Tektronix 2445, Инструкция по эксплуатации

Страница: 166 / 351

Maintenance— 2445 Service
1. Remove the instrument Cabinet as described in that
procedure.
2. Remove the front-panel trim and outer crt bezel as
described in the Front-Panel and Variable board assembly
removal instructions.
3. Remove the eight screws holding the crt mounting be­
zel in place and remove the bezel and plastic gasket. Note
the length difference in the screws for reinstallation.
4. Remove the plastic lens from the Scale-Illumination
board.
5. Disconnect the scale-illumination multipin connector
from the Main board (PI 81).
6. Remove the Scale-Illumination board by lifting it away
from the front frame while working the wires and connector
through the slot in the frame.
To reinstall the Scale-Illumination board, perform the re­
verse of the preceding instructions.
CRT Removal
Use care when handling a crt. B reakage o f the crt
m ay cause high-velocity scattering o f glass fragm ents
(im plosion). P rotective clothing an d s a fety glasses
(preferably a full-face shield) should be worn. A void
striking the c rt on an y object which m ay cause it to
crack o r im plode. When storing a crt, p lace it in a p ro ­
tective carton o r s e t it face dow n on a sm ooth surface
in a p ro tected location. When sto red face dow n, it
should be p laced on a soft, nonabrasive surface to
p reven t the c rt face p la te from being scratched.
1. Remove the instrument Cabinet as described in that
procedure.
2. Remove the Top-Cover Plate as described in that
procedure.
3. Loosen the two screws on the left side of the crt sock­
et cover and remove the one on the right side. Remove the
cover.
4. Unplug the crt socket by gently prying the socket
evenly on both sides until the pins can be disengaged. Do
not apply excessive side pressure on the socket as it is
being removed.
W A R M I N G
I
The c rt anode lead an d the o utpu t term inal o f the
H igh-V oltage M u ltip lier can retain a high-voltage
charge a fte r the instrum ent is turned off. To avoid
electrical shock, g round both the c rt anode le a d an d
the high-voltage le a d to the m ain instrum ent chassis.
R e p e a t the grounding process several tim es to fully
dissipate the charge.
5. Disconnect the crt anode lead connector and dis­
charge it to chassis ground.
6. Using long-nosed pliers, disconnect the horizontal and
vertical deflection leads from the bottom of the crt. Pull
straight out on these connectors to prevent excessive strain
on the metal-to-glass seal. (Access to the connectors is
through holes in the Main board).
7. Using long-nosed pliers, disconnect the vertical termi­
nation leads from the top of the crt.
8. Using long-nosed pliers, disconnect the crt shield re­
sistor from the top of the crt.
9. Disconnect the Y-Axis Alignment coil connector from
the front of the High-Voltage board (P903).
10. Remove the front-panel trim ring and outer crt bezel
as described in the Front-Panel and Variable board assem­
bly removal instructions.
11. Remove the eight retaining screws from the crt-
mounting bezel at the front of the crt. Note the difference in
length of the screws for reinstallation.
12. Remove the crt mounting bezel and plastic gasket
from the crt.
6-29