GDP-32
II
DESIGN
Section 16, Page 23 May 2002
16.7 THE BATTERY COMPARTMENT
SMALL CASE DESIGN (GDP-32
II
T)
The battery compartment is accessed from the top of the case by removing the front
panel. This compartment contains two 6 volt, 10 amp-hour batteries connected in series
to provide 12 volts with 10 amp-hours capacity.
To service the battery compartment, remove the front panel assembly and the 4 #6-32
phillips head machine screws that secure the compartment lid to the battery case.
LARGE CASE DESIGN
The battery compartment in the large case GDP-32
II
connects to the bottom of the
receiver case by locking clips. There are four 6 volt batteries, wired in series and parallel
to provide a 12 volts with 20 amp-hours capacity.
The Lower Case Panel is removable to permit access to the bottom of the Main Case.
There is a 4 amp inline fuse protecting the main 12 v supply. Spare fuses are placed
inside the lower case panel in all new GDP-32
II
s.
Read Section 17.5 before attempting to remove batteries for the large case directly.
NOTE: If one battery goes bad, it is often advisable to replace the complete battery
package with new batteries, rather than to replace batteries individually.
A rubber gasket provides a weatherproof seal. Electrical connection is provided through
one of two three-wire connectors mounted on the lower case panel. The batteries can be
plugged into either connector. The second connector is used to plug in a replacement
battery pack before unplugging the battery pack in use, so that power to the timing
circuits is not interrupted.
Battery voltage is checked before each data acquisition cycle. It is displayed at the top of
the LCD screen. When battery voltage drops below 11.2 volts, a warning message
appears, and the operator has 10 to 20 minutes before the circuit breaker disconnects.
Both small and large case models of the GDP-32
II
contain an electronic circuit breaker
located on the front panel board (BD287) that disconnects power when the battery
voltage drops below 10.6 volts or rises higher than 15.5 volts.
See Section 17.5 for information on checking and replacing batteries.
16.8 THE CRYSTAL OSCILLATOR
All GDP-32
II
timing is based on a precision oven-stabilized 4.980736 MHz quartz
Crystal Oscillator (see footnote on page 16.19). The Crystal Oscillator is mounted
directly to the calibration and timing board on the large case GDP-32
II
. On the small case
GDP-32
II
T, it is mounted next to or on top of the battery compartment.
The high accuracy crystal has provisions for both electrical and mechanical trim.
Electrical adjustment of the crystal is explained in Section 6.2 and mechanical adjustment
is described in Section 17.6.
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