On the other hand, the graphics tablet can be put back together and will work good as new – seeing as this is by far the most expensive component this is a good thing.

With the monitor in pieces I disconnected the FFCs and reconnected everything using the longer FFCs and couplers I bought. Connected it all up to the computer and powered it up and something wasn’t quite right.

monitor powered up - back-light is working but nothing else

The back-light is working so the “monitor” obviously has power, so something else must be wrong – time to check all the connections. Hmm, all the connections seem fine, I reconnected them all just in case: still the same problem. Ok , I must be missing something, time for some coffee.

It took a while but I finally figured it out by disconnecting the white FFCs and reconnecting the original cables.

The 50-way FFCs are back-to-front!

When the monitor is in it’s usual configuration, the circuit board sits on the back of the panel so in the picture above I have the 50-way FFCs back to front. Time to switch them around.

FCCs reconnected the right way round and the monitor now works

So far so good, but surely I the monitor can be slimmed down even more – do I really need the metal surround which keeps the LCD panel aligned with the back-light assembly – probably not, out with the tools again!

A few minutes later I had the LCD panel, back-light diffuser and CCFL tubes held together crudely with scotch tape. Using a piece of sheet-styrene as an insulator the back-light and LCD were laid on top of the bare graphics tablet. Time to fire up Microsoft Paint and run some tests.

CRAP! the tests revealed massive amounts of jitter.

the red text is with the monitor powered up; the blue with it powered down (but everything else the same)

It took some willpower to keep going and think things through – after all, the original tests showed next to no jitter. What’s wrong with the current set-up? It finally dawned on me that perhaps the metal surrounding the LCD and back-light was providing some electro-magnetic insulation. In the original tests I used the tablet on top of the monitor and the tablet has a sheet of aluminium on the back.

My gut-feeling told me that it was the back-light causing the interference. So lets disconnect it and re-run the tests. If necessary I can always rig up some LED array as a back-light.

test set-up with the back-light removed

Unfortunately, my gut was wrong, the lack of back-light had absolutely no effect on the jitter problems. The LCD panel itself was causing the interference. This is quite a set back – time to go back to the drawing board and try to figure out how to shield the tablet from the monitor.