Tektronix 7623, Instruction Manual

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Maintenance— 7623/R7623 Service
8. Re-install the heat radiator/Low-Voltage Regulator
circuit board assembly.
4. Disconnect the multi-pin connectors on the Z-Axis
Amplifier board.
9. Carefully reconnect the deflection plate connectors.
After each connector is installed, lightly pull on its lead to
be sure that it will remain in its socket.
5. Remove the screw on the bottom of the high-voltagr
compartment and the two screws located at the top.
10. Check the calibration of the complete instrument.
Calibration procedure is given in Section 2.
Switch Replacement.
The pushbutton switches used in
the 7623 are not repairable and should be replaced as a unit
if defective.
Graticule-Bulb Replacement. To remove a graticule
bulb, first remove the two screws securing the CRT bezel to
the front panel. Remove the plastic light shield and
retaining spring. Now, firmly grasp the defective bulb and
pull straight out. Push the replacement bulb straight into
the socket as far as it will go. Replace the retaining spring,
light shield, and CRT bezel.
6. Guide the high-voltage compartment away from the
instrument chassis. Be careful not to damage any of the
components or the pin connectors on the High Voltage or
Z-Axis Amplifier circuit boards. Disconnect the multi pin
connectors on the High-Voltage board.
7. Using an insulated shorting strap, discharge the
exposed connections to chassis ground.
8. Remove the two power transistors and the four
screws which secure the High-Voltage board to the high
voltage compartment. Now, all of the circuitry in the
high-voltage box can be reached for maintenance or
replacement except those in the encapsulated assembly.
Power Transformer Replacement. Replace the power
transformer only with a direct replacement transformer.
When removing the transformer, tag the leads with the
corresponding terminal numbers to aid in connecting the
new transformer. After the transformer has been replaced,
check the performance of the complete instrument using
the procedure given in theCalibration section.
High-Voltage Compartment. The components located in
the high-voltage compartment can be reached for main­
tenance or replacement by using the following procedure.
Diagram 6 shows the location of the components in the
high-voltage compartment and color-coding of the wires.
NOTE
AU solder joints in the high-voltage compartment
should have smooth surfaces. Any protrusions may
cause high-voltage arcing at high altitudes.
1. Remove the heat radiator/Low-Voltage Regulator
assembly as described previously.
2. Disconnect the CRT base socket.
3. Disconnect the CRT anode plug and discharge it to
the chassis. Using an insulated probe or wire,discharge the
jack portion of the CRT anode connector to chassis ground.
9. To replace the encapsulated assembly, remove the
four screws located on the bottom of the High-Voltage
circuit board (remove board to reach screws).
10. To replace the high-voltage compartment, reverse
the above procedure. Be careful not to pinch any of the
interconnecting wires when re-attaching the high-voltage
compartment to the chassis.
Fuse Replacement. Table 4-3 gives the rating, location,
and function of the fuses used in this instrument.
TABLE 4-3
Fuse Rating
Circuit
Number
Rating Location
Function
F1000 32 A Slow
Rear panel
1 10-volt line
F1000
1.6 A Slow
Rectifier board 220 volt line
F814 2 A Fast
Rectifier board High voltage
F855
0.15 A Fast
Low-Vo I tage
Regulator board
+ 130 volts
Recalibration After Repair
After any electrical component has been replaced, the
calibration of that particular circuit should be checked, as
well as the calibration of other closely related circuits.
4-16