Ulvac EGL-206M Instruction Manual page 52

Trouble symptom
3. The beam spot is not visible
in the hearth. High voltage
and beam current are
normal.
4. The beam spot
sometimes moves.
5. The beam spot moves
toward the filament with
increase of power.
6. The magnet indicator
does not light.
The X-axis deflection coil
current is normal.
7. The magnet indicator does
not light.
The X-axis focus current
does not flow.
8. The anode plate is red
heated or melts.
Possible cause
B. Short-circuit of the high voltage
lines to ground.
A. Poor adjustment of the electron
beam gun power supply.
B. Incorrect wiring of the deflection
coils.
C. Layer short or short of the X-axis
deflection coil.
A. Unstable focus current of EB power
supply.
A. High voltage drops with increase of
power.
A. The X-axis deflection coil or lead is
shorted.
A. The X-axis deflection coil or lead is
broken.
A. Incorrect dimensions of the emitter
assembly.
SECTION 7
a. Check if the filament line is shorted to ground.
b. Check if particles of evaporant are caught on the high voltage
feed-through terminals.
c. Check the high voltage cable for insulation.
a. Adjust the deflection coil current in accordance with the power
supply instruction manual.
The beam spot can be nearly centered by adjust-ing the X-axis
coil current to 1.75A and the Y-axis current to zero when the
high voltage is 10 kV.
a. Check the wiring referring to Figure 3.4.
a. Check the resistance of the X-axis coil.
The normal resistance is 2.8
a. Check the deflection coil lead for contact and insulation.
b. Failure of E/B power supply
a. The electron beam gun power supply appears defective. See
the power supply instruction manual.
b. Check the 3-phase input
a. Check if the X-axis deflection coil lead is shorted to ground.
b. Check the resistance of the X-axis deflection coil.
( 2.8 10% at 20 C )
a. Check if the X-axis deflection coil lead is disconnected at the
connection.
b. Check the resistance of the X-axis deflection coil.
a. Correct the dimensions as shown in Fig. 5.1.
Replace deformed parts.
42
Corrective action
10% at 20 C.
(See its instruction manual.)
voltage to see if phase is open.