I had been following messages on the NewtonTalk list <http://www.newtontalk.net> regarding damage to the eMate display cable with only theoretical interest until my nephew presented me with exactly this fault.
The symptoms include the loss of the touch screen so the eMate no longer responds to your stylus input and/or blank lines appearing on the screen or loss of parts of the screen image. Damage to the display cable can be responsible for all of these problems and is easily visible as a puncture or deformation of the cable itself.
When I examined the hinges of the eMate (and you have to remove the motherboard to do this), I found that one leg of the inner spring (which acts as a clutch) had popped out from under the black countersunk screw that retains it and had pierced both layers of the flexible PCB that is the display cable (Fig.6). It cut four conductors which disabled the touch screen, leaving (in this case) the bitmap display intact.
|Fig.1 One spring leg has popped out from under the retaining screw and punctured the cable.
||Fig.2 A good hinge shows both spring legs of the correct length - no danger here.
My initial diagnosis was that the faulty machine (Fig.1) had one of the inner clutch springs cut too short and was therefore not properly secured by the black countersunk screw. Simon Muller has suggested a different cause, which I now believe to be the correct one, which is that as the grease ages, dries and becomes more viscous, the spring binds on its axle and is progressively pulled out from under the retaining screw, wrapping around the axle.
When I saw this I immediately checked out my own two eMates and it was clear that this was not yet happening. Fortunately, my machines have clutch springs that have long tails on all four springs and there is no possibility that they can come free as long as they remain well lubricated (Fig.2).
If, while you are moving the eMate screen, your hear a pop or click it is very likely that one of these clutch springs have come free and you should then not move the screen at all until you have investigated further or you may cause the damage described here.
It is a relatively simple matter to repair a detached clutch by dismantling, repairing and reassembling the hinge and introducing a small washer which will retain the clutches so they cannot escape. Complete articulation is restored to the screen and the clutches can never cause a problem again.
However, this is the easy part. If the cable is also damaged, well, that's a little harder...
Notes on dismantling the eMate
I will give only brief directions here as Frank Gruendel has written a very comprehensive, illustrated guide to disassembling the eMate on his pages at <http://www.pda-soft.de/>. If you are not experienced in disassembling electronic equipment, examine these first for detailed descriptions on the techniques we have developed for splitting the case safely, removing and handling the components, tool use and other operations.
Before you start, remove any card from the eMate while it's running then turn it off, unscrew the battery compartment (2 x T8) and remove the battery.
Work on a clean, soft surface that is not static-prone (like a thin cotton cushion or blanket) to protect the case. You will need a good light to work by - some of the parts are quite small and tucked away. It's better not to work on a carpeted floor or wear clothes made from wool or man-made fibres as these can be very prone to static build-up which in turn can damage electronic components.
You will need the following tools:
- A low wattage soldering iron with a fine tip, preferably earthed or a gas/battery iron.
- T8, T10 Torx and No.0 crosshead screwdrivers.
- A pry such as slender plastic letter opener or a purpose made tool that will not damage the case as you lever the catches apart.
- A wooden or plastic toothpick to extract the rubber plugs in the base and screen.
- Fine pliers or tweezers to manipulate the small objects.
- Self-gripping pliers (Mole Grips) and heavy duty pliers to reshape the clutch springs.
- A small amount of general purpose or teflon grease.
- Two steel, zinc-plated washers, 10mm diameter, hole 3.4mm, thickness 1.0mm
If you have an earthing wrist strap, plug it in to an earthed outlet and slip it on before starting a repair. Otherwise, touch an earthed surface periodically while you work.
The first thing is to decide the type of repair you are going to perform:
- If your eMate is still working fine but you want to check the hinges to prevent any future problems, then you need only remove the motherboard and not the screen. You will then be able to assess the state of the hinges and apply some grease if they look OK and add a creased washer to the hinges for safety.
- If however the eMate does have a screen problem or the screen articulation feels too stiff/loose or you notice that a hinge is close to failure, then you will have to do both and I suggest always starting with the motherboard to prevent damage to the screen switch.
Removing the Motherboard
This is the is large printed circuit board that sits in the base of the eMate.
Lay the eMate upside down on your soft surface with the handle away from you with the screen latched shut.
- Remove the four circular rubber plugs on the base of the eMate and the one in the handle with a toothpick and remove the (5 x T10) screws.
- To split the base casings, start at the handle by just gently pulling it upwards and when loosened, insert a pry at the catch near the keyboard side of the card door and use a motion outward (away from the machine) to release it. Do the same on the other side.
- Work your way down each side and the base will pop off, probably remaining hooked on at the front edge of the case. Just lift the handle to disengage it.
- Take note of the location and polarity of the two pairs of red/black wires for the backlight and the speaker and desolder them. Disconnect the display cable from its connector at the top left of the board.
- This is a good moment to gently blow the dust off all components if you have compressed air or an aerosol duster.
- Remove only the 5 silver cross-head screws with a small white symbol adjacent to them which retain the motherboard and prepare to lift it out of the casing.
- To lift out the motherboard, get the red/black wires out of the way and then gently bend the port cover assembly outwards slightly and ease up the motherboard on that side. Then lift up the back right of the motherboard and slide it slightly to the right. Push the card release button in to allow you to lift the motherboard completely away and fold it down onto the back of the keyboard area.
- Disconnect the two keyboard connectors.
- Lift the motherboard away and place it where static will not affect it and where it won't be disturbed.
- You can now see the two hinges as photographed above. Look carefully at the tails of the spring clutches and see of they are in the process of being pulled out or in fact have come out completely.
- Having removed the motherboard, retrieve the screen switch plunger, IR lens and the charge LED light pipe and put them aside then remove the card and port doors. Observe how the cable lies in the case so you can replace it correctly later.
Screen switch plunger.
- If all looks well, you can clean off any old grease that you can reach and apply some fresh grease to the springs and axle. A creased washer (described below) can be applied to the hinges to protect the cable in future.
- If the hinges are too loose or stiff then you will have to remove the screen as well to extract the hinges and refurbish them.
Removing the Screen
Having removed the motherboard (not forgetting the screen switch plunger), turn the eMate over so it's facing you, open the screen and lay it flat. Gently remove the four black rubber plugs at the corners of the screen with the toothpick and remove the screws.
- To split the screen case easily, start at the hinge edge (bottom of the screen) and insert a pry into the rectangular slot there and use a lifting motion to prise open the first catch then slide it across and do the second one towards the centre. Repeat on the other side.
- Work your way around up both sides towards the top, inserting the pry and using a motion toward the screen to open the catches. The bezel will then lift up from the bottom of the screen and unhook at the top and off.
- Disconnect the red/black backlight cable first then take out the two top screen screws and the one retaining the ribbon cable at the bottom right.
- Place a soft cloth or sheet of foam on the keyboard. You can then gently lift the LCD screen off its supporting posts and lay it down on the cloth so you can disconnect the display cable from the back of the board.
- Remove the screen to a safe place then remove the other screws on the hinge flanges taking off the grounding clip, screen foil and finally the screen rear casing. All that will be left is the base moulding and hinges with the display cable protruding from the hinge slot.
- Before taking out the hinges, unwrap the cable, noting how it's fitted and carefully pass it down through the base and lay it aside. Now you can unscrew the larger pair of bolts from the hinges and remove them. Hinges are marked with R and L to help identification.
- Disassemble the hinges, clean all the old grease and dirt off the components, fix and reassemble them as described below and fit them back into the case.
The Hinge Repair
The hinges work by creating friction between a pair of clutch springs and the axle on which they are mounted. The tails of these springs are normally retained by the central screw.
Here you can see the faulty hinge with the short spring leg (Fig.3). We are sure (from observations made by Simon Muller) that what has happened here is that the spring has been wound onto the axle and pulled out from under the central retaining screw due to excessive friction and not as result of a break because the end of the spring is well finished and the same colour as the rest of the wire. It is also possible to see where the end of the spring used to lie from the black marks in the hinge block. The dried grease is also visible.
Disassembling the hinge
- Remove the spring clip from the end of the hinge axle:
The way to do this is to find a small flat-bladed jewellers screwdriver that fits in one of the two gaps in the circlip and twist gently so it slides out of the slot. You may have to do this using both gaps alternately.
The thing to be careful of here is:
A. Be careful about it popping out and into your eye and
B. that it doesn't ping off into oblivion, never to be seen again!
I suggest wrapping the hinge in a cloth or clear plastic bag as you remove the clip, that way you are safe and the clip stays at home.
The clip is made from a material that is a little brittle so be careful not to twist or bend it excessively.
- Gripping the tails of the clutch springs with pliers, ease them down the axle, twisting it as you pull it out and slip them off the end.
- Clean all the old grease and dirt from the hinge components.
- To straighten the clutch springs:
- Clamp the curl with a pair of self-gripping pliers (Mole grips) or a metalworking vice and bend the tail out gently.
- The springs are made from a tough but brittle wire that may fail if you are rough.
- While reshaping the spring, move the fulcrum point continually towards the curl to minimise the change in diameter. Levering from the tip of the tail only will encourage a poor shape. When you have finished you should have a tail that is straight and about 7mm long.
- The repaired spring should look like the one in the middle compared to its original state on the left. The spring on the right has a small bend to the end of the wire to help prevent it being pulled out again. I achieved this by carefully tapping the end over on the edge of an anvil.
- If necessary, adjust the curl so it's circular again by compressing it.
- It may be necessary to use a round needle file on the inside edge of the curl to ensure there are no sharp edges that will damage the axle.
- You can now reassemble the hinge components applying a little grease to them as you go.
- Use a light, general purpose grease suitable for metals - this is usually available in small dispensers from electronics stores. If you can find the white grease (which is more resistant to drying out) all the better - but it's not critical.
- Teflon-based greases are also a good choice - Triflon or SuperLube are good products.
- To get the clutches back on the axle, the easiest technique is to put one on the end of the axle inside the hinge block and compress the hinge in a vice to push the spring on.
- Work the spring down the axle a short way by gripping the tail with pliers then do the same with the second spring. Reattach the clip to the end of the axle.
- You could also place a spacer like a thick nut where the axle emerges at the left of picture above to allow you to push the clutch further up the shaft.
- Adjust the positions of the two springs so that the two tails lie in the hinge block and then mount the central screw. (The creased washer is added after the hinge is mounted in the eMate).
- The finished result will look something like this:
- Prepare a washer by clamping it in the jaws of a metal vice and tapping it with a dowel so that it looks like this:
It is now ready to be installed when the hinge is back in the casing.
- Mount the central screw to trap the two tails for a friction test.
It is under the black screw that you place the creased steel washer to securely trap the clutch spring legs - there is plenty of thread to allow for this.
- To test that hinge has the right amount of friction (so that it will support the screen at any angle), clamp the hinge block in a vice, clamp a wooden pencil to the hinge flange and hang a weight of 125g a distance of 150mm from the hinge axle. Two 'C' size alkaline cells in their packing is about right for this.
- The hinge should be able to support this weight without drooping.
- If it's too loose, you will have to dismantle the hinge again and slightly tighten the clutch springs and test it again.
- When you are satisfied with the repair, add some more grease as you work the hinge back and forth.
- When mounting the washer (at the stage where both repaired hinges are installed in the case) make sure the centre screw is tightened properly and that the crease is aligned as in the photograph below.
In situ and how it works:
[In the drawing, the clutch springs are indicated in red. The two larger screws retain the hinge assembly in the eMate and the central screw (shown here) retains the spring legs].
Fixing the spring clutches is a no-brainer if your eMate is unfortunate enough to have this problem and will save the display cable being punctured. However, fixing the cable is basically very tricky because it's so fine, but it might be worth a try - there's nothing to lose.
Repairing the Cable
I proceeded to amaze myself by actually fixing the flexible PCB by scraping away the lamination with a scalpel (under a magnifier) to reveal the copper traces beneath and soldering some very fine copper wire across the gaps. There are products available for the repair of PCB's such as Silver-loaded paints but I feel these would not be suitable for use on a flexible substrate.
Here is the cable before the repair. You can see where the puncture has cut three traces.
Frankly, I believe I was fortunate because the trace separation is only 0.5mm and bridging the traces was very likely. It worked with help from the techniques described below. I also don't know how long this fix will last in such a difficult position where the cable is constantly bending but, whatever, one less eMate is lost to the world. The ideal solution would be a replacement cable combined with good hinge maintenance and the protective washer.
I used a battery powered soldering iron (Wahl Iso Tip) for this job as it can be fitted with a very fine tip and helps to control the temperature to prevent damage to the substrate. If you have access to a temperature-controlled soldering station, you could certainly use that but mine (Oryx Skylab) does not have a tip fine enough. Low temperature solder is also helpful here as it will reduce the damage to the PCB and, because it contains some Silver, has better wetting of the (less than ideal) surfaces. For the usual Tin/Lead multicore solder, temperatures below 350 Celsius are about right and around 220 Celsius for low melting Silver loaded solder.
Repair in Detail:
- Clean the cable of any grease or dirt that may have been deposited on it - use rubbing alcohol and a cotton bud if necessary.
- Carefully separate the cable where it is folded over on itself and stuck together at three points with double-sided tape.
- Lay it roughly flat but do not flatten the places that already have a crease - let them stand as they will.
- Tape the cable down flat either side of the repair with some strong masking tape.
- Start by scraping off the upper insulating layer of the cable above the break from the lighter-coloured copper side to reveal a few millimetres of the copper trace either side.
- When most of the insulation is removed, continue with a narrow strip of very fine (1200 grade) emery paper in a pair of tweezers to create a smooth, bright surface. Be careful though, the copper traces are thin and you don't want to wear through them. This process also helps to flatten the cable which makes soldering easier. For those who have such things, a rubber polishing block will give the final, finishing touch.
- To help prevent bridging adjacent tracks, use Post-It correction tape or some Post-It notes (which do not leave a residue) which can be cut into a mask to match the curve of the copper trace. Being paper it will not melt when soldering.
- Position the paper masks on either side of the trace to repair.
- You can bridge the gap with a wire or an elongated blob of solder but be careful not to bridge adjacent tracks. The wire option is perhaps the easier of the two in most cases.
- Clean the copper wire well so that it's shiny to make the best joint.
- Tin the end of the wire and the copper traces with some solder and bend the end of the wire to match the curve of the trace to be repaired. Position it across the gap and touch the iron to it to melt the solder and make the joint. Use a flat metal heatsink like a steel rule below the cable to keep the temperatures down.
- Snip off the extra wire as close to the surface as possible and then move on to the next trace, repositioning the paper masks as required.
- When all the breaks have been attended to, you need to test that is good continuity across the repairs you have made and that there are no bridges between the traces:
- To test the cable "walk" across it with two fine probes connected to an Ohm meter or multimeter or even a single battery and a bulb - this will test for both continuity and bridges.
- To do this, touch one probe to the first trace and get continuity at the other end with the other probe. Move the first probe to the second trace keeping the second in position - this tests for bridging, then move the second probe to the second trace to get continuity and so on across the whole cable.
- If all is well, you can lift the cable and prepare it for installation into the eMate. Otherwise, go back and rework the repair.
- Note that you only get a couple of chances to solder the trace as it may lift off the substrate with the repeated heating.
- To finish your repair, place a small piece of insulating tape between the two repairs so that they cannot touch through the substrate when folded back into position.
- Wrap the repair with one layer of self-amalgamating tape to protect and insulate it. You can use insulating tape as well but it wont adhere as well in the long term.
This is mostly a reverse of the disassembly process but with some detail points to observe:
When you reconnect the battery and boot the machine, remember that the clock will need to be reset and that the volume and contrast sliders will be out of position.
- Mount the left hand hinge and install the creased washer.
- Mount the right hand hinge and washer and then wrap the cable around it.
- Thread the cable in from the inside so the repair is not dragged through the slot of the case.
- Turn the eMate over and set both hinge flanges vertical and begin to attach the rear screen shell:
- Install the silver screen foil into the shell and bring it into position.
- Place the metal grounding clip on the left hinge and drive its two screws in.
- Insert the upper screw on the right hand hinge only.
- Carefully check that the articulation of the screen is smooth and firm and that the cable is not being snagged.
- Route the backlight wires through the left-hand hinge and press them into their slots.
- Slip on your earthing strap or ground yourself to discharge any static.
- Lay the screen subassembly on the keyboard with a soft material between them and attach the repaired cable in the socket on the board.
- Seat the screen onto its posts but never press anywhere but near the blue rubber grommets.
- Attach the fourth screen hinge screw that retains the cable, checking how it wraps.
- Reconnect the backlight connector and push it into its slots.
- Mount the two screws at the top of the screen with their washers.
- Don't over-tighten any screws, they only need to be nipped in.
- Check again that the cable is not snagging on anything or being pulled out of shape.
- Clip the screen bezel on by engaging the catches at the top then pressing it home around the edges. Don't put the screws back in just yet in case it needs to be opened again.
- Close the screen, latching it, and turn the eMate over to install the motherboard.
- Install the three components of the port cover and check that the port door slides either way normally.
- As with all self-tapping screws, turn them slowly anticlockwise to find the thread then turn them clockwise to seat them. Not doing this may cause the screw to become cross-threaded, weakening the plastic post.
- A touch of grease on the tip of the self-tapping screws will greatly ease replacing them and reduce strain on the plastics.
- Install the card door.
- Pop in the screen switch plunger, tinted IR lens and the clear power LED lens.
- Put the handle rubber in with the notch uppermost.
- Check that the display cable is lying correctly in the case and that both the slider knobs are over to one side.
- Holding the motherboard by its edges only, set both slider controls to match the position of the knobs so they engage as the motherboard is installed.
- Engage and lock the two keyboard connectors.
- Make sure the two pairs of red and black wires are over to the right.
- Turn the motherboard over and slide the card eject button into its slot then lower the motherboard into place past the port cover.
- Bring the display cable out from behind the motherboard but don't connect it just yet.
- The motherboard will be a little springy on the right-hand side because of the screen switch so put just one screw in at the top right (next to the two square, gold pads) so you can check that the slider knobs are properly engaged.
- Open the screen just enough to slide your hand in and verify this then close the screen again to continue the reassembly.
- Loosen the one screw holding the motherboard so it's free to move slightly and put in the rest of the screws in. Again, a touch of grease on the tips of the screws will help.
- Attach the display cable into its connector.
- Resolder the speaker and backlight wires ensuring correct polarity.
- Replace the bottom case and the battery
- When you have checked that all is well, don't forget to put the screws back in to the screen and the bottom case and replace the rubber caps.
Grateful thanks to Mimi Cipollone, Frank Gruendel, Simon Muller & Brian Mayton for their suggestions to improve this document.
If you have any experiences with this repair or suggestions to make it better, please let me know and I might incorporate them into an updated version of this guide. joel (at) inventors-emporium dot co dot uk
All images were taken hand-held and on a tripod with a Sony CyberShot DSC-F505 stills camera in macro mode under tungsten lighting at a resolution of 1600 x 1200, from which portions were cropped.
This document is provided for personal and experimental uses only. Liability cannot be accepted for any use made of this information or for any consequences to your equipment, business or life in general. If you don't agree with these terms, please don't use the information.