Tektronix 502 series, Instruction Manual

Page: 23 / 114

easily bent and you must exercise care when
making these connections to avoid breaking the
pins.
CAUTION
Do not a llo w the leads from the os­
cilloscope amplifiers to touch the
chassis when the power is on. A
short circuit o f this type can damage
the am plifier circuits.
If it is desired to couple the signal directly to
the crt plates (dc coupling), it will be necessary
to supply positioning voltages from the signal
source. These voltages must also satisfy the re­
quirement of an average level of +225 volts,
mentioned previously. To dc couple the signal
to the deflection plates, remove the leads from
the crt pins and fold them back, out of the way.
Taping the ends of the wires will prevent acci­
dental shorting to the chassis. Connect the ex­
ternal signal source to the pins of the crt.
The vertical deflection factor of the crt is
approximately 13 volts per centimeter. The hori­
zontal deflection factor is approximately 17 volts
per centimeter.
FUNCTIONAL DESCRIPTION OF CONTROLS
,
INDICATORS
,
A N D CONNECTORS
TIME BASE
TRIGGERING LEVEL. Selects the voltage point
on the triggering waveform where the hori­
zontal sweep is triggered. This control also
selects automatic triggering (AUTOMATIC
position) or allow the sweep to free-run (RE­
CURRENT position).
TRIGGER SELECTOR slope. Determines whether
triggering occurs on the rising portion (+
slope) or on the falling portion (—slope) of
the triggering waveform.
TRIGGER SELECTOR. Selects the triggering sig­
nal from the upper beam, the lower beam,
the line, or from an external signal applied
at the TRIGGER INPUT connector. The con­
trol also selects either the ac or dc mode.
TIME/CM. Selects the desired horizontal sweep
speed from a choice of twenty-one sweep
rates.
SWEEP MAGNIFIER ON. Indicates that the
sweep magnifier is on.
SWEEP MAGNIFIER UNCALIBRATED. Indicates
that the horizontal sweep is uncalibrated
since the sweep rate is in excess of the
1 fisec/c m maximum calibrated sweep rate.
TRIGGER INPUT. Input connector for external
triggering signals.
HORIZONTAL DISPLAY
HORIZONTAL DISPLAY. Selects 1, 2, 5, 10, or
20 times horizontal magnification of the dis­
played waveform. Also controls horizontal
sensitivity for external inputs applied at the
EXTERNAL connector.
POSITION. Positions both the upper and lower
beams horizontally.
EXTERNAL. Input connector for external signals
which are applied to the horizontal ampli­
fier.
® OPERATING INSTRUCTIONS — TYPE 502
3 - n