Visual Inspection

Following this week’s theme of favorite class, I was going to start talking about how I liked Golden time at school on Friday afternoon, when we could bring in toys to play with. However, getting told off for wanting to take apart another kids “Simon Says” to find out how it works is maybe not what my fellow bloggers were looking for.

So I have picked my college course, which was called “Digital Fault Finding.” This class was aimed at understanding and repairing digital systems. One aspect was writing assembler code on old 8086 machines in order to understand the architecture. I remember very clearly being shown how to hack a .COM file and add our own code on the end as a way of understanding it. Yes you read that right – we were actively being shown how to write viruses!

Our Lecturer, who was called Dave, was a little under 7-foot tall Scottish chap who was a ex-STC electronics design engineer. You could hear him coming miles away as he wore genuine Scottish clogs.  However, there was no kilt as he wore a full, three-piece suit. He had the typical Scottish stereotype-image of wild red hair and a tatty beard. (Not that all Scots look like this, I have to point out!). He was also very loud, excitable, and could not spell a single word so dictated to us as he would not write on the blackboard. To finish off his image, and this is no lie, he also had a glass eye that would rotate during the class so it would point in odd directions.

So Dave, as you can see, was a odd chap but was really a great guy and funny. I learned a huge amount from him, which brings me to one particular lesson. In this lesson we were given project boards with the circuit drawn on the top, little springs to connect the wires and access test points. Dave would take the boards out of the back, flip them over,  and ‘generate’ a fault for us to find. Working in small groups, we would test the project board to find the fault and write it down. Now me being me, I could not resist flipping the project board over an looking at what was under there. To my surprise I found that the non-working IC had a blob of white paint on it.

As you can now tell, my group and I used the first rule of fault finding – visual inspection – for the remainder of the week. Dave,  unaware of this, was mystified as to how we were blasting though so many project boards and only taking minutes to fix them compared to 10’s of minutes the other groups were taking. He even added two or more faulty chips which slowed us down a little, but we were going great guns.

Now it’s not like we had to just list which IC was faulty. We also had to say why, so some work was still required. However I learnt, and so did Dave once we told him, that using your eyes is everything!