Well, I just had a conversation with my old electronics engineer dad. Not that he has any answers. But we both concluded that the best place to start is to replace the fuse holder, and get things back to where they were before it was blowing.

The reason being, even with a fast blow 15 amp fuse, this machine runs for quite a while before the fuse melts. One side of the fuse is HOT. The other is not. It seems to point at bad connections that got this mess going.

So I'm going to start there. I mean, unless there's a short, the worst case is the 14+ amps all of the time. I think we just degraded the circuit board traces and fuse holder.

I'll report back with the results.

I can safely say the machine is fixed. I've had it running for a week without any trouble.

The problem was what I had expected. I sucked out the fuse clips, and installed new ones. I also ran solid copper in lieu of the traces on the board, over to the relay.

I don't know what caused the initial problem. I have a suspicion. The traces were compromised. It's a double sided board, and one side had a nearly blown trace. Also, the fuse clips are rated at 15 amps, which is pretty much what they're operating at. That's probably a weak point.

Before I pulled things apart, I did a run test. I discovered that the fuse clips were heating up and losing their grip on the fuse. Once that happened things started heating up. The circuit board is actually burned at each end of the fuse. It was getting so hot it just melted fuses.

At any rate, it is running happily.

Good show!! It sounds like the fuse setup was under-designed for the load. Loose load carrying components heat up, heat causes more looseness=failure. It's an old story. Glad to see a happy outcome.
KDM

At any rate, it is running happily.

That's a good result for you.

Take my pessimism kindly. It seems very unlikely that a fault of this nature would show up on one and only one machine. For a long time on the alt.coffee newsgroup, this gentleman handled the sale of Reneka Techno machines into the US - http://www.justespresso.com/index.htm . It may be worthwhile to send him an email and reference this thread.

If we are talking the small, 1inch glass type fuse, with clips soldered to a p.c. board running 15 amps; I'd say that is trouble waiting to happen. Especially if it is running for long periods in an otherwise high temp area. Of course I think everything should be industrial strength! My bad.
KDM