Charge Line Coil Replacement - Tektronix 176 Instruction Manual

7. Compare the display of the pu Ise top with Figure 3-1.
For each charge line, the outer coils control the outer peaks
of the pulse top and the coils next to the center coil control
the center of the pulse top. To adjust a coil, loosen the
Allen screws securing the coil in place with an Allen wrench
having an insulated shaft. Move the coils together or apart
as necessary to equalize the peaks in the pulse top.
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Fig. 3-1. Display of typical 176 Pulsed Collector Supply pulse top.
[ WARN;;GJ
Be particularly careful when adjusting the coils in the
75 V
or 350
V
charge lines. The voltages associated
with these circuits make them potentially hazardous.
For a 100 V pulse, the maximum peak to peak ripple for
the whole width of the pulse top should not be more than 2
V (2% of total pulse amplitude). A tool strong enough to
pry the coils will probably be necessary to adjust the 15 V
charge line coils.
8. When the coils have been adjusted for minimum
pulse-top ripple, put the chassis section and cabinet top
back in place over the 176. Do not replace the screws.
Again, be careful not to short out anything with the chassis
section.
9. Check the pulse top again. If the ripple has increased,
remove the cabinet top and chassis section. Readjust the
Maintenance-176
coils to compensate for the change in inductance of the
charge line when the chassis section and cabinet top are put
in place.
10. Disconnect the oscilloscope from the Type 576. Set
the Type 576 DISPLAY OFFSET Selector switch to VERT
X10. Position the pulse top on the Type 576 CRT with the
CENTERLINE VALUE switch. Check that the vertical
width of the spot is no more than 2 divisions. If the spot
looks like a slash, the front corner of the pulse is not rising
fast enough. In this case, readjust the coil which controls
the front corner of the pulse for a sharper front corner.
11. Reconnect the probe to the upper plate of the
Type 576 CRT. Repeat parts 4 through 10 for the other
coils which require adjustment.
12. Replace the chassis section and cabinet top and
secure them in place with their screws.
Charge Line Coil Replacement
Use the following procedure to replace a coil or coils in a
charge line.
1. Turn off the Type 576 and remove the 176 from the
Type 576. Unscrew and remove the 176 cabinet sides and
cabinet top. Also unscrew the part of the chassis which has
the device-testing jacks attached to it.
2. Unsolder the wires attached to the coil to be
removed.
3. Remove the Allen screws securing the coil in place.
Remove the coil.
4. Place the new coil on the coil bracket in approxi-
mately the same location as the old coil. Secure it in place
with the Allen screw.
5. Reselder the wires to the terminals on the new coil.
6. Retune the charge line containing the new coil, as
described in the charge line tuning procedure.
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