HP 82104A Owner's Handbook Manual page 52

50 Accessories, Maintenance and Service
1. Keep the contact area on the card reader plug free of obstructions.
Should the contacts become dirty, carefully blow the dirt out of the
contact area. Do not use any liquid to clean the contacts or the card
reader.
2. Store the card reader in a clean dry place. Static electricity could
damage the card reader.
3. Always turn the HP-41C off before inserting or removing any
plug-in extension. Failure to do so could damage both the calcu-
lator and the extension.
CAUTION
Do not insert your fingers or any other objects other than an
HP module or plug-in accessory into any port. To do so could
alter the Continuous Memory or could even damage the port
or the calculator. Always keep the port caps in place over any
HP-41C ports that are not in use.
Magnetic Card Maintenance. Try to keep your cards as clean and
free of oil, grease, and dirt as possible. If a read operation results in the
CHECKSUM ERROR display, the card may be dirty. Clean the card and
try the operation again. Dirty cards can only degrade the performance of
your card reader. Extremely dirty cards may be cleaned with alcohol and
a soft cloth.
Minimize the exposure of your calculator and card readerto dusty, dirty
environments by storing them in the soft carrying case when not in use.
Each card pack contains one head cleaning card.
ABRASIVE CARD FOR CLEANING RECORDING HEAD
CONSULT MANUAL FOR RECOMMENDED USE
— THIS SIDE UP —
The magnetic recording head is similar to other magnetic recording
equipment. Any collection ofdirt or other foreign matter on the head can
prevent contact between the head and the card, with consequent failure.
The head cleaning card consists of an abrasive underlayer designed to
remove such foreign matter. However, the use of the card without the
presence of a foreign substance will remove a minute amount ofthe head
itself; thus extensive use of the cleaning card can reduce the life of the
card reader. If you suspect that the head is dirty, or if you have trouble
reading or recording cards (the display shows MALFUNCTION when you
insert the card), by all means use the cleaning card; that's whatit is for.