Wednesday, December 06, 2006
from my former web site
trouble shooting
Schools do not teach trouble shooting. Why, I ask?
To hard to teach, some people cant learn?
Any way, I will try to teach it.
To understand how to fix things, you must know how to design them
The black box theory.
Things have inputs and outputs.
We shall view every thing between the input and output as a black box
“black box” refers to something that you do not know how it works.
So, you if you have the correct input you should have the correct output.
The basic logic is to view your item as a single black box at first, check the inputs and outputs.
If that fails to find the problem, keep dividing it into smaller boxes, and test the inputs and outputs of each black box till you find the problem, keep in mind there are things you can not test or take apart for testing, this should guide your decisions for how to divide the boxes.
Lets take a table lamp as an example, inputs are electricity from the wall and input from a switch, outputs are light.
Easy trouble shooting might be if the switch is off, you will get no light, solution is turn on the switch, proper operation needs proper inputs.
Next example, there is power, and the switch is on, and there is no light.
What to do? Do not do nothing, it will not get it to work.
One solution is to replace the black box (entire lamp ), kind of costly and may or may not be a good solution.
The next thing to try is to reduce the black box size ( smaller and easier things to deal with ).
We will now view the lamp as more than one black box connected together.
I will say, a power receiving box ( wall plug ), a switching box, and a light emitting box.
Seems reasonable, right? If you get this part wrong, it may increase time, and energy to fix it
We will figure out what input and output requirements each black box unit has, and determine if they are able to be tested.
Route one: Let us say that we have only our eyes to test things with.
The light emitting box is the only thing we can detect, I would start there, if it is broken, all other fixes may be not necessary and undetectable.
We test the bulb in another lamp, it works.
The switch is easy to get to in this case, so we replace it, still no light
next I will take apart the black box for the power plug, it seems simple enough, nothing looks broken.
all my black boxes seem to work, the problem must be the interconnections, of these boxes.
Upon inspection a wire between the power and the bulb has broken, problem found, but at high cost, time and a switch that may or may not be reusable.
Rout two: you have a meter that can test electricity.
You can now test the input and output of the switch, power plug, and input of the bulb.
It might be easier to test the points that are testable first, let us say that the wires on the switch are east to get to, we could quickly find out if anything up to and including the switch was working.
after testing it, the switch is getting, and sending power.
Ok, on to the next test, the bulb is getting power on one wire ( from the switch ), but no return connection ( the voltage is the same on the two wires ).
Ok, only one black boxes appear to have the wrong inputs, and the problem bust be an interconnect between the plug and the bulb, and upon inspection verifies a broken wire.
This sort of logic can be applied to many things.
Cost, ease of testing, and likely hood of certain parts to brake should be taken in to account.
Most people I see, stare blankly at their computer that is on (sound and lights as indicators), see no display and never figure out that the monitor is off.
Some trouble shooting is better than none, as they get laughed at all day long for this.
I hope this helped someone...
Adam