IBM 6400 series Maintenance Manual page 139

Shuttle Only This test runs only the shuttle.
Shuttle Slow Verifies proper operation by exercising the shuttle and
ribbon mechanisms at low speed. You can also use this test to check
ribbon tracking and reversing.
Shuttle Fast Verifies proper operation by exercising the shuttle and
ribbon mechanisms at high speed. You can also use this test to check
ribbon tracking and reversing.
Hammer Phasing A hammer timing parameter that permits you to
adjust the vertical alignment of dots in character printing.
End of Forms Adjust A vertical comb pattern used to determine the
number of dot rows from the completion of a paper out fault to the end of
the paper.
Hammer Phase Value:
The hammer phase value is a timing parameter that permits you to adjust the
vertical alignment of dots in character printing. The numerical units are
relative; they do not represent a physical measurement or value. There is no
"correct" value or range.
The factory prints the initial phase value on the aluminum casting of the
shuttle assembly, next to the motor housing. Use this value as your starting
point when adjusting hammer phasing.
End of Forms Adjustment Value:
This parameter determines where on the paper the printer will stop printing
when an out of paper fault is detected. The unit of measurement is dot rows.
The number of dot rows may be adjusted up or down 1/2 inch from the
factory default of 40 dots.
Clear Error Log:
This menu selection enables you to delete the stored contents of the error
log. The error log automatically records certain unit check conditions in a
buffer in NVRAM that stores up to 50 messages. The most recent message
is stored at the top of the list, the oldest message at the bottom of the list. If
more than 50 messages occur before the log is cleared, the oldest messages
are deleted, so that the log never contains more than 50 messages.
Troubleshooting
Power Supply board
Hammer bank cover
Hammer springs
Hammer coils (the shuttle frame assembly)
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