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I would add that fuses would blow .
What’s your definition of widespread?
Does some parts of the circuit still work without the fuse blowing?
Martin
What’s your definition of widespread?
Does some parts of the circuit still work without the fuse blowing?
Martin
Thank you. That’s helpful.
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Hi Martin. It’s a PCB for a sub woofer. The fuse keeps blowing. I could that a mosfet was shot. Took it out of circuit and then i went testing for continuity generally and found that there were points in numerous places close to each other that were showing continuity. So i guess something else has blown and is now connecting all these points together. I thought diodes would be a candidate for doing this. But I’m a noob so hence the question. The board is 2 sided so removing components to test is really difficult and is doing damage to the traces so trying to minimise this.
Potentially - and quite likely - but components fail far, far, faster than fuses do so the damage is done well after the fuse considered blowing itself up!
For many circuits a diode failure in the power supply might be catastrophic but there are other types of power supply that have regulators between the fuses and the main circuitry and the regulators might 'save' the circuit.
Too many variables to be specific and it's usually a case of working your way through the circuitry to discover what did what to what (if you get my drift?)
Generally speaking, a fuse would blow with a short across the mains, be it a X2 cap , bridge diode or any combination of both.
If you guys have a better or definite repair idea, speak up. I see nothing but question mine.
Isn't the whole idea of a fuse being the "weak link" that fails first to protect the rest of the components?
Most fuses (at least in domestic appliances) are there to prevent over-heating of the power supply cable.
Not at all.
In most cases the fuse is there to protect the CABLE supplying the voltage to the equipment. There is no mechanical fuse in existence that can operate quickly enough to prevent electronics blowing up.
If the fuse is internal t the equipment then it protects from fire by overheating.
Really? So the fuse is just there to prevent fires and injury outside the box. They don't give a toss about the appiance itself? I feel like I'm being told there is no Santa Claus. What other home truths do I need to learn about the grown up electronics world??
Your right to an extent.
Preventing fires isn't alwsys a fuses sole purpose.
It depends on the application but It can mitigate damage to circuit board traces and more robust components such as transformers, rectifiers etc.
OTOH,
By the time It takes to blow even a fast acting fuse a sensitive electronic component will usually see too much current to survive.
PS; Santa lives on in out hearts.
And the Easter bunny!
TINSTAAFL - (there is no such thing as a free lunch)
Buy cheap, buy twice
....
there's loads! Google Murphy's Law!
bertus
Moderator
There SHOULD be continuity from various points on the PCB. You just need to know where.
Is the mosfet bad? You only said you took it out of circuit.
Martin
