NCR 7156, Руководство по эксплуатации и устранению неисправностей

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12 Chapter 2: Troubleshooting
Degraded Buck Coil Connections
Set the printer for the MICR adjustment and print out a few readings.
For more information, see “In-Place MICR Adjustment” on page 20.
Work the buck coil connections by reaching in to the harness terminals
with needle-nose pliers and working each wire back and forth about
an eighth of an inch. The wires and connectors are shown in the
illustration above. Close the cover, if open, and print out a few more
readings without touching the MICR adjustment pots. If the results
differ from the previous readings by more than two letters, replace the
buck coil and its harness. Cleaning the contacts in addition to this
connection agitation exercise may restore proper operation as a
temporary measure.
Faulty Amplifier, Read head, or Buck Coil
Unplug the read head and the buck coil from the PC board.
Reassemble the printer and run the MICR read test.
•
If the test result is “NO MICR CHARACTERS,” either the read
head or the buck coil is faulty. Check the following resistance
measurements:
•
Read head, line-to-line: 460 plus or minus 50 Ohms.
•
Buck coil, line-to-line: 5 plus or minus 1 Ohms.