[SLL] Laptop getting a bit warm --> comments on disassembly and reassembly

[Nicholas Bodley]

{Woops -- I replied only to Robert Woodcock; meant this for SLL. --nb}
On Mon, 23 Jul 2007 12:59:15 -0400, Robert Woodcock <rcw at blarg.net> wrote:

[RW]
> I'd recommend doing all of this on a well-lit floor, so no parts can  
> fall and get lost. Also it's worth writing down which parts came off in  
> which order. You can figure it out again by trial and error but it saves  
> you a lot of backtracking, especially if you get interrupted halfway  
> through the process.

I save small, low disposable plastic cups and aluminum foil dishes to put  
small parts into. I love cats, but they can happily sabotage a task such  
as this! One sideswipe of a paw...

It's a good idea to look at each screw as you remove it to see whether  
it's the same as some others. A well-designed device won't have screws  
that look almost alike.

Do be aware of the difference in thread style between traditional machine  
screws, which fit into tapped (threaded) holes in metal, and screws for  
plastic, which displace the plastic in a hole to form mating threads.  
These screws look a lot like wood screws. When you reassemble, turn  
plastic screws backwards until you feel a little click; only then should  
you tighten them. Try, if possible, to re-use the existing threads in the  
plastic. It's very easy to badly damage them, so the screw barely holds,  
if you simply start tightening. (Seems that I also said this in another  
message...)

Watch repair people who work on unfamiliar and complicated movements  
arrange (or probably should arrange) screws and other parts in order,  
probably using plastic foam to hold them. Laptops, of course, are a  
different story, what with much-bigger parts.

Another way to keep screws straight is to reinsert them, loosely, after  
you've removed the part they were holding in place.

If you find that you've removed all the screws, but you still can't take  
the housing ("case") apart, look for a label that might be covering a  
screw or two. You can sometimes press and slide your finger along the  
surface of the label to detect a hollow spot, if the label isn't too  
stiff. It might help to peel the label slowly, if the adhesive is viscous.

Then, of course, there are often latches molded into the plastic to hold  
the housing together. They can be rather tricky to release, but shouldn't  
break if forced reasonably. I suspect that a Mac case-cracker tool is  
generally useful.

A while ago, I had a scrapped laptop, and really wanted to open up the  
display in the lid. I found that the screws had been covered neatly by  
melting the plastic to cover their heads! The manufacturer really didn't  
want people to disassemble the lid; not sure why. Found two different  
pieces of amazing light-redirecting film, part of the backlight diffuser.

[RW]
> Also make sure you're using the right screwdriver for the job. A #1  
> Phillips screwdriver will turn a #2 screw, but it'll also strip it a  
> little bit every time. Using the proper bit also means the screw is more  
> likely to stay on the screwdriver after you remove it from the chassis.

You can magnetize a screwdriver, which helps hold steel screws.  
Demagnetizing it is harder to do.

Japan has its own cross-recess standard; if you carefully grind the tip  
off a Phillips driver, it will fit Japanese-standard screws better.  
Drivers for Japanese screws are available, but not easy to find; a few  
electronics tool companies carry them.

The proper size Phillips driver usually has a diameter that looks much too  
big for the screw, as experienced techs. well know.

Don't use a worn, cheap Phillips driver, especially on something as nice  
as a laptop; get a set of good ones with bits of properly hardened tool  
steel.

Last, but by no means least, do be aware that you can create Major Grief  
by zapping those smaller-than-wee ICs with static that you can't even  
feel. Try to get an antistatic wrist strap, and connect it to earth  
ground. The chassis of an AC-line-powered tower that's plugged into a  
properly-wired outlet (earth ground) would be a good choice. These straps  
have a 1-megohm resistor built in, so you won't get zapped if you  
accidentally touch something live; however, for static, that resistor  
hardly matters -- the strap will keep you discharged very nicely. Even  
better, but getting costly, is an antistatic work mat also connected  
ultimately to earth ground.

At least, you can frequently touch the chassis (at the back) of the big  
machine; sliding on your chair (especially when dry, and in winter) can  
charge to to tens of kV. Also be aware of what your feet are doing. In  
industry, people wear heel grounding straps that extend inside their shoes  
and also fit over the outside of the heel of a shoe. These make sense only  
if the floor itself is relatively conductive.

You can also keep in touch with any metal frame parts, or items obviously  
connected to them; that can help.

Interesting that 100 volts (or less!) can degrade or destroy an IC;  
degradation is nasty, because it might not cause an outright failure.  
However, you probably won't feel the zap when you discharge yourself, if  
you're charged to less that 3,000 volts; no kidding. That 3-kV figure  
refers to your body, "freestanding" and relatively insulated from ground  
(such as by an insulating floor, or insulating footwear); it does not, of  
course, refer to touching a source of power at that voltage, which is  
really dangerous.

HTH,

--
Nicholas  B o d l e y
Waltham, Mass.
who was quite surprised to see a
heat pipe inside a laptop, years ago.