This is one of the most important things to learn in taking the TESDA NC II Computer Servicing Exam. You need to learn the step by step procedure on how to open and disassemble a system unit. There are various design of computer casing and before opening you need to check and see how you will start the system unit dis-assembly. Here we are going to use a mini-tower casing as our model, mini-tower casing design is the most easiest to disassemble, however that would depend on the brand and model.
- It's Not a Race, take a slow relaxed approach, discuss, question and research each component as it's removed.
- Fall back on your own knowledge, use the Internet, your books and resource material. It's impossible to retain all the information, so one of the most important computer skills you can learn is how to research and use your resources to find what you need.
Questions to Think About or Discuss as you Disassemble
- Should I document everything I do or everything I remove?
- Am I taking the best ESD precautions available to me right now?
- When you remove an expansion card what kind of card is it?
- When removing a drive, what kind of drive is it?
- When removing wires or cables, what are the cables for?
- Am I still taking proper ESD precautions and is my anti-static strap still hooked up?
- Look at the motherboard again when there's not so much in the way. Can you point out the CPU?
Before You Begin
- Have a pen and paper ready. Documentation is real important.
- Make sure you have the tools you need and they're all close by and handy.
- Be sure to have a container to keep the screws in.
- Make sure you have the resource material, drivers or software that you may need.
- If possible, enter the CMOS setup and record the information available.
- Disassembly is major surgery, do a full backup of the system.
How to Remove the System Unit Cover
The standard way of removing mini-tower cases used to be to undo
4-6 screws on the back of the case, slide the cover back about an inch and lift
it off. If there is no manual, then a little time taken for careful inspection
may be in order. Here are some things to remember:
- Don't Force Anything. If it has to be forced, it will probably break. If there are no screws on the back of the case for the cover, check the plastic face-plate on the front. Some pry off to reveal screws or release levers (remember, careful inspection). If everything on the front has its own bezel around it (including the LEDs) then maybe the plastic front pops off (or maybe the case slides off the front).
- Make sure any screws removed are for the cover. You don't want to unscrew the power supply by accident and have it fall inside your computer. That's a bad thing.
- After the case is removed, place it in a safe place, where it won't get knocked of a table, kicked or stepped on and bent.
How to Remove Adapter Cards
- Again, documentation is very important. Since some of the module cards have a specific configuration, like for example a 16-bit ISA card will probably work in any 16-bit ISA slot, but there may be a reason it's in that particular one. Document the type of card and which slot it comes from.
- Check the card for any cables or wires that might be attached and decide if it would be easier to remove them before or after you remove the card.
- Undo the screw that holds the card in place.
- Grab the card by its edges, front and back, and gently rock it lengthwise to release it. Do not wiggle it side to side as you can break the card, the slot, or the solder. Sometimes it helps to grasp the inside corner of the card with one hand and place a finger from the other hand under the associated port out the back of the computer to pry up the one end of the card.
- Once the card is removed, you may want to record any jumper settings you see, just in case one is accidentally dislodged. Try to store the card in an antistatic bag. If you don't plan on replacing the card then a cover should be installed over the slot opening.
How to Remove Drives From System Unit Bay
- Removing drives is not that difficult. They usually have a power connector and a data cable attached from the device to a controller card or a connector on the motherboard. CD-ROMs may have an analog cable connected to the sound card.
- The power will be attached using one of two connectors, a large Molex connector or a smaller Berg connector for the floppy drive. The Molex connector may need to be wiggled slightly from side to side while applying gentle pressure outwards. The Berg connector may just pull straight out or it may have a small tab that has to be lifted with a tiny flat screwdriver.
- The data cables need to be documented. Remember the pin one rule. Know where each one goes before you pull it out and record its orientation (which side is the stripe on, where is pin 1?). Pull data cables gently and carefully.
- Can the entire drive bay be removed? Does the drive come out the back of the bay or does it slide out the front. If a bay is removable, you may have to remove some screws or unclip a lever then slide the bay back and off. If the bay is not removable, there should be access ports on the other side of the case that allow for access to those screws.
How to Remove Memory Module
- SIMM - gently push back the metal tabs holding the SIMM in the socket. Tilt the SIMM away from the tabs to about a 45% angle. It should now lift out. Put each SIMM in its own protective bag.
- DIMM- There are plastic tabs on the end of the DIMM socket. Push the tabs down and away from the socket. The DIMM should lift slightly. Now you can grab it by the edges and place it in a separate antistatic bag.
How to Remove Internal Power Supply
- Make sure it's unplugged.
- All power connectors should be removed, including the connection to the motherboard and any auxiliary fans. Watch the little plastic tabs on ATX connectors (you'ld rather not break them). AT power supplies have a two piece power connector that may be labeled P-8 and P-9. Make note of the orientation. The black wires should be in the middle, black to black.
- Remove the connection to the remote power switch at the front of the case. Orientation of the colored wires at this switch is critical. Make sure you document well, and during re-assembly plug the computer into a fused surge protector before turning it on (this could save your motherboard and components from melting if you've reconnected improperly). If you're putting the same power supply back, it's better to remove the entire switch and leave the connectors intact. The remote switch on an ATX form factor attaches to the motherboard.
- Remove the four screws at the back of the case and gently slide the power supply out of the case. While removing these screws, hold onto the power supply. You don't want it falling into the case.
How to Remove Mother Board
- Document and remove all wire attachments to the motherboard. (Some of these have Pin 1 designations also.)
- Most cases have a removable panel that the motherboard is attached to. By removing a couple of screws the panel can be taken off and you can gain much better access to the motherboard. Again, a little investigation can save a lot of trouble.
- There is usually 2 or 3 screws holding down newer motherboards. Make sure you've got the right ones and remove them.
- Motherboards sit on plastic or brass standoffs that keep the traces and solder from touching.