About 8 years ago my company sold a good customer of ours an ex demo shrink wrap machine, £40,000 worth of equipment. We always asked that a customer gets the essentials to the machine (3 phase power, air etc etc) then leave it well alone.
Well this customer is like a kid with a new toy and can't wait to switch it on. He wires it up and BANG!!!! Now you or I might be put off by this but after quickly switching it off he switches it back on, god knows what he thought might happen, but, you've guessed it, BANG!!!!
After a little bit of BS on his side (I never touched it, I never switched it on etc etc) we were obviously able to prove as an ex demo it was working 24 hours before it was delivered.
Turns out he had lived up a neutral. My machines don't much like 240v down there and it turns out he had blown up 2 Lenze motor controllers. It would have been one, but he had switched it on again hadn't he. Cost for new one (programmed direct from machinery manufacturer, £850 each)
Oh well, we all learn by our mistakes, or so you would think.
Luckily he has decided to stay with me after I was made redundent in April and requested that I go in last Thursday and install a second hand machine he had picked up. I couldn't believe it when I arrived, he had done exactley the same thing and blown up 2 motor controllers, again!!!!!
As I work for myself now I decided to take a look inside (wasn't allowed to do that at my last company, not as much profit). Found a varistor in each one blown to kingdom come.
Found the varistor at RS, 47p each, soldered them onto the PCB and job done. Saved him £1600+!!!
Although I never made as much cash out of that, the great feeling I got from making something work with a little bit of savvy and the appriciation I got from the customer was fantastic!
End of the day, he's a great customer, one of the nicest blokes I know, and I need to keep hold of them ones!!!!