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.

two screws on the back

Let’s see what the LCD casing is hiding: two phillips screws at the bottom of the back cover hold it in place; insert a small screwdriver into the crack around the edges and ease the plastic clips holding the front fascia aside – one clip on the sides and the bottom and four on the top. Et voilà, the front fascia is released. Four more phillips screws release the control button PCB from the front fascia.

4 screws hold the LCD to the back half of the casing

Yet another four phillips screws hold the LCD module to the back casing. Remove these and the guts can now be lifted out of the case and now the monitor is free from its plastic prison. Hurrah!

the LCD free of its plastic shackles

Before proceeding I powered the monitor back up just to check I hadn’t broken anything. I hadn’t.

Time to flip the monitor over (CAREFULLY), lay it on some bubble wrap to protect the delicate LCD module, and take a

back of the LCD module

look at the brains. The labels show the LCD module is manufactured by Sharp. This is good – Sharp make some quality screens.

The circuitry is protected by a steel cage; a separate cage protects the potentially dangerous power cables feeding the backlights. Five phillips screws hold these cages in place and are easilly removed.

the brains exposed

In the center is the main controller circuit board. The LCD module is connected to the controller by three FFCs: a 30-way white one on the right and two 50-way orange ones at the top (marked in green in the picture). The front control PCB also connect to the right of the control PCB (blue circle) and is easily unplugged.

The inverter board that powers the backlight is connected to the main PCB with a 10-way connector that passes through a ferrite ring (see the orange circles). I’m not sure why the inverter board needs ten wires going to it – I assume it is for control signals to control the baclight brightness, but I could be completely wrong. This monitor has two backlights – at top and bottom – and plug into the inverter board on the left (yellow circles). This arrangment is pretty convenient – if I decide to keep the CCFL backlighting then I can move the inverter board (to help reduce any interference with the graphics tablet) simply by extending the wire between the two boards.

After unplugging all the cables (the FFCs are released by lifting up the small flap on each of the sockets and the other cables by a combination of gentle pulling and encouragement from a small flat screwdriver) two screws release the inverter board and three for the main board. The CCFL wires are routed and held neatly in place by some plastic clips covered in what looks suspiciously like masking tape, but I’m sure is in fact some high-tech adhesive material! Ripping this tape away reveals two small screws that hold the clips in place.

the LCD brains

the LCD guts

Ta dah! I have now turned my monitor into two piles of electronic parts. I’m even pretty sure I can put it all back together properly again!

Now I’m on a roll; I put the circuity into anti-static bags and set them aside out of harm’s way. Time to see how difficult it is to take apart the metal frame holding the LCD module and backlight assembly. As it turns out, not very difficult at all: eight small screws (red) and six metal tabs (blue – one is out of sight on the bottom edge) which are easily bent with a small pair of pliers. Carefully turn the whole lot right way up and remove the metal frame that holds the LCD module in place. Carefully (VERY) remove the actual LCD screen and lay it on a flat, clean surface well away from pets, children, siblings, parents – in fact away from anyone and anything. The CCFLs now slide out of the frame – treat these almost as reverently as the screen module – they are just as fragile, although somewhat more easily and cheaply replaced.

backlight assembly assembled

CCFLs

backlight assembly disassembled

As the last photo shows, the backlight gubbins is deceptively complex. The white plastic frame contains several sheets of acrylic, all of varying opacity and thicknesses: a thin white plastic sheet at the back, an 8mm block of transparent acrylic (on the top surface of which is covered by a pattern of small white dots) and then three more opaque thin plastic sheets. The good news is there seems to be plenty of room to wire up some LEDs if I decide to replace the CCFLs.

Oh bugger….

I did read Bhrazz’s opening gambit and Drew even reminded me on the Bongofish forums. Bhrazz tells us:

“Before taking things apart try the Wacom over the working screen to see if you get interference. If you then get interference after its stripped that at least implies that it can be shielded.”

Wise words indeed, and I did mean to do this, but I forgot. If you do get a lot of interference when both the tablet and monitor are complete and assembled then there isn’t much point in going any further with this monitor/tablet combination.

One of my father’s favourite phrases is “less haste, more speed”. I hate that damn phrase, I hate that my father seems to utter it when I’m already pissed because I rushed into something and screwed it up. AAARGH!!! And yet the phrase comes unbidden to my mind. Fuck it. I guess I need to put the monitor back together and see what happens – this really will test my ability to reassemble the monitor.

In the end I decided not to put the monitor back together completely, but only just enough to power it up and connect it to the computer – with plenty of insulation underneath to make sure nothing on my desk shorts the exposed circuit boards. I figured that this way, in the event of interference, I can easily disconnect the power to the inverter board to see if this helps.

testing for jitter

no jitter found!

As it turns out, I couldn’t detect any jitter, even at the edges of the tablet. This is great. I think I’m onto a winner with this monitor.

I can’t go much further with the build until I get some longer FFC extenders and couplers. Luckilly, the search has already been done for me, lots of vendors are listed here.

Join us next week for the next exciting installment.

The best thing about the monitor is it only cost $0!!! Yep, it was free – a colleague at work had it cluttering up his office and was only too glad to be rid of it because it doesn’t have a stand – other than that it is in perfect condition. I didn’t want a stand anyway.

Compaq TFT5030 front

Compaq TFT5030 back

Join me later when I take look under the hood.