Tektronix 323, Instruction Manual

Page: 69 / 170

Maintenance— Type 323
The battery should be inspected every six months or every
500 operating hours, whichever occurs first. Individual cells
or the entire battery should be replaced if venting or exces­
sive corrosion has occurred. The cover plate on the power
connector side must be removed to expose one side of the
battery. Sight between the cells to check for obvious cor­
rosion or venting on the circuit board side. If a more thorough
check of the circuit board side is desired, remove the battery
in accordance with the Battery Pack Removal instructions.
Individual Cell Replacement.
When necessary, individ­
ual cells can be removed and replaced by cutting the straps
which connect the two ends of the cell to the pack, and
soldering in a new cell. See Fig. 4-11. The cell type speci­
fied in the parts list must be used. Other types may not
function properly, despite operating claims. They may prove
to be a hazard to the instrument and to personnel. Oper­
ating time and/or temperatuure performance may be de­
graded. If, in an emergency, a substitute must be made, the
cell must be able to withstand a 180 mA charge rate. The
cells should then only be used as long as is necessary to
obtain the prescribed replacements. The battery should be
charged for 24 hours at a FULL CHG rate after individual
cells are replaced.
Cathode Ray Tube (CRT) and Trace Rotation
Coil
W ARNING
High-vacuum cathode ray tubes are dangerous to
handle. To prevent personal injury from flying
glass in case o f tube breakage, wear a face mask
or safety goggles, and gloves.
Handle the CRT with extreme care. Do not strike
or scratch it. Never subject it to more than mod­
erate force or pressure when removing or installing.
Always store spare CRT’s in original protective
cartons. Save cartons to dispose o f used CRT’s.
After the Oscilloscope cover has been removed, the CRT
and CRT shield can be removed through the following pro­
cedure:
Unscrew the black nylon thumb screw from directly behind
the CRT. Then extract the black plastic spacer from between
the CRT base and the chassis.
Remove the nut and bolt from the shield mounting bracket
located near the rear of the shield.
Slide the CRT and shield back by pushing gently on the
face of the CRT.
Raise up on the CRT and shield until the slack is taken
up on the front and rear cables, and then remove the base
socket from the CRT. Do not put too much strain on the
cables while removing the base socket. Avoid bending the
CRT base pins. The CRT is free to slide out of the front of
the shield once the base socket is removed, so be careful not
to drop it.
Slide the CRT out of the front of the shield. The trace
rotation coil in the shield now is accessible. However, its
two leads (which are soldered to terminals N and P at the
main circuit board) must be unsoldered before the coil or
the shield can be removed from the assembly.
Replacement. Reverse the procedure to replace the CRT,
observing the following precautions:
Fig. 4 -1 2 . Sketch of CRT base as view ed from rear w hen installed
in oscilloscope.
The rotation coil must be installed with its narrower
opening toward the rear of the shield.
CRT pin location and orientation in the Oscilloscope is
shown in Fig. 4-12.
Do not strike the flanges (near the face of the CRT) against
the shield when inserting the CRT in the shield.
When putting the CRT and shield in place, install the
CRT shield inside the flanges on the right and left sides of
the front panel CRT opening. The top of the shield must fit
below the double flange at the top of the front casting.
(The Oscilloscope case fits between the flanges.)
Replace the shield-bracket nut and bolt before the nylon
screw, but do not tighten them until the plastic spacer and
the nylon screw have been installed and tightened. The
flanged side of the plastic spacer should face the front of
the assembly, and the nylon screw must fit in the depression
at the center of the spacer.) Use moderate torque to fasten
the nylon screw, and then tighten the shield-bracket nut and
bolt.
It is recommended that the Type 323 be recalibrated when­
ever a replacement CRT is installed.
M ain Circuit Board
Most of the circuit components can be replaced without
removing the circuit board. If access is required to the under­
side of the board, proceed as follows:
Record the color code and then unsolder the six wires
which come from under the board at the rear panel, near
the center.
Record the color code and then unsolder the two wires
which come through the board near the side panel Ground
binding post.
4-13