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Hi All,

The 1 amp fuse in the main "power in" socket in one of of my HPC 3060s just blew. Why?

A bit of poking around revealed something alarming! The live socket of the kettle lead that supplies it was partially melted, as was the live "in" pin. No bad connections were made in this chaos (the melting is only about 5mm across). Presumably the fuse had heated up sufficiently in a drop of molten plastic to blow. The kettle lead was in otherwise good condition - so I don't believe that it was the source of the resistance.

Now I could just grab another supply socket, fit it and carry on. But what I want to know is why did it overheat? (Yes, I have been thrashing out hour-long engraves for the last couple of days, but I've done that before.) Age? Bad luck? Or something more sinister?

Best,

James

An update!

I've taken apart the socket, and discovered that there are three pieces of metal that make up the live "in" pin. One that engages with the kettle lead, another that acts as a bridge, and a third that holds the end of the 1 amp fuse. Now if it was me designing this, I'd make sure that these three parts were soldered together - or at the very least, crimped tightly. But no - they just rest against each other with tongues and slots. So that might explain the heating, if a contact was a bit dodgy.

Maybe HPC should be advised that some of these components seem a bit dicky.

Cheers,

James

I had one that was arcing (I could hear it) so investigated and found the same - maybe the quality control on the sockets were a bit miss and hit! Let HPC know

Best
Dave

Nice one Dave - that's most helpful.

I had another suggestion offline, which went like this.

"Capacitors inside the power supply may have degraded, such that the PSU draws more current. This greater draw heats up the connection and eventually blows the fuse."

I don't like this for two reasons. One rational.

[*]The rational reason is that surely the fuse would have blown first, as soon as the PSU drew more current.
[*]The irrational one is because replacing a PSU is more expensive and I don't want it to be so!

Cheers,

James

I'm no electrical expert but maybe the rcd would trip if the PSU was drawing more current?

My money is on the connector but obviously keep an eye on it and chat to HPC

Best
Dave