Changing Preprogrammed Memory Integrated Circuits
The EEPROM Memory Integrated Circuits are preprogrammed by Dewhurst/LiftStore with the software
required to drive the displays.
The EEPROM may be fitted in various locations, will be socketed, have the same number of pins and will be
labelled in a similar manner to its new replacement.
It is important to carry out the following instructions carefully to ensure that components are not damaged.
SWITCH THE POWER OFF
Since the devices are sensitive to static electricity the pins should not be touched by hand. The EEPROMS
must be inserted with correct orientation, represented by a small notch on one end of the device to match a
similar notch on the socket.
INCORRECT INSERTION WILL INSTANTLY DESTROY THE EEPROM
Use an IC extraction tool (or small screwdriver if available). Carefully insert the tool between the EEPROM
and its socket and remove the EEPROM. If using a screwdriver take care not to damage PCB tracks beneath
and around the socket.
Check that the pins on the replacement EEPROM are in line, correct as necessary. Offer the EEPROM to the
socket whilst checking orientation. Carefully align all pins along one side to the socket then align other
side.
Check all pins are properly engaged then gently push the EEPROM into the socket. Check all pins are
engaged correctly then push firmly to ensure full insertion. Finally recheck orientation and ensure all pins
are fully inserted and undamaged.
Testing the Display Unit
SWITCH THE POWER OFF
Carefully dismantle the faceplate to permit access to the display’s field wiring terminals. Ensure that all
potentially live parts are temporarily insulated from earth.
SWITCH THE POWER ON
NOTE: Never apply power directly to the SER and PAR1 socket pins as they may be damaged.
Always connect to the actual field wiring plugs or spare plugs which are easily replaceable.
Measure the applied power between a.c. - a.c. field terminals, using a digital multimeter or equal, set to an
appropriate range. Check that the measurement meets the display unit specification.
Check the data input on SER field terminals using an oscilloscope. Do not use any other method of
measurement. See below for power off checks.
Check the gongs between G1-GND and G2-GND respectfully using a digital multimeter or equal, set to an
appropriate range. Check that the arrows flash and the gong actuates when the floor number = installed
floor only. Check SW1 switch setting if necessary.
SWITCH THE POWER OFF
If no displays are present check the serial cable on SER terminals. Temporarily remove the SER field wiring
plug from the encloder on all car and landing displays. Using a low power ohmeter, check continuity of
both serial wires and earth screen between the encoder plug and each display plug. Check for short-circuits
between active wires, screen and earth at each plug. Check polarity of active wires.
If necessary remove, replace or reinstall display unit complete with field wiring. Refix all displays and
encoder plugs.
II104/0404
