Diagraph PA/4000, Service Manual, Page: 185 / 213

Technician’s Guide 2-47
The label edge sensor is designed so that it rarely needs adjustment. However, if
components in this circuit are ever replaced, you may need to follow the initial sensor
set-up procedure.
1. Locate the sensor assembly. It is a pair of long narrow metal guides with circuit
boards within it. It is connected to the front panel board by a cable and is on a
shaft that goes through the center plate of the PA/4000 just below the printhead.
2. With label stock loaded in the PA/4000, remove some labels from the backing and
position the backing material in between the "fingers" of the sensor board.
3. Connect a voltmeter to the circuit as follows: black lead to the heat sink and red
lead to TP1, located in the upper left-hand corner of the control board.
4. Adjust potentiometer R43 (this is the lower one), located on the application board
for a reading of .25 volts DC (±10%).
5. Press the FEED button on the front panel of the Prodigy Plus. After feeding
several labels for an automatic self-alignment procedure, the PA/4000 should
advance one label at a time. The voltage at TP1 should go above 2 volts DC.
2.4.4 DARKNESS ADJUSTMENT
You can adjust the Darkness value using the Hand-Held Terminal. Pressing the arrow
up key increases the burn time of the printhead, thus producing a darker image on the
label. Pressing the arrow down key decreases the burn time of the printhead thus
lightening the image on the label.
This adjustment should be used after printhead replacement to supplement the
difference in printhead characteristics. Do not adjust the Darkness to make up for other
PA/4000 adjustments, this could lead to print quality problems in the future.
2.4.5 ADJUSTING THE AIR ASSIST TUBE
1. Turn the PA/4000’s power switch to the OFF position.
2. Loosen the Air Assist tube mounting bolts using a 9/64 Allen wrench.
3. Rotate the Air Assist tube to a position where the air holes blow directly onto the
Tamp Pad.
4. Test by Feeding labels until the label lays correctly on the pad.
2.4.6 ADJUSTING THE AUTO-RETRACT SENSOR
1. Locate the Auto-Retract Sensor on the Tamp Pad.
2. Loosen the screw holding the sensor to the pad using a flat head screwdriver.
3. Move the Auto-Retract sensor down to see the product sooner - retract sooner - Too hard.