Philips PM 3214 Anleitung Seite 66

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— Remove the instrument covers in accordance with section 3.2.2.
— Remove the INTENS, FOCUS and ILLUM knobs by pulling them off the shaft
— Remove the earthing terminal at the front
— Remove the two screws C (Fig. 3.5)
— Remove the four hexagon screws D that secure the pushbutton switches to the front panel, (Fig. 3.6)
— Remove the two screws E that hold the attenuator to the frame bar (Fig. 3.7)
— Remove the three screws F (Fig. 3,8)
— Make a note of the positions of the miniature socket connections on the amplifier board
— Remove all plugs, miniature sockets, coaxial sockets and clamping terminals from the unit and the
amplifier board
— Remove the complete front assembly from the instrument: screening covers can then be removed to gain
access to and remove parts
— Before the pushbutton switches are refitted to the front panel, it is advisable to stick the two parts of each
clamping device together by means of adhesive tape or non-hardening glue, in order to facilitate replacement,
refer to Fig. 3.9.
— When the front panel assembly is reinstalled, make sure not to interchange the connections of the Y position
controls. The connections are correct when the trace shifts upwards if the Y position control is rotated
clockwise.
3.2.7 Replacing switches
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3.2.7.1 General
— To replace the AMPL/DIV switches, first remove the front panel assembly (section 3.2.6).
— To replace the TIME/DIV switch, first remove knobs and text plate (section 3.2.51.
— If one of the push-button switches of the main and delayed trigger source selectors (A, B, EXT, MTB or
A, B, EXT, LINE) or an input coupling switch (AC/DC 0) must be replaced, it is best to remove the front
panel assembly first (section 3.2.61. The defective switch is then replaced in accordance with the procedure
described below.
— To replace one of the push-button switches of the vertical mode switch (A, ALT, CHOP, ADD, B) or the
trigger and X deflection mode switches (AC, DC, DTB, MTB, X DEFL, AC, AUTO, DC) the amplifier
board can be removed if so desired and the defective switch is then replaced as described below.
3.2.7.2 Replacing a switch of a pushbutton unit
— Straighten the 4 retaining lugs of the relevant switch as shown in Fig 3.10.
— Break the body of the relevant switch by means of a pair of pliers and remove the pieces. The soldering pins
are then accessible
— Remove the soldering pins and clean the holes in the printed-wiring board (e.g. with a suction soldering iron)
"' —Solder the new switch on to the printed-wiring board
— Bend the four retaining lugs back to their original positions
Note: The AL T switch and the AC and MTB switch on the delayed time base compartment are dummy
--• switches which can be replaced by a not self-releasing type.
3.2.8 Replacing the cathode-ray tube
—Remove the instrument covers and rear frame (section 3.2.2)
— Remove bezel and contrast plate (section 3.2.4)
— Unplug the connectors on the c.r.t. neck
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— Ease the base socket off the c.r.t.
— Slacken the brace around the c.r.t. neck
— Unplug the trace rotation coil connector on the amplifier board and pull cable and plug through the
elongated hole in the centre frame
—Withdraw the c.r.t. through the front panel until the e.h.t. connector at the side of the tube becomes
accessible
Remove the e.h.t. connector
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—Take the c.r.t. out of the instrument via the front panel; mind the wire and plug of the trace rotation coil
— Install a c.r.t. in reverse order; position the c.r.t. screen flush with the contrast plate. The torque applied to
the screw of the brace around the c.r.t. neck must be between 0,4 and 0,6 Nm.