Tools of the trade
  • Phillips-head screwdriver
  • Small flat-head screwdriver
  • Tweezers
  • Torx screwdriver - for old Macs & Compaq & HP’s. very A+

  • Extractor - in lieu of long skinny fingers
  • Multimeter

Convenience tools

  • Compressed air very A+
  • Contact cleaner very A+ (or white eraser)
  • Chip extractor - maybe
  • Pen and paper for notes
  • Needle nose pliers
  • Flashlight
  • Magnifying glass - if age > 40
  • Small baggies for little stuff
  • Bootable rescue disks
  • Virus detection CD
  • Diagnostic software and cards
  • Utility software


Protect yourself, the hardware & the software

Protecting the hardware

Electrostatic discharge (ESD), commonly known as static electricity, can be annoying to humans but absolutely fatal to computer components.

Static electricity is caused by friction or by the sudden separation of dissimilar materials. Static charges can build up on the surfaces of non-conductive surfaces like clothing or plastic.

These charges are then looking for a path back "home".

Some materials are easily conductive, like metal. When an ungrounded object with a static charge comes into contact with a grounded conductor the static charge will want to flow to the conductor or ground.

Static breakdown

Feel static = 3000 volts

Hear static = 6000 volts

See static = 8000 volts

As little as 30 volts can destroy some kinds of integrated circuits! Typical computer circuits called CMOS circuits can be destroyed with around 250 volts.

 

Things you can do - very A+

  • Leave computer plugged in (this protects the computer – not you!)
  • Equalize the charge by touching the computer’s metal chassis
  • Ground mat or ground strap

                   What is wrong here?
  • Static shielding bags
  • Control humidity (cool and dry – static high)
  • Take your shoes and socks off

     

    EMI – Electro Magnetic Interference - Electrical "noise"

    ESD can be fatal for computer hardware. EMI (electro-mechanical interference) is recoverable. very A+

 

From the don't run with scissors file

  • Don't touch chips or edge connectors
  • Don’t stack boards
  • Don’t touch chips with magnetized screwdriver
  • Don't lay components on Styrofoam - use a grounded mat, static bag, or closed-cell foam
  • Don't leave the PC on when you move it
  • Don’t ground yourself if you are working inside a monitor - very A+
  • Don't put disks near magnets, extreme heat & cold
  • Don’t touch disk or tape surface

Remember, you have been warned…

What does the following have to do with fixing computers?

"Al, bent over the wheel, kept shifting eyes from the road to the instrument panel, watching the ammeter needle, which jerked suspiciously, watching the oil gauge and the heat indicator. And his mind was cataloguing weak points about the car. He listened to the whine, which might be the rear end, dry; and he listened to tappets lifting and falling. He kept his hand on the gear lever, feeling the turning gears through it."

"Listen to the motor. Listen to the wheels. Listen with your ears and with your hands on the steering wheel; listen with the palm of your hand on the gearshift lever; listen with your feet on the floorboards. Listen to the pounding old jalopy with all your senses; for a change of tone, what a variation of rhythm might mean. That rattle - that's tappets. Don't hurt a bit. Tappets can rattle till Jesus comes again without no harm. But that thudding as the car moves along - can't hear that - just kind of feel it. Maybe oil isn't gettin' someplace. Maybe a bearing's startin' to go..."

The Grapes Of Wrath
John Steinbeck

 

TROUBLESHOOTING FUNDAMENTALS

The process of finding the source of problems and fixing them is called troubleshooting.  Troubleshooting is a combination of skills and attitude.

Attitude check: patience?

In troubleshooting, as in any other human endeavor, you must have the right attitude to succeed. You CAN solve it. It's not magic -- there's always an explanation. Don't try to FIX it, just try to narrow it down.

"Each mistake brings me closer to my solution" – Thomas Edison


Limitations:
Several factors combine to make troubleshooting a challenge, even to those employing sound troubleshooting techniques.


Intermittents and reproducibles

A Reproducible is:

A symptom that can be consistently reproduced using a known procedure.

An Intermittent is:

A symptom for which there is no known procedure to consistently reproduce it.


Here are four troubleshooting techniques.

1. DIVIDE AND CONQUER – Binary Reduction

Note that it is a mathematical certainty that you will solve any reproducible problem in a system for which you have knowledge and/or system documentation.


Mathematics tells us the fastest way (using a system) to find a single element in an ordered set is a binary search (or binary reduction). A binary search is the process of repeatedly ruling out half the remaining search area until the element is found.

Unfortunately, reality is not sequential

With computers most things are never really "in half" so you need to learn how to isolate "groups" of problems and tackle them discretely.

The problems that you might encounter can be divided into two basic categories: hardware and software.

  • Hardware problems can be further divided into being of an electrical or a mechanical nature.

You will know you have a hardware problem if, for example, the screen is blank, the computer cannot recognize the disk drives, or you get an error message during the Power-On Self Test (POST).
  • Software problems can occur at several levels. Both your operating system and your software application programs are capable of generating errors and error messages.

If you encounter a software error, try to determine if the error message is from your operating system or from an application program, and refer to the appropriate manual for possible remedies.

NOTE: Implicit in all this is that if you keep narrowing it down, whether binary or not, as long as you don't repeatedly double back in areas you've already tested, it is a MATHEMATICAL CERTAINTY you'll eventually solve the problem.

What makes the system you're troubleshooting an ordered set is your knowledge of it, reinforced by manuals and documentation. It's that knowledge that allows you to devise tests to split the search area in half.

One way to begin a binary reduction is to ask; "what’s changed?" Getting the troubleshooting process started with a customer is very A+.

 

2. SWAP WITH THE KNOWN GOOD

One easy way begin a binary reduction is to replace a questionable component with one that you know works.

PC's are made up of less than a dozen components.  Swap component with a component that you know is good. FRU - Field Replaceable Units - very A+. Basically anything that doesn’t have to be soldered in or cracked open.

 

3. INCREMENTAL TESTING

Make one change then test.  Make another then test.  An example would be to remove all unnecessary expansion cards and install them one at a time until a problem begins.

What I do is essentially start with the simplest possible system and start adding and testing, adding and testing…

 

4. SCIENTIFIC METHOD (via Physics 109)

First, what is science?

Science is a branch of study that is concerned with collecting facts and forming rules to explain them. The method of doing this is called the scientific method.

This "method" consists of systematic observation, the forming of a hypothesis (assumption), devising a test for the hypothesis and then validating the results of the test.

The scientific method:

  1. What did you observe?
  2. What is your hypothesis?
  3. What test did you devise to test your hypothesis?
  4. Were you correct - if no, go back to step 2

ACCEPTABLE TROUBLESHOOTING TECHNIQUES

  • Divide and conquer (binary reduction)
  • Swap with the known good
  • Incremental testing
  • Scientific method

Edited (2003) By Vlad Magero