(now part of Apuljack Engineering Ltd)

Chartered Electronics Engineers - the professionals in the industry


Flexi Info

The Problem

The screens of the series 5 and 5mx are very similar - a large LCD screen module connected to the motherboard by a flexible PCB. These flexi PCB's are normally extremely reliable. However the series 5 and 5mx are let down by their design and tooling holes. These holes are used to hold and position the PCB's during manufacture, however the ones on the 5 and 5mx are inappropriately placed and cause stress fractures after repeated openings of the screen!

Why Psion put their tooling holes right in the middle of the tracks is anyone's guess - the cynics among you might say that they are there to make the flexi's fail and generate some after sales revenue. could not possibly comment on this policy!

Once removed from the machine the old series 5mx flexi (series 5 is very similar) looks like this:-

It carries the signals from the motherboard to the screen assembly. The upper, 'tail' of the flexi carries the four signals (left/right and up/down position) for the touch screen. The lower thicker connections provide the power for the back light.


The series 5mx's almost always fail at the tooling hole (see later) and this results in 1 or more horizontal lines across the screen (see picture below). The number and position of the lines can usually be changed by opening and closing the screen. If the flexi fails elsewhere (as with some of the replacement flexi's) then you may get vertical lines, flashing blocks or no display at all.

There are two classic ways to diagnose for sure.

1. You find that you can get the correct display back if you almost completely close the screen and peer through the small gap between the screen and keyboard!!

2. You take all the batteries out (backup first!!) and when you reinsert them and turn on the machine beeps.

If either of these are true then the cause is almost certainly the flexi.

If you have dismantled your machine already then you will probably have decided if your flexi is damaged or not. If you want to be sure or you need to change the flexi then look at the Fitting & Opening pages for full instructions on how to dismantle and replace it! You also need to see the important note about Sharp/Hitachi screen types.

Details of the fault

Below are typical examples of the problems that occur with the flexi's:-

Typical break location on a series 5mx

Close up of the usual problem on a 5mx - the split can be VERY small!

These splits are caused by not sticking the touch screen cables down properly on a series 5

Here we can see the 'tooling hole' problem on a series 5

Please don't try to fix it like this!!! If you are lucky, it will last a week!