Tektronix 114, Instruction Manual

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Maintenance and Calibration— Type 114
Fig. 4-2. Initial control settings for calibration.
Preliminary Procedure (no power applied)
1. Check the Type 114 front-p a nel controls for smooth
mechanical operation, proper indexing, and knob spacing.
Correct all defects found.
2. Remove the Type 114 from its cabinet and check for
loose hardware.
3. Check to see that the proper fuse is installed (0.3a
slo-blo for 115-volt operation, 0.15a slo-blo for 230- volt
operation).
4. Set the Type 114 front-panel controls as shown in
Fig. 4 2.
a. PERIOD ..................... 1 µS
VARIABLE ............... CAL
b. WIDTH ....................... 100 nS
VARIABLE ............... CAL
c. AMPLITUDE ............... 3 to 10 V, + polarity
VARIABLE ............... fully clockwise
d. POWER ....................... off
e. TRIGGER .................... LEADING EDGE
5. Using the VOM, check the resistances between chassis
ground and the points indicated in Table 4-1 (see Fig. 4-3).
TABLE 4-1
Circuit
Check Points
Approximate
Resistance
T281 Primary Terminals 1 thru 4 infinity
+ 25-volt supply Outer shell of C298 1.5 K
+35-volt supply C298 + terminal
2 K
Checks and Adjustments
NOTE
Control settings and test conditions for each step
are the same as for the preceding step unless
otherwise noted.
1. Adjust +25-volt supply
9
a. Set all controls as shown in Fig. 4-2
b. Install the 50 Ω termination (T e ktronix Part No 011-049)
on the Type 1A1 Channel 1 input. Connect a 50 Ω coax
cable between the Type 1 14 OUTPUT connector and the
termination.
c. Connect the Type 114 power cord to a variable line
voltage source and set the input voltage to the Type 114 at
115 volts.
d. Turn on the equipment and allow a 5 minute warm up
before proceeding
e. Slowly rotate the WIDTH VARIABLE control clock ­
wise until the WIDTH > PERIOD light is lit. Rotate the
WIDTH — VARIABLE control counterclockwise to the point
where the WIDTH > PERIOD light just extinguishes.
f. Connect the VOM negative lead to chassis ground.
Connect the positive lead to the outside shell of C298 (see
Fig. 4-4).
g. Adjust R290 (-f-25 VOLTS) until the meter reads -f-25
volts ±0.5 volt.
4-4