Atec Tektronix-1502 - Manual (Page 38)

TM 9-4935-601-14-3&P
Q5226 will conduct only when the Strip Chart Recorder is plugged in. Q5237 and Q5229 act as a dc level
shift amplifier between flip-flop U5127B and the Slow Ramp Generator, which is on the Vertical board.
Chart Recorder Power Switch. The plus or minus 8 volts to drive the stylus movement is applied to the
Strip Chart Recorder through two electronic switches, Q5273 and Q5277. Q5179 parallels Q5273 to provide
more current in the +8 V line, These switches are driven by the same signal that is used to control stylus heat
switch Q5239. This signal is passed through Q5173 and. Q5279 to the switches.
Anti-Bounce Record. This circuit, consisting of U5156A and Q5156D, removes switching transients from
the RECORD switch. The output of this circuit goes to the Vertical board to control the X-Y Record Logic. The
Record Logic in turn provides the logic control signal that is received through pin 2 of P53 on the Logic board.
If the Logic board is removed from the TDR unit, the harmonica connector from the RECORD switch should be
connected to P28 on the Vertical board.
X-Y Output Module (Schematic 7)
The X-Y Output Module provides an electrical interface between the 1502 and an external X-Y Chart
Recorder. Three signals, PEN LIFT, X Output, and Y Output are provided for use by the external Chart
Recorder. The switching mechanisms for the outputs are solid state devices, therefore care should be taken
when connecting loads to them. See the specification listed in the Specification section of this manual.
Pen Lift. The Pen Lift signal level changes when the RECORD switch is activated. The normal level is
either 0.0 V ±0.5 V or 5 V +0 or -1 V, depending on how the terminal link of the X-Y Output Module board is
connected (positive or negative slope, see Fig. 3-8). When the RECORD switch is activated, the level will
change from 0 V to 5 V or from 5 V to 0 V. The driving capability of this signal source is given in the
Specification section of this manual.
Figure 3-8. X-Y Output Module Strap.
Diode CR7247 is used to clamp the negative voltage swing to -0.6 V. Q7242 provides the capabilities for
the operation of units with a positive pen lift or a ground return path.
X Output. The X output is directly proportional to the horizontal position of the crt beam along the crt face.
This signal is a ramp of approximately 20 seconds duration and raises at a rate of 0.1 V for each division of
horizontal travel across the crt. This 0.1 V per division scale factor is set by a voltage divider network
comprised of R7138, R7129 and R7122. C7132 is used to reduce noise. Source impedance is less than 13 K
(9.4 K minimum).
Y Output. The Y output is directly proportional to the vertical deflection on the crt. The scale factor (volts
output per division of crt deflection) is adjustable, from 0.09 V per division to 0.13 V per division (factory set for
0.1 V/div), by variable resistor R7225. The source impedance of this signal is less than 11 k
Ω
(8 k
Ω
minimum)
and is determined by R7234, R7224 and R7225. C7232 is used to reduce noise.
REV A FEB 1980
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