Users Manual Model 656/636 Maintenance / Adjustments • 31
Print Head Replacement
NEVER REMOVE THE PRINT HEAD FROM THE PRINTER EXCEPT
FOR REPLACEMENT.
TURN OFF THE POWER TO THE PRINTER BEFORE STARTING ANY
ELECTRONIC COMPONENT REPLACEMENT.
NOTE: The Anti-static wrist strap (which must contact the skin and be tight) and
anti-static gloves must be worn at all times when handling a print head to avoid
damaging the print head.
1) Review the Printhead Handling Procedure Sheet packaged with each print head to
determine if any procedures have changed before beginning this procedure.
2) Remove the ink from the machine for easy print head removal.
3) Unplug the ribbon cable that runs to the print head. Unplug the cable by firmly,
but gently pulling it out.
4) Back the print head pressure screws off counterclockwise as far as possible.
5) Place your hand (with static gloves on) underneath the print line of the print head
and push up to release the locator pins on the heat sink, while pulling the print
head to the right of the machine. This will remove the print head assembly from
the mount plate. You may need to "help" the print head out by pushing on the
heat sink with your left hand.
6) Remove the two print head mount screws located on the top of the print head
with a 2.5mm ball driver.
7) Remove the old printhead carefully from the heat sink.
8) Place the new print head into the heat sink. Check to see that the new printhead
sits square in the heat sink and that there is no end play. If there is end play, or
the head does not seat properly, the heat sink guide will need adjustment.
9) Replace the two print head lock screws. Be sure that the head is resting flat on
the heat sink before tightening these screws.
10) Replace the print head assembly in the printer, making sure that the pin at the
back of the heat sink goes into the hole in the mount plate. Make sure that the
guide pins insert into both the front and back grooves.
11) Reconnect the print head cable, making sure that the connector is seated tightly.
NOTE: If the cable is not connected correctly, the print head will be destroyed when
the machine is powered on. Check to see that the cable is tight by observing
from underneath the print head. The ribbon cable connector should be inside of
the black connector located on the print head.
12) Replace the ink and double check your work. Power the machine on and make
sure that no adverse effects are noted. As a final test of the print head installation,
run a test pattern to check the print quality. You should observe an even grid of
chevrons. If you do not see such a grid, you may wish to reference the topic of
print head tangent adjustment.