LCD Module Installation

Due to the discontinuation of the PLED display modules used in production P3s, any failed display will need to be replaced with an LCD module.

The data interface for an LCD module is exactly the same as for PLED, however LCD displays require a power supply for their backlight. R19 is the backlight drive resistor on the P3 mainboard, and this was not populated on production P3s.
To use an LCD display, a resistor of the correct value must be fitted to location R19 - this value will depend on the particular LCD module used. The white-on-blue modules we use need a 47 ohm resistor.
This image shows the location of the resistor:

R19 location

Note also that preset VR1 must be adjusted to give the correct LCD contrast - this control sets the brightness on a PLED module. Roughly half-past two is a good starting position for an LCD module.

LCD modules are thicker than the PLED modules, so the height of the mounting posts must be increased.
Modules supplied by Sequentix to replace failed PLEDs will include threaded spacers.
The spacers can be screwed into the mounting posts for the PLED module, and the LCD module then screwed into the spacers.

On earlier units, there was also an overlap of the PLED module board by the function key board.
In order to clear the spacers, a small amount of material will need to be filed away from the function switch board.

Details of this can be seen in the photos below.


Here the necessary material has been removed from the function key board to allow
the mounting spacer to be fitted:
(the earliest units only used the upper two mounting posts, due to an alignment error at the factory)




Once the spacers are fitted, the LCD display can be mounted to them.
Extra washers must be used as shown here, since there is very little thread depth in the spacers:




This shows the LCD module in position, overlapping the early, wider function key board:




If you have any doubts about the process, drop us a mail for further advice.