Appendix B PREVENTING PROBLEMS
TIMEWISE 798A
79
PREVENTING
PROBLEMS
Do not open the 798A. Some components within the instrument are very sensitive to a
discharge of static electricity. Just touching a component or a solder trace on the printed
circuit board can damage the instrument. Don’t fool yourself about your immunity to static
charges. Static electricity can be generated by sliding around in a chair. You can destroy the
798A with a static charge that is considerable weaker than the voltage required to produce a
spark when you touch a doorknob.
While riding in your vehicle, a static charge is generated within the entire vehicle as the tires
flex against the road. Such static charges are generally dissipated evenly throughout the
vehicle and therefore do not cause a problem with the operation of the 798A. However,
sometimes the fabric used to cover the seats produces a localized charge on your body. In
such a case, just touching the outside of the 798A can cause a problem. If you get a shock
when you touch the door frame as you exit your vehicle, you can be sure that you’re
generating a very substantial static charge. (For your information, carbon is often added to
the rubber formulation in tires to help dissipate this static charge.)
IMPORTANT!
If static is a problem in your vehicle, Timewise suggests you treat the inside of your vehicle
with a static dissipating chemical. Anti-static chemicals, often in an aerosol or pump spray
bottle, are available from stationary and computer stores. Radio Shack sells an anti-static
aerosol spray as part number 64-2330.
As a general rule with all electronic instrumentation, never plug or unplug accessories while
the unit is turned on. The 798A carries the same warning. Damage to the 798A or the
accessory may occur as voltages are randomly applied to internal components. The 798A
and its accessories are engineered with protection against such random power surges, but
following the above guideline reduces the possibility of damage.
WARNING!
WARNING!
The driver’s module display must be plugged into the 798A before
turning on the instrument. The LED displays can be damaged if the
driver’s module is plugged in after the 798A is already powered up!
TRANSDUCER
TROUBLE-
SHOOTING
When magnets for a two-piece odometer transducer are mounted on the rim of a wheel, use
caution when parking in slush or snow. A bridge of ice might form between a magnet and
transducer if the two components are next to each other when you park. It is possible that the
transducer could be pulled out of alignment when the vehicle is subsequently moved. Park
with the magnet and transducer offset to avoid this potential problem. (You can mark the
outer rim of the wheel to identify the location of the magnet.
Do not use a reduction gear assembly in the installation of an in-line transducer. Although
you can select an odometer factor that will count mileage correctly, the pulses from the
transducer may arrive so infrequently that the 798A assumes you stop between pulses. The
result is that the speedometer on the driver’s module may not function at lower speeds.
The 798A will display an erratic speedometer reading when operating from a malfunctioning
or poorly installed odometer transducer. If the speedometer momentarily flashes an unusual
value (especially when on rough terrain), it is likely that you’ve missed a pulse or received
multiple pulses from a vibrating odometer transducer. In either case, double check your
placement of the transducer and/or strengthen the mounting arrangement. Also check for a
loose wheel, worn bushings, or even worn wheel bearings.
