360 Systems DigiCart/II Plus - Manual (Page 98)

86 • Maintenance Guide DigiCart/II Plus Owner's Manual
System Reliability
Long term reliability of DigiCart/II Plus can be understood in terms of similar systems found in
computers. Three primary factors are prominent in failure analysis of such equipment: internal
operating temperature, power level of component assemblies and dirt. The lifetime of
electronic equipment increases dramatically if it is operated at lower temperatures. DigiCart/II
Plus contains a small cooling fan. It is extremely important that this fan be allowed to do its
job.
NOTE: Do not block the ventilation slots on the side or rear of the unit. Never install it in
a custom cabinet without very good air circulation to the room.
High power assemblies tend to have shorter life spans than circuits that do not generate much
heat. There is not much that can be done about this, but it is useful to know that power supplies
are likely to fail first. Providing good ventilation is key to obtaining maximum life.
Dirt adversely affects DigiCart/II Plus. It shortens the life of the removable Zip Disks by
coating the disk surface and interfering with the head's ability to read data from the disk
surface. Dirt will also shorten the life span of moving parts in DigiCart/II Plus - such as the fan
and the motor assembly of the Hard Disk Drive. 360 Systems recognizes that DigiCart/II Plus
is intended to work for many years, and that it will eventually require service. Drives are
therefore installed in a way that allows for rapid field replacement by a qualified technician.
Other Reliability Factors
Optional Hard Disk assemblies currently being supplied have MTBF (Mean Time Between
Failure) figures of 250,000 hours. Unlike earlier hard disks, current units are not "likely to
crash" within a few years. They do not, however, have a 250,000 hour lifetime, but their
service life is estimated by the manufacturer to be in excess of five years. MTBF figures are a
good forecast of eventual service life. MTBF is calculated as:
Cleaning
Your DigiCart may be cleaned periodically with glass cleaner and a soft cotton cloth. Please
note the following important cleaning tips:
•
Do not use paper tissue wipes as these may scratch the display window.
•
It is recommended that you spray cleaning solutions onto a cloth before wiping the
DigiCart. Do not spray fluids directly on the DigiCart.
•
Silicon rubber keypads may be cleaned with mild soap and water, using a soft sponge.
Be certain to wring excess solution from the sponge prior to wiping the DigiCart.
MTBF =
(Number of Units in Sample Group) X (Hours of Operation)
Number of Failures