Taking Apart A Computer - Removing Components

Opening the case (and didn't come across one of those screwless cases)  We're going to disassemble the entire computer today, so be prepared.  You should have a cup/baggy ready for screws and washers, some anti-static bags, as well as your toolbox handy.

Before You Begin - Make Some Notes

Most experienced technicians skip this step.  As you become more acquainted with a computer, you normally will be able to as well.  The trick is to be able to recognize something that you haven't seen before, and document it so you can duplicate the setup.  Basically, if you don't know what it is, document it before you take it apart.

Removing Adaptor Cards

The first step to disassembly is to remove the adaptor cards.  Most of them simply plug into an ISA, PCI, or AGP slot, and are held in with a single screw rear the rear of the case.  Assuming you've already removed any attached cables, remove the screw and store is safely.  (You have no idea how frustrating searching for screws can be.)  Now pull the card away from the motherboard.  You should pull straight if possible, as it is less destructive to the card.  If you have to wiggle it a bit, try not to pull it too far, as the pin contacts can damage the inside of the ISA or PCI slot.  Don't touch the chips or the circuits if you can avoid it, as this will also do damage to the card.

Put each card inside an anti-static bag as soon as you can.  You won't do any damage to the card right away by leaving it exposed, but every bit of dust and electrical charge it picks up shortens it's life in the long run.

Storage Drives

Next you must remove the hard drives and other drives mounted in the case.  First remove the cables plugged into the back of each device.  Most of the cables are pretty standard, and don't require you to remember exactly what drive they were plugged in to.  We'll deal with that when we re-assemble the computer.  The only exception is older CD-ROM drives that plug into the sound card.  Make sure you make a note of this, because it can be a pain trying to remember it later.

Now you must determine how the drives are held in.  99.44% of the time they are held in by 2, 3, 4, 5, 6, 7, or 8 screws.  (Looking at my main hard drive, it has 1 holding it in right now.......   Bad technician... BAD TECHNICIAN!!!)   If it's not held in by screws, prepare for another screwless case debacle.  You'll have to figure out the right combination of levers and slides that allow you to remove the drive.

Remove all the screws that connect the drives to the metal chassis ONLY.  Don't unscrew the chassis screws that connect to other parts of the chassis unless the case is so poorly designed you have to.  Then slide each drive backwards or forwards until it is free of the computer.  Store your screws with your adaptor card screws, and store the drives in anti-static bags.

Disconnecting Power

Next we're going to separate the power supply from the motherboard.  This comes in two stages.

Stage #1 - Look for the AT or ATX-style power connector.  It is either two-9 pin connectors (AT) or a single 20 pin connector. (ATX)  The ATX connector just needs to be unlatched and pulled off.  The AT connectors might require unlatching and a little force.  Pull them straight up, and then move them forward to pull them off their slides.  (Remember when you go to put them back on that the black wires ALWAYS go beside each other.)

Stage #2 - Look for the connectors that connect the power supply to the pin connectors for the case.  AT cases will most often connect straight from the power supply to the front panel on the case.  ATX cases do this through the motherboard.  Pulling these connectors straight up will remove them, and you might as well disconnect all the other wires from the case to the motherboard at the same time.

BUT WAIT!!!!  Notice how there's between 5 and 8 connections there?  Did you happen to mark them down?  Each motherboard has it's own pin layout for how those connectors work.  Some work in both directions, meaning you can't put a cable on backwards.  Others will stop the system from booting when put on backwards.  Mark the position AND polarity of each connection before you even think of pulling it off.  

And if you pulled them off before you read this paragraph, you have just learned a valuable lesson.  ALWAYS read the entire instruction set before attempting to start a project.  It's better to find a problem exists before you start working on a project than to be half-done and stuck.  Hopefully you didn't yank any wires, and hopefully you'll think twice before you ever do again.

Removing The Motherboard

Now comes the fun part.  If you're lucky, you can remove two or three screws now and one side of the case with the motherboard attached will come loose.  If not, look again...  95% of cases do this.  It's just finding out how that's the problem.  The whole metal plate should come out of the case with the motherboard attached.  If you unscrew the plate and it doesn't come loose, make sure you have ALL the adaptor cards and cables removed.

Once you have the motherboard on the chassis in front of you, look for the screws that attach it.  Normally there will be a minimum of 3 and a maximum of 7.  Unscrew each connection.  Make sure you save the screws AND the washers.  lift the motherboard off, and examine how it was connected to the plate.  Normally standoffs of a plastic or metal variety are used.  If they are metal, look for more washers.  

If you plan on re-using the case, make sure you store the standoffs, screws, and washers all in a safe place.  You'll need them again later.

Cleaning Up

Place your motherboard on top of an anti-static bag on top of a non-conductive surface.  You'll notice there are RAM SIMMs/DIMMs still attached, as well as the CPU and fan/heat sink.  Let's work on the RAM first.

If you have 30 or 72 pin SIMMs installed, you'll notice little metal tabs on either side of the SIMM.  Pull then back, and push the SIMM forward.  The SIMM will come out.  DIMM's use levers on either side of the DIMM as well.  Push the lever away from the DIMM and the DIMM will come loose.  Store each SIMM and/or DIMM in it's own anti-static bag.

Next, examine the latching mechanism for the fan/heat sink.  Normally it's hooked on, and the hook merely has to be pushed down to release the fan and heat sink.  ZIF socketed processors only need the ZIF socket level released to loosen the processor.  PGA requires you to pull the chip out like an adaptor card.  Personally, I'd leave the chip in unless you A) need the chip somewhere else B) need to put a new chip in, or C) have a death wish.  All those little pins on the bottom have to be pointing straight down.  Ever tried straightening one of those damn things?  It's not fun.  So keep the chip on the motherboard as long as you can, or if you can store it safely.

Be careful with processors.  If you take them out too quickly, they can be quite hot.  If your 200 Degree processor contacts your 80 degree fingers, the next contact will probably be the processor and the floor.  I've dropped a processor before.  They crack real nice.  And all those tiny wires in there won't work ever again, because you can't fix a processor.

Finally, place all your extra items lying around into proper packaging.  Components go in anti-static bags, tools back in your tool box, and screws and washers store nicely in sandwich bags with zip lock tops.  Anything you loose will make it that much harder to re-assemble next week.