In my normal job, I'm a leader of a small team that maintains, fault finds and repairs electrical control systems. Hence in addition to tinkering with 1980s and 1990s computers and various other electronic and electrical items at home, I have a good understanding of investigating faults and failures in electric and electronic systems.
Having a working machine (or a nearly working machine, even if in a poor condition) mutilated to inflict an abstract fault does not appeal to me.
Yes, some of the 'fun' is in the chase. But the reasons for helping forum members to repair their computer also includes:
- Helping people with a problem (it's a good feeling when the owner/person doing the work reports back that they got it working ),
- It often helps other people (both registered forum members and non-members),
- It kinda documents the problem, so that if the same fault occurs again on another machine years later, hopefully either someone will remember, or a search will find the relevant post,
- Keeps more of these old machines going (we don't want working examples to become overpriced R@RE items on auction sites),
- Environmentally, in general it's far better to repair equipment than to dispose of it.
In terms of actual fault finding/fault location. It is a combination of skills, knowledge, experience, understanding of the system and history. Both of the machine (by this, I mean that particular model, not necessarily that particular machine, although knowing the machines history sometimes does help) and of electronics and computer systems in general. This includes 'stock' faults (very common failures) such as 'my Beeb starting smoking and gave off an unpleasant smell'.
Bouncing ideas and suggestions around in the forum also helps as it allows other members to comment.
Computers in general, are actually tricky beasts to fault find on, as there are so many possible defects that can cause the same, or very similar symptoms. Faults that stop the CPU from running can also make it very hard to diagnose the cause of the problem. And that's when you have the machine in front of you with hundreds of pounds of test equipment hooked up to it...
And don't get me started on repetitive intermittent/erratic faults. In my job, these are the Bain of my life. You travel 20, 30 or 40 miles, only to find the system working. Then the next day, or a couple of days later, it fails again... The user asks how long to fix it and so you go looking for a tree to headbutt...
So I don't think you will get too many replies to a post where a machine has been deliberately broken.