Maintenance—Type 422 AC-DC
The following procedure outlines the removal and
replacement of the cathode- ray tube:
A. REMOVAL:
1. Remove the power supply and then remove the
indicator cabinet as described previously.
2. Remove the light filter or faceplate protector.
3. Disconnect the CRT anode connector. Ground this
lead and the anode connection to discharge any stored
charge.
4. Disconnect the trace-rotation leads at the Horizon
tal Amplifier board.
5. Unsolder the -12-volt power supply lead at the Y
Axis Align control.
6. Disconnect the deflection-plate connectors. Be care
ful not to bend the deflection-plate pins.
7. Remove the CRT socket shield.
8. Remove the CRT socket.
9. Remove the two nuts (by the graticule lights) which
hold the front of the CRT shield to the subpanel.
10. Remove the graticule lights from the studs and posi
tion them away from the shield.
11. Remove the remaining two screws holding the shield
bracket to the rear of the indicator.
12. Slide the CRT assembly to the rear of the instru
ment until the faceplate clears the mounting studs. Then
lift the front of the CRT assembly up and slide it out of the
instrument.
13. Loosen the CRT clamp at the rear of the CRT shield
near the shield bracket. 14
14. Hold one hand on the CRT faceplate and push for
ward on the CRT base with the other. As the CRT starts
out of the shield, grasp it firmly. When the CRT is free of
the clamp slide the shield completely off the CRT. Be
careful not to bend the neck pins.
B. REPLACEMENT:
1. Insert the CRT into the shield. Be careful not to
bend the neck pins. Seat the CRT firm ly against the shield.
2. Tighten the CRT clamp.
3. Place the light mask over the CRT faceplate.
4. Using a method similar to that for removal (step 12)
re-insert the CRT assembly into the instrument. Be sure the
CRT faceplate seats properly in the subpanel.
5. Replace the two lower screws in the shield bracket.
6. Replace the graticule lights and securing nuts.
7. Replace the CRT socket and socket shield.
8. Reconnect the anode connector. Align the plug on
the CRT and the jack in the connector and press firm ly on
the insulated cover to snap the jack into place
9. Reconnect the trace-rotation leads and the -12-volt
lead at the Y-Axis Align Control.
10. Reconnect the deflection-plate connectors. Correct
location is indicated on the CRT shield.
11. Adjust the TRACE ROTATION, Y Axis Align and
Geometry adjustments. Adjustment procedure is given in
the Calibration section. Also check the basic vertical and
horizontal gain.
NOTE
If the Trace Rotation adjustment does not have
enough range to make the trace parallel with the grat
icule lines, reverse the connection of the leads at the
Horizontal Amplifier board.
Fuse Replacement. Table 4-4 gives the rating, location
and function of the fuses used in this instrument.
TABLE 4-4
Fuse Ratings
Circuit Rating
Location Function
number
FI 000
3/4 A Fast
Rear of power supply
115-230 V line
F1014 3 A Fast
Rear of power supply
11.5-35 V line
Rotary Switches. Individual wafers or mechanical parts
of rotary switches are normally not replaceable. If a switch
is defective, replace the entire assembly. Replacement
switches can be ordered either wired or unwired; refer to
the Electrical Parts List for the applicable part numbers.
When replacing a switch, tag the leads and switch termi
nals with corresponding identification tags as the leads are
disconnected. Then, use the old switch as a guide for
installing the new one. An alternative method is to draw a
sketch of the switch layout and record the wire color at
each terminal. When soldering to the new switch be careful
that the solder does not flow beyond the rivets on the
switch terminals. Spring tension of the switch contact can
be destroyed by excessive solder.
Power Transformer Replacement. The power trans
former in this instrument is warranted for the life of the
instrument. If the power transformer becomes defective,
contact your local Tektronix Field Office or representative
for a warranty replacement (see the Warranty note in the
4-12
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