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How to take your NEC Mobilepro 7X0 apart and put it back together again - by Rich Hawley Many of the mechanical parts from the 770 and 780 and 790 are interchangeable, such as the lcd assembly, case, keyboard, etc. The LCD units are swappable between all three units. The backlight daughter boards are swappable between the 770 and 780, but not between the 770/780 and 790. There are a few 790s with first generation motherboards that will support 770/780 backlight board, but not all do, so it is best to not get into this issue. Nor is the RAM swappable between the 770 and the 780/790. You can add the 780 RAM to the 790 to increase the useable memory to 48mb. The 770 system ROM chips are not swappable with the 780/790. You can use the 790 ROMs in 780 machine, but you will lose the 16mb of flash ROM in doing so. Still this allows you to turn your 780 into a hybrid Wndows CE 3.0 machine, which many have renamed the Mobilepro 789. Finally, only the 780 and 790 have the scroll wheel, but this does not need to be present or connected for the 780 or 790 to operate properly. The AA battery pack is the same for all units, but the normal LION batteries are different. The 790 has a higher capacity battery, and it is designed so that it will not fit into a 770/780. The 770/780 batteries do however fit into a 790 and will operate with less capacity. The following is an unofficial file that I have created that demonstrates how to disassemble a NEC Mobilepro 770/780/790 series handheld for repair of the unit by parts substitution. There may be better instructions, but I haven't found them out there on the internet. Disclaimer: You do this at your own risk. Optimally you would perform this using proper tools such as an antistatic mat, grounding straps...you know, all the electronic safety tools that electronic technicians use. Since I don't have access to all of that, I will just use a precision screwdriver set and sit at my desk. Pre-disassembly steps Back up all of your data. I know this seems silly, but you would be surprised at all the people who complained about losing their data when they took their units apart. Like it was my fault that I didn't warn them...well now I have. Disassembly Step 1 - Remove the battery Step 2 - Remove the two tiny little screws that are normally hidden underneath the battery. See Picture 2 for location.  Step 3 - Turn unit over. Remove 8 screws as shown in Picture 3. The screws are of three different sizes. The main case screws are the longest, there is a single medium length screw that comes out of the center, and two very short machine thread short screws that attach to the hinge of the lid.
 Step 4 - Remove the rom cover plate by unscrewing the one screw (Picture 4). You don't have to unscrew it all the way, just until you can slide/move the plate/cover freely. At this point I always remove the two small daughterboards. One is the ROM chip and the other is the RAM chip. You do not have to remove them, but I do just to prevent possible injury to them.
 Step 5 - The distant daughterboard in Picture 5 pops out easily when you spread the holders apart. The other chip unscrews with two little machine thread screws, and they are brass colored, not like the ones you took out earlier. Remove that chip too. Note that for a 780, both of the daughterboards screw into place, not just the one towards the front like the 770.
 Step 6 - Now remove the two ribbons from their connector by sliding the locking mechanism towards you (Picture 6). My arrows point to the ends of the locking bar that you slide towards you. This will make the ribbons sit loose in the connector, you can now slide the ribbon out from the connector using one of your trusty small screwdrivers behind the ribbon and pulling it carefully out of the connector as I show in the picture to the left.
 Step 7 - At this point, I stand the unit on end with the unit partially open. I like to start on the same end every time.
 Step 8 - I always start near the modem connector. Carefully pry the bottom case cover from the keyboard insert. These two parts simply snap together with the gray part residing inside the silver part. There are little plastic catches spaced along the edge that help hold the two parts together. Note the angle of my screwdriver. I am pressing downwards while applying mild pressure to separate the two halves. Work in very small steps, about 1/2-3/4 of an inch apart and you will find they separate fairly easily. DON'T LET THEM GET TOO FAR APART! There are fragile wires connecting the keyboard to the motherboard within, so don't pull them too far apart or you might damage the LCD ribbon cable. You do have some laxity to spare (an inch or so), so don't panic…just do it slowly and carefully and you'll be all right. I prefer to loosen the ends first, and then work along the front edge where the spacebar is. Work yourself completely around the unit until you can feel/see that the two halves have separated.
 Step 9 - Now from the front of the unit, if you carefully lift the lid you will see the ribbon (Picture 9) that connects the lcd lid/unit to the motherboard and bottom half. Carefully loosen the ribbon locking bar and remove the ribbon cable from the motherboard. You should now be able to separate the lid/keyboard from the bottom case/motherboard.
 Step 10 - NEC 780/790 only. There is also a connector you need to disconnect for the thumbwheel on the main motherboard. It's pretty simple to unplug, but it may be taped to the bottom side of the keyboard, so be careful that you don't tear it off.
 Step 11 - There are two loose pieces that may fall out, don't worry about them (Picture 11). One is for the slide lock for the battery. It pushes against a micro switch on the motherboard and this is why you can't turn on your Mobilepro when the battery is not locked into place. The other is a small clear plastic piece that is lit by the charging leds. This simply slides into the bottom case to the right of the microphone. Go ahead, try and see if you can fit these two pieces back into place now so you will be familiar with how they fit. When you are done, set them aside.
 The keyboard is really two separate parts. The core is the unit that fits within the frame of the bottom half. There may be a time when you want to separate the two, say you have a broken hinge cover but the keyboard core is still intact. The keyboard is held into place with double backed tape and by two small plastic tabs at the bottom. To remove the keyboard, gently separate the core from the frame along the top. When you are able to lift it up from the frame, the rest of the unit will separate easily. Just don't pry along the bottom as that is where the plastic tabs are and can be broken easily. Here is a couple of pics showing how it is held together:
 This is the underside of the keyboard, flipped over...note the ribbon cables for reference.
 Step 12 - Looking now at the bottom half you should see (Picture 12) that there are 5 screws that hold the motherboard in the bottom case. Note the microphone, the speaker, the backup battery location, and a lip of the motherboard where it is held in place by the case design. To change the backup battery out, first disconnect the speaker, remove the microphone from its area (it is only pressure fit into a little slot), and carefully lift up on the motherboard. You will see that it is pretty easy if you lift in the proper spot. Note that there is a little plastic lip that prevents you from lifting in the near right corner. Of course, make sure you remove all 5 screws first. When removing the mother board, the screws you're interested in have a double white circle silk screened on them (makes it easy to remember).
 On many units, you wll be able to identify which screws to unscrew as they are outlines with double white colored circles.
 Step 13 - If you have removed the motherboard, on the bottom side you will see the connector for the backup battery (Picture 13). Simply unplug the battery and insert your new one if that is what you are doing. It is a Toshiba IVR 2025.
Thanks to John Smart for the following: Coin cell batteries have four digit numbers (2025, 2032, etc.) with letters (IVR, VL, DL, CR) in front of them. The letters are important. The numbers indicate different widths and thicknesses of the cells. MP780's come with a 2025 cell (20 mm x 2.5mm) which gives you a 150 mAh charge rating. The MPros use a rechargeable Lithium battery, not like your standard watch battery. When taking the leads off the original battery, you might use an Exacto knife and try to slowly cut through the two spot welds behind the leads on each side of the battery, while holding it with pliers. If you break the leads at the welds, you can always cut back the insulation on the original wires and make the leads a bit longer. Next step is to spot-solder the leads to the new battery (one spot on each side will do, and don't build it up too thick). When you've finished, wrap the battery in a little bit of electrical tape, or cellophane, so you don't have to worry about it oxidizing. You're done! Now you get to put your revitalized unit back together again.   The following steps are only if you need to replace the LCD or digitizer.
Step 14 - If you want to work on the lid part, it is not too hard. First, separate the lid from the keyboard by opening the hinge to a fully open position. Experiment with the hinge location and you will see that it needs to be in a certain position to separate the lid from the top half of the bottom case. GRASP AND MOVE THE HINGE ONLY BY THE METAL PORTION (Picture 14) otherwise you might break the delicate plastic. Also be very careful of the lcd ribbon cable. It is very fragile and easy to tear if you get too rough.  Step 15 - To get to the lcd inside the lid, first remove the screw cover. It is the small plastic black/gray colored circle you see in picture 15. It is simply stuck into place with adhesive. When you remove it you will see a Philips type screw, remove it too.
 Step 16 - Now if you look along the edge of the lid, on the side that had the hinges, you will see some slots (Picture 16). Insert the tip of your tiny flat head screwdriver in the slot while applying mild pressure to separate the two halves of the lid. They will come apart a little bit at a time, just like the keyboard did from the lower case half. Be careful and move in small steps.
 When you get to the hinge itself, there is a clasp you have to unlock on each hinge. (Picture 17) Simply pry up the lock just enough to separate the parts. Work yourself all the way around the lid and it will separate into two halves easily.  Step 17 - If any parts fall out (they shouldn't) like the lid clasp/locking mechanism, this is what they look like and how they should fit together.
 Step 18 - Now you can see the lcd and digitizer in the top lid half. To remove the lcd, simply unscrew the 4 screws that my arrows are pointing to. It should easily lift out as a single unit with the backlight daughter board attached. Again, note how the ribbon cable is threaded through the hinge. It is delicate, so be careful. DO I NEED TO SAY DON'T SLIP WITH THE SCREWDRIVER HERE…YOU CAN DAMAGE THE DIGITZER EASILY AND PERMANENTLY IF YOU DO!
 Step 19 - The LCD is the part of the screen that shows the color images. The digitizer is an acrylic clear plastic screen that sits just in front of the LCD. It has micro-circuitry etched into it that senses touching to the screen. The two are held together by a small adhesive gasket that is sticky on both sides. To separate the digitizer from the LCD, insert a NEW SHARP Xacto knife blade between the digitizer and the LCD. Cut through the adhesive gasket, and work yourself completely around the LCD/Digitizer panel until you have the two halves separated. Be especially careful when you near the delicate ribbon cable connectors. Don't try to pull the parts apart until you have cut the gasket completely. If you are replacing the LCD or the digitizer, you can reassemble the two pieces into a single unit again using simple Scotch type double backed tape. Note that the gasket is the light greenish colored strip surrounding the screen.
 Here is a picture of a successful screen disassembly by Mike Welch. You can see the lid, the lcd, the digitizer to the left and below with the backlight daughterboard and the reflector.
Reassembly Final step - To reassemble, just reverse the process. Be careful, it is tricky sometimes to remember to get the battery lock plastic switch in place and the clear plastic power led lens in place and the keyboard back on without everything falling all over the place. One thing worth noting on reassembly: WATCH the little black pin on the left near the back that is used to tell the notebook when the lid is closed.  When it comes time to attach the LCD lid unit to the base unit, move the hinge to where it can be screwed to the base using the two small machine screws you first removed. Once you have these two screws intact, it is easy to connect the LCD ribbon cable to the motherboard. On reassembly: make sure the ribbon cables are straight. If they're crooked, reseat them. I then snap the keyboard in place. For the 780 be sure to also reconnect the thumbwheel wires. BEFORE SNAPPING THE KEYBOARD INTO PLACE: Be sure to straighten the two ribbon cables that connect to the daughter boards. They should slide straight through the open slot. You can now connect the bottom case halves together. Aligning the ribbon cables into the connectors isn't hard, it is just a little tricky. I guess some of this will just have to be trial and error for you. Lastly, there aren't any torque settings when tightening the motherboard screws back down, so just tighten them till they are snug, you don't have to tighten them down until you hear a crack. |