Heathkit IO-4550 - Page 31

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10.
11.
12.
13.
14,
15.
16.
17.
18.
19.
Readjust the SWEEP LENGTH control (R255, on the
horizontal circuit board) so the trace is 10 cm long.
Turn the HOR!Z POS control counterclockwise to
move the right-hand end of the trace 1 cm to the left.
Adjust the SWEEP LENGTH control (R255, on the
horizontal circuit board) to move the right-hand end
of the trace back to the right 1 cm.
Readjust the HORIZ POS control so the left-hand
edge of the trace starts at the left-hand graticule line.
Pull out the VARIABLE — X5 switch.
Adjust the X5 CAL control (R278, on the horizontal
circuit board) and the HORIZ POS control for exactly
2 cycles in 10 centimeters as shown in Figure 19.
When you make this adjustment, place the leading
edge of the first cycle on the left-hand graticule line
and the leading edge of the second cycle on the center
graticule line.
Push in on the VARIABLE — X5 switch.
Place the Y1 INPUT switch in the GND position.
Adjust the RAMP ZERO control (R248, on the
horizontal circuit board) until the bright spot on the
left end of the trace disappears. (This is not a critical
adjustment.)
Place the INPUT switch to AC.
Refer to Figure 17 in the ‘‘IIlustration Booklet,” and
carefully readjust the X CAL control (R268, on the
horizontal circuit board) and the HORIZ POS control
for exactly 10 cycles in 10 centimeters (1 cycle per
centimeter) as shown in Figure 18. Use the leading
edge of the second and tenth cycle for this
adjustment.
Turn the TIME/CM switch to 1 uS.
Connect a 1 MHz square wave signal to the Y1 INPUT
connector.
Use a plastic alignment tool and adjust trimmer
capacitor C229 (located on the TIME/CM switch) for
1 cycle per centimeter.
Disconnect the square wave signal.
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Turn the Y1 VOLTS/CM switch to the 200mV
Position.
Turn the TIME/CM switch to the X-Y position.
Turn the TRIG switch to Y2, +.
Adjust the Y1 and Y2 POSITION controls to center
the spot on the graticule. Adjust the HORIZ POS
control so the Y1 POSITION control will move the
spot off the screen in both directions.
Set the Y1 INPUT switch to AC.
Connect the Y1 test cable inner lead to the 1V P-P
connector on the front panel. NOTE: A square wave
voltage calibrator may be used instead of the
oscilloscope 1V P-P output.