Here is how to trouble shoot stuff that appears to have errors or defects.

Let us take a simple example.
You turn on a light switch, and no light shows from the light bulb.

First, we make a list of what are really guesses that we think could cause the problem.

1 light bulb defective.
2 no power to bulb.
3 no power to house.
4 defective bulb holder
5 defective wires to bulb holder
6 defective light switch
7 blown fuse or contact breaker.
8 bulb has been stolen!

Ok, so we make a list like the one above. These are just guesses, but some are more likely than others. We know this because of experience, the fact is that bulbs go bad after a while. But to assume it is the bulb would not be trouble-shooting the issue. Bear in mind that the bulb might have blown, and in so doing, triggered the breaker or fuse to blow. Ok, in reality, you might prefer to select the most likely, but I am going to be random and assume that I have no past experience with light bulbs.

OK, I have 8 possible things, so I take 4 of them, let's say numbers 1 to 4.
I check them one by one.
It is no problem to me if I find that none of the 4 are the cause, I am troubleshooting, so that will eliminate 4 possibilities.

So, let assume I get the following results.
I check another room and the light works, so there is power to the house, and a good bulb there.
I take that bulb and put it in the room where there is no light. It fails to light up.
I check to see if there is power to the bulb holder, and find that there is none at the contacts where the bulb gets its power.

So, I make a list.
It is not the bulb
Number 2 is true, but might be other reasons.
I know that there is power to the house.
It might, or not, be a defective bulb holder.

Right, now we move on to the other 4.
We find the wires to bulb holder are good using a meter.
We check from those wires to the socket contacts where the bulb fits into the holder, and find it OK
We check the fuse using a meter and it is good.
We know that the bulb was not stolen.
The switch appears to click OK, but we do not check it fully yet.

Here's what we now know:
It is not the bulb
Number 2 is true, but might be other reasons.
I know that there is power to the house.
It is not a defective bulb holder.
We know that the wires to the bulb holder are OK
The fuse is good.

So, i know this gets a bit tiresome, but we have divided what we think it might be, and checked each guess. We have a good bulb, holder, and wires, and the fuse is good. We think the switch is good, but haven't fully checked it, and we don't know if there is power coming past the fuse, although we know the fuse itself is good.

Time for a list again.
Here are the new guesses:
There is no power to the fuse
There is power to the fuse but not on the bulb side of the fuse, despite the fuse being good.
It could be the wires from the fuse to the switch
It could be the switch itself.

So, we divide and take the first two:
We find power to the fuse.
We replace the fuse into its socket and find there is power out of the fuse.
We go to the switch, and find the light goes on.

The problem was that there was no power on the switch side of the fuse, but when we replaced the fuse, we re-made the contact. The problem was a loose fuse. If on the last test of the switch the light stayed off, then it would probably be the switch that was bad.

There are no comments to this entry.