Ulvac EGL-206M, Instruction Manual, Page: 54 / 55

SECTION 7
44
Trouble symptom Possible cause Corrective action
D. Poor contact of the filament cable
or filament lead.
a. Check terminals to see if they are tight. If loose, retighten
them.
E. The hearth is contaminated.
Or evaporant is not sufficiently
degassed.
a. Clean the hearth.
b. Degass evaporant sufficiently.
c. Change evaporant with a high purity evaporant.
14. The evaporation rate
decreases. No change in the
input power and beam spot
size. The vacuum level is
normal.
A. Incorrect dimensions of the emitter
assembly.
a. Check the dimensions against Figure 5.1.
B. Deformation of the filament
(filament life expiring )
a. Change the filament.
15. The evaporation rate
decreases and is unstable.
Apparently there is no
change in the beam spot
size.
A. Oxidization of evaporant. a. Change evaporant.
B. Increased ripple in the high voltage
(5% p-p or more)
a. Check if oscillation occurs in the high voltage circuit of the
power supply. See its instruction manual.
b. It is likely that radio frequency noise or thyristor noise is
superimposed on the 3-phase power line of the EB gun power
supply.
Check the waveform of the input voltage on an oscilloscope.
If noise is observed, insert a line filter.
16. The beam spot size is too
large.
A. High voltage sweep a. Lower the sweep level.
B. Decreased high voltage a. Expansion in the Y-axis direction can be supressed by using a
shorter trimming piece.
C. Excessive ripple in the high voltage. a. See item 15.
D. Incorrect dimensions of the emitter
assembly
a. Check the dimensions against Figure 5.1.
17. Distorted beam spot or no
symmetrical sweep on both
right and left sides.
A. Non uniform magnetic flux
distribution.
a. Check if there is any ferromagnetic material near the unit.
b. Check if there is any device that produces a magnetic flux.