Power Supply; Vacuum And Pressure Pumps - PRESTON PRESSURE PS-500 User And Maintenance Manual

 Power Supply
The PS-500 power supply consists of an external transformer with an output of 12 volts
DC. This supply is plugged into the round connector on the front of the tester. The
transformer charges the 12-volt gel-cell lead acid battery that is internal to the PS-500.
The battery enables the test box to be used in a portable fashion without a need for
external power while the tester is in operation. The test box can be used while charging, if
so desired, and may be mounted in any position or angle.
A battery monitoring circuit is also incorporated. The display will flash a "Low Battery"
warning when the battery voltage is near 9 volts.
The useable charge duration of the battery will vary, depending on how long the vacuum
and pressure pumps are left on. In order to obtain maximum charge durability, as well
as extend pump and battery life, it is recommended that the pumps be left on only
for the amount of time needed to charge their respective reservoirs, as shown in the
gauges. Then the pumps should be cycled on and off as needed. When used properly,
the user should be able to obtain several hours of operation directly from the battery
before needing to re-charge. In factory tests, with a fully charged battery, the battery
lasted for over 8 hours when powering only the displays.
Vacuum and Pressure pumps should not be
allowed to run continuously. Toggle the
switches as needed to re-charge the reservoirs
as seen on the vacuum and pressure gauges.
 Vacuum and Pressure Pumps
The vacuum side uses two pumps, connected in series to achieve a vacuum level required
for high altitude tests. The pressure side uses one pump, which is sufficient to reach all
the pressures necessary for normal pressure tests.
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