PCM-2 Manual.pdf - Voss Associates

Section 14
Clock Display Board
General Description
Two of these boards are used in each PCM-2. In addition to the clock itself,
which shows count time remaining, several red LEDs prompt users to correct
their body position if any of the sensor switches are not being actuated. The two
circuit boards are identical, however a different graphic overlay is used in each
location.
The heart of this board is the two-digit numeric display chip, which is capable of
accepting serial data from the front panel board and using that information to light
the appropriate LED digit segments. Additional bits from the display's internal
shift register are brought out to a driver chip which in turn controls the red LEDs
behind the body position displays.
Clock Display Board
Configuration
Some early boards were produced with a Lite-On PIN LTM-85306 at location AI,
which also performed the functions of A3. This part has been discontinued by
Lite-On, making boards of that vintage non-repairable.
PCM-2 units shipped by Eberline after December, 1993, contain a new revised
Clock Display Board configuration. This board requires that Firmware version
PCM2FP VI. 7 or later be installed on the Front Panel Board. Dip switch S1-8
must also be set to inform the processor of the display board installed in the unit.
On older units, dip switch S1-8 was not used and may not be installed. In this
case, install Dip Switch Eberline part #SWMI5 iin the socket. Ensure that pin 1
of the socket and position 1 of the switch are aligned. Proper operation of the
Traffic Light Displays require that S1-8 be set according to the following table:
PCM2.MANI REV AI April 1995 14-1