Tektronix 1A1, Инструкция по эксплуатации, Страница: 8 / 137

SECTION 2
OPERATING INSTRUCTIONS
Type 1A1
Change information, if any, affecting this section will be found at the
rear of the manual.
FUNCTIONS OF FRONT PANEL
CONTROLS AND CONNECTORS
The functions of all front-panel controls, adjustments and
connectors except the MODE switch, CH 1 SIGNAL OUT
and CH 1 TRIGGER OUT connectors are identical for both
channels.
POSITION
PULL FOR
INVERT
VARIABLE
VOLTS/CM
Positions the trace vertically on the CRT.
Two-position switch that presents the in­
put signal in either normal or inverted
polarity.
Provides overlapping variable uncalibrat­
ed attenuation between the calibrated de­
flection factors and extends the attenua­
tion range to about 50V/cm. The con­
trol activates a switch when moved out
of the CALIB (calibrated) position to pro­
vide the overlapping coverage.
.05V/CM GAIN Screwdriver adjustment that sets the basic
deflection factor of the channel at 0.05
V/cm.
.005V/CM VAR Screwdriver adjustment for setting the am-
ATTEN BAL plifier DC levels so the trace does not
shift position under no-signal conditions as
the
VARIABLE VOLTS/CM control is
turned.
VOLTS/CM Twelve-position switch to select the cali­
brated vertical-deflection factors.
INPUT
SELECTOR
Channel 1 and
2 INPUT
Connector
Three-position switch to provide either
AC- or DC-coupled input into the ampli­
fier. A third position (GND) connects the
amplifier input to ground without ground­
ing the input signal.
Signal input connector for the channel.
MODE Five-position switch that sets the mode of
operation as follows:
CH 1— Allows the use of Channel 1 only.
ALT— Dual-trace alternate mode of oper­
ation (triggered electronic switching be­
tween channels during the retrace inter­
val).
CHOP— Dual-trace chopped mode of op­
eration (free-running electronic switching
of channels at about a 1-MHz rate).
ADD— Permits adding the outputs of the
two channels algebraically.
CH 2— Permits the use of Channel 2 only.
CH 1 SIGNAL Output signal from Channel 1. Permits
OUT patching the amplified Channel 1 signal
into Channel 2.
CH 1 TRIGGER Trigger signal from Channel 1. Permits the
OUT use of Channel 1 as an external trigger
source.
CAUTION
If the Type 1A1 is inserted in the upper-beam ver­
tical plug-in compartment o f a m odified Type 555
Oscilloscope SN 101 to 6999 or in a Type 555
SN 7000 and up when the Type 21 and 22 Time-
Base units are used instead o f the Types 21A and
22A, + 8 7 V from pin 19 in the Time-Base units
is applied to pin 5 o f the Type 1A1 interconnect­
ing plug (see Fig. 2 -1 ). This voltage w ill damage
components in the Type 1A 1 Trigger Am plifier
circuit and cause the circuit to be inoperative.
In addition, the + 8 7 V is a hazard because it is
also applied to the SIGNAL OUTPUT connector.
For proper Type
1A1 operation, remove the
+ 8 7 V by disconnecting the w hite-gray wire that
goes from pin 19 in the Types 21 and 22 to the
ceramic term inal notch above V I 52.
(The Types 21A and 22A Time-Base units are com­
patible with the Type 1A1 and therefore do not
require m odification.)
FIRST-TIME OPERATION
The following procedure will help you become familiar
with the Type 1A1 operation.
1. Insert the Type 1A1 into the oscilloscope, tighten the
securing rod, and turn the oscilloscope power on.
2. Allow about 2 to 3 minutes warm-up time and free
run the oscilloscope sweep at 0.5ms/cm.
3. Set the applicable Type 1A1 front-panel controls for
both channels as follows:
INPUT SELECTOR DC
VOLTS/CM .05
VARIABLE VOLTS/CM CALIB
PULL FOR INVERT IN (normal)
POSITION Centered
MODE CH 1
4. Position the trace about 1 cm above the graticule cen­
terline with the Channel 1 POSITION control.
2-1