Replacing the DB-9 Connector
1. Disassemble the N-20P; the connector is on the main PCB at grid location 3A.
2. Using a low-power soldering iron, unsolder the connector from the PCB and remove it.
Save all Teflon
tubing, ferrite blocks, and insulating materials for the replacement connector.
3. Install ferrite blocks between plastic lead spacer on the connector and the PCB.
4. Insulate connector pin numbers 2, 3, and 5 with Teflon tubing, and insert inside ferrite block.
5. Add insulating material between each end of ferrite block and PCB, and secure with Loctite glue.
6. Solder new connector to PCB and visually check PCB for stray drops of solder before re-assembling.
7. Switch on the N-20P and test the connector with a patient sensor.
Adjusting Printer Darkness
CAUTION
: Adjust the printer darkness setting until the lightest legible print is visible. Setting the print
darker than this could reduce printer-head life.
Although the N-20P is designed to automatically compensate for conditions that might influence the quality of the
printout, the user may want to adjust the print darkness. The normal darkness setting is set at the factory; this
setting maximizes both readability and print head life.
1. Switch on the N-20P in spot check mode. (Spot check mode is started by depressing the instrument
measure button once.)
2. Simultaneously press and hold the ADV and ON buttons for 2 seconds. If these buttons are not pressed at
the same time, two audible beeps will sound and the N-20P wither advances the paper or switches off,
depending on which button press is first sensed. If the buttons are pressed at the same time, a single audible
beep will sound, "Pr SEt" is displayed, and the printer prints one of the following 6 lines:
PRINTING LIGHTER
(10% lighter than normal darkness)
PRINTING LIGHT
(5% lighter than normal)
PRINTING NORMAL
(normal darkness)
PRINTING DARK
(5% darker than normal)
PRINTING DARKER
(10% darker than normal)
PRINTING DARKEST
(15% darker than normal)
NOTE
: The parenthetic line description is not printed, and button presses are ignored whenever the printer
is printing.
3. Press the ADV button to change the darkness setting. The printer prints a line with each button press, and
the setting increments from lighter to darkest and then wraps back to lighter.
4. Allow the N-20P to switch off (about 30 seconds). The last printer darkness setting is remembered when
the N-20P is switched back on. Test this by repeating the procedure and skipping step 3.
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