,
and check if the nail feeder
operates smoothly.
Check if the driver blade tip
is worn.
Check nail feeder (A) for
abnormal condition.
Perform idle driving or
actually drive with nails, and
check if the driver blade has
returned completely.
Disassemble the control
valve section, and check the
O-ring of the plunger and
the valve piston.
Check each part for
abnormalities (worn,
damaged, deformed, etc.).
The position of a switching
device is checked.
--- 16 ---
Remedy
Adjust the adjuster to the
proper position.
Adjust for 5 to 8.5 kgf/cm
Do not use unspecified
workpieces.
Replace the driver blade.
Replace the defective part.
Use specified nails.
See <Magazine> in item 1).
Replace the part.
Replace nail feeder (A).
See <Output section> in
item 1).
Replace the part.
Replace the part.
Replace the part.
Replace the abnormal part.
A switching device is set to
the correct position.
2 .