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5.4.2 DP7 Printhead Gap
Too large a gap causes light print and missing dots. Too small a gap causes ribbon smear.
1. Remove the cabinet lid and ribbon cartridge (See 5.5.1).
2. Turn off power.
3. Remove the ribbon shield by raising the carriage, pushing down on the shield until it snaps free from the
carriage and sliding it out to the right.
4. Insert a .013" (.32 mm) feeler gauge between the platen (printing surface) and printhead nose from the side
of the printhead and behind the slider (plastic pivoting piece in front of the printhead nose). Insure that the
feeler is flat against the platen. The .013" feeler should just fit without raising the printhead but a slight
resistance should be felt as the feeler slides below the printwires.
5. If the gap is too small, it may be due to slider wear. Replace the slider with a new one if available. Remove
the old slider by pushing it down while holding up the carriage. See drawing in paragraph 5.6.8 below.
Orient the new slider below the slider pivot pin so that the notched corners face toward the printer rear.
Push the carriage down against the slider until it snaps onto the slider pivot pin. Check that the slider pivots
freely. Check the gap with the .013” feeler. If the gap is incorrect, proceed as follows:
6. On units with serial numbers below 70091 the gap must be adjusted by repositioning the gap plate as
described for the DP6 in 5.4.1 steps 5 & 6 but with a .013” gap. Then skip to step 12 below.
On all later units, proceed as follows:
8. Loosen the rear screws fastening the platen to the document drive side plates. Do not loosen the front
platen screws that also locate the document drive roller spring cams. See drawing below.
9. Increase the gap by pushing the rear platen screwheads downwards. Decrease the gap by
raising the rear platen screwheads.
10. Check the gap with the .013’” feeler. When it is correct, tighten the platen screws.
11. Replace the
ribbon
shield by raising the carriage, sliding the shield between the carriage and the printhead until the shield slot
is centered and then gently push the carriage down until the shield snaps into place
12. Mount the ribbon and print locally (see 3.9) to check print quality. Adjust the NORMAL and CQ DARKNESS
parameters (see 5.2).
Left side of document drive (with cabinet removed)
Rear platen screw (2)
Roller spring
Roller spring cam