Hello Henry

Thank you for your support. Please excuse me for the long delay to answer you as well.

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Hi again Ben

The "finger-as-thermometer" test needs it's own qualities, the most critical one being the "rapid disengagement" function! One should presuppose that the test subject is highly hot.
Anyway, the alternative of throwing some drops of isopropyl alcohol on the suspected components is equally effective and harmless as well. A rapid evaporation reveals the problem at once.

Best Regards

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Hi Benjamin E,

I never give up with repairs, except if I face a wall. This merely means no spare part available and no modification applicable.
This was not the only time where I have seen many secondary problems being fixed automatically along with the main failure. On the contrary, I am quite familiar with this effect. The problem is always to apply the right strategy and tactics in troubleshooting. This is the key.
As for the fuse blow, your scenario is quite valid and highly possible. But if I judge from my findings with this case I tend to believe that this could happen accidentally, when the "gas" pedal was inadvertently pressed deeply while the truck was heavily loaded and passed over a pit on the ground at that moment. It seems to be an overloading case of its motor.
Thank you for your supporting comment.

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Personally, I would avoid using the finger test - especially after that one time when my fingerprint was burnt onto a very, very hot transistor ... ouch! 🙁

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Love the bit at the end where the forklift operator was ecstatic about all the other problems being fixed ... I bet with the number of times he called you out there, he was likely worried that the repairs would become too expensive!

Why do you think the fuse blew?
My guess is that the Microcontroller controls the motor H-bridge (or however it is hooked up), and a bad solder joint on the MCU caused the H-bridge to cross-conduct. But with those huge bus capacitors, that seems a bit far-fetched, considering the H-bridge was intact!!!
Perhaps it was just a co-incidence that the fuse failed not long after the forklift was returned.

-Ben

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Hi Mohamed

It was a real adventure indeed. I'm glad reading that you enjoyed it as well. Finally we all have unforgettable experiences.
As for the short circuit detector, although I didn't forget it at all, I still couldn't manage to find a solution. I am thinking of a quite different design of my own, an equally simple one with the one I used in the past, but up to now I could not find the time for experimenting with it. But I will...

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Thank you for your support. The fuse was remarkably huge indeed!
It makes sense anyway, as the nominal voltage of the system is only 48V. Its current rating represents therefore 32,4kW of peak power, the most of which is consumed by the motor that moves this very heavy truck...

Best Regards

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