Monday, November 12, 2012

Diagnosing Done Right

The other day My neighbors once again called on me to help them with some computer troubles. It's since been resolved and it was actually a REALLY simple problem, I didn't even really need to do anything, they eventually figured out before I could be available to take a look at it, but that's exactly why I'm writing this.

I like to think I'm good at fixing things, especially electronics, but honestly I don't know nearly enough about much of anything. I don't know what the Kernels in a computer do, I don't know how the circuitry in the motherboard works, hell I don't even know how the master/slave chain works if you have more than one hard drive. But what I DO know is how to diagnose a problem. Anyone can "fix" the majority of problems they encounter if they approach it the right way.

Specificity is Important

My neighbors told me that the computer "wouldn't turn on" and that was basically all I had to go on before I was able to physically see the machine. This is the first reason people have trouble fixing things. They don't really know what problems they are experiencing. If a computer "won't turn on" that might mean that when you push the power button absolutely nothing happens. It might mean that when you press the power button it lights up and then instantly dies. It could even mean that the computer technically powers up but nothing happens on the screen if they are not being specific.

Each one of these scenarios means very different things and if you do not differentiate between them you won't get very far in fixing your problems.

In this particular case the computer would power up if you hit the power button and the lights in the button would light up but then everything would turn off.

Determine What You Already Know

In each of those cases you can infer certain things based on the specific information you have just obtained. If  anything turns on or lights up when you hit the power button you can then safely say that the mechanism that is the power switch works whereas if nothing happens when you press it it is possible that the mechanism itself is broken.

Work Your Way In

Once you have collected all the information you have you want to start checking all potential points of failure starting on the outside and working your way in. For example, if the computer "won't turn on" the first potential point of failure is the power button itself. that is the very first thing that happens when you try to turn the computer on, pressing that power button.

So then you just need to ask yourself, is the button broken? and how can you tell? All you need to do to answer those is determine what you expect to happen when you press it, and whether or not that is what happens will tell you if it is broken. When you press the power button on a computer you expect its state to change. You expect parts to start moving (e.g fans), you expect sounds, you expect things to light up. If any of those things happen then the power button must work because you know that none of them would happen if you didn't hit that button. If nothing happens then the button is one possible problem.

Once you have determined that the power button works or have determined the power button may be broken, replaced it, and the computer STILL does not work you are ready to move to the next potential point of failure. when you press the power button all it does is tells the computer to draw power from whatever source that happens to be. if it's a laptop this would be the battery and if it's a desktop it would be the power supply and the outlet it's plugged into. If the power supply is broken it doesn't matter how many times you hit that button, there is simply no way for electricity to light anything up.

It's important that at each step you refresh your mental list of information. For example, if you are diagnosing the power supply of a desktop PC you need to once again determine what you expect to happen. Typically a power supply will have a fan in it and of course if it works it will be producing current. If you not that the fan starts to spin when you press the power button you now know that the outlet is supplying electricity to the power supply and that current is flowing through it and reaching the fan as well as anything else that lights up or moves or changes its state.

If there is anything that you expect to change states and does not when others act as they should this can tell you a lot as well. for example, if the power button lights up and the power supply turns on but something like a  CD drive or a USB port does not light up/receive power and it should then you can safely assume the fault is between that device and the things you determined to be functional.

Think of the computer as a circuit of information, or a chain of events. Pressing the power button -> Activates power supply -> Processor turns on -> Activates CD drive -> etc. In that scenario if the power supply and power button work and the CD drive does not function as it should (and you have no reason to suspect the CD drive is broken!) then the only missing link is the processor. Now, when i say "the processor" i mean the cpu, the ram, the video card, the sound card, the network card, the motherboard, all that junk. that may be a bit beyond the average user and actually fixing most of it is beyond my skills, but determining that the problem is there might save whoever you actually pay to fix it time trying to look for the problem. What is important is the process of determining information.

Now Put it to Use

In the end the laptop was simply out of batteries. Someone else who didn't know it was "broken" plugged it in to use it and it worked fine then but the battery was drained. If they had diagnosed it properly they would have been able to use their computer again in like five minutes, but instead they spent an entire day just thinking it was going to stay "broken" until I maybe fixed it.

When i press the power button does it light up? Yes.
Move to the battery.
Is there power in it? Yes there must be some.
Is there enough? Idk, let me plug it in.
Does it work now? Yup, it was just drained.

Very simple.

Now, in fairness, they said the battery was no where near empty when they last used it and the lights went on and off really fast so they didn't think it was the battery. Having said that, it never hurts to be thorough and you should assume as little as possible. If you can find out for sure then do it, don't just rely on your own memory or assumptions.

In Summary

If you follow these guidelines your life should be much simpler:
Be specific.
Gather all the information you can.
Start as far out as you can and work your way in one step at a time.

Thank you and enjoy your internet.