Printronix P9012 Maintenance Manual page 114

5. Perform a final position check, as follows:
a. Install paper in the tractors and close the gates.
b. Connect an oscilloscope probe to junction of the C19 lead (7) closest
NOTE: Some versions of the sensor mounting clamp (4) prevent motion of
c. Rotate the printer vertical position knob while observing the
d. Rotate vertical position knob while observing the scope for a
e. Using your fingers, rotate the sensor back and forth a few degrees on
f.
g. Repeat (c) above to ensure that the maximum level is still 150 mV or
h. Slew the paper several times with the PAPER ADV button to check
5–30
to the edge on the mechanism driver PCBA (8); this is the input to
the paper motion detector. Connect the probe's ground clip to TP6 or
the opposite lead of C19. Set the oscilloscope between 0.1 and 1 Volt
per division as required to display the entire vertical portion of the
waveform. Set the sweep speed at about 10 mSec/division.
the sensor.
oscilloscope for a maximum signal level of not less than 150 mV
peak to peak. If the amplitude is less than 150 mV, loosen the
mounting nut (2) and move the sensor toward or away from the
paper until a maximum signal level is obtained. Some high gain
sensors will provide 2 or 3 V amplitude in some cases. Tighten the
mounting nut finger tight.
minimum signal level (with a paper hole over the sensor window –
approximately 100 mV or less).
the mounting stud to obtain an even lower signal level than in (d)
above if possible.
When the lowest level is achieved, hold the sensor in position and
tighten the mounting nut.
more. Readjust if necessary.
for false paper jams. If false paper jams occur, replace the sensor and
repeat (c) through (g) above.
Alignments and Adjustments