NCR 7156, Руководство по эксплуатации и устранению неисправностей

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4 Chapter 1: 7156 MICR Operation
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For any MICR document, check for “?” character misreads, and
serious misread problems such as “NO MICR CHARACTERS”,
substantially garbled translation, or character substitutions.
Necessary Conditions for MICR Reading
The following section outlines the conditions that affect MICR. Make
sure that your printer has been set up and operates within the
following guidelines.
Electrical grounding and bonding: The major metal structures within
the printer must be securely bonded together and connected properly
to the host system ground. If they are not, electrical noise may enter
the MICR amplifier and distort the signals. This electrical noise can
cause misreads.
Correct MICR adjustment: The motor that feeds documents in and
out of the printer for MICR reading emits magnetic pulses. If the MICR
is not adjusted properly, the magnetic pulses from the motor may
interfere with the weak magnetic signals from the MICR characters.
This electrical interference can cause misreads. During the adjustment,
the front cover must be closed; there must be a blank document over
the read head and behind the feed rolls; and the print head carriage
must be in the exact location provided by the printer after a reset.
Read head contact and movement:
The MICR read head and the
surface of the document being read must remain in continuous contact
during the reading phase. Reading accuracy will degrade if the
alignment of the read head with the MICR characters (in skew and in
both axes of tilt) is not correct.
Document Motion: Reading accuracy will degrade if the document
does not move smoothly and at a uniform velocity out of the printer.
Undamaged, in-spec MICR documents:
The documents must meet the
requirements for the printer and contain no folds, creases, or random
magnetic particles in the MICR character region.