Blurring Display; Improper Card Read Operation - HP -67 Owner's Handbook Manual

Service and Maintenance 317
Blurring Display
During execution of a program, the display continuously changes and
is purposely illegible to indicate that the program is running. When the
program stops, the display is steady.
Improper Card Reader Operation
If your calculator appears to be operating properly except for the
reading or loading of program cards, check the following:
1. Make sure that the W/PRGM-RUN switch is in the correct
position for desired operation: RUN position for loading cards,
W/PRGM for recording cards.
. If the drive motor does not start when a card is inserted, make
sure the battery pack is making proper contact and has ample
charge. A recharger may be used in conjunction with a partially
charged battery in order to drive the card reader motor. If the
battery has been completely discharged, plug in the recharger
and wait 5 minutes before attempting to operate the card reader.
. If the card drive mechanism functions correctly, but your HP-67
will not read or record program cards, the trouble may be due to
dirty record/playback heads. Use the head cleaning card as
directed. Then, test the calculator using the diagnostic program
card furnished with it, following the instructions provided. If
difficulty persists your HP-67 should be taken or sent to an
authorized Hewlett-Packard Customer Service Facility.
. Cards must move freely past the record/playback heads. Hold-
ing a card back or bumping a card after the card drive
mechanism engages could cause a card to be misread.
CAUTION
Cards can be accidentally erased if subjected to strong
magnetic fields. (Magnetometers at airports are in the safe
range.)
. Check the condition of your magnetic cards. Cards that are dirty
or that have deep scratches will sometimes not read properly.
. If you are trying to operate the calculator outside the recom-
mended temperature range, you may experience problems with
the card reader. Low temperatures may cause the calculator to
register when a magnetic card is read.