Troubleshooting Tips Mini Blowing Fuses

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java man
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Troubleshooting Tips Mini Blowing Fuses

Post by java man »

My Mini Vivaldi II is 11 years old, and has been a pretty reliable machine. I’ve changed the vibe pump, a steam valve, a solenoid and repaired a few minor leaks. Aside from that I’ve had 11 years of everyday service. It has a timer, the pressure modulator (preinfusion) and turns on via the timer 3x daily. I run it on 20 amps.

I had to replace a fuse a little over a year ago, but it was all good until a couple of weeks ago when it blew a fuse and kicked off the GFCI. I replaced the fuse and it blew again 2 days later. It also damaged the body of the fuse holder.

I replaced the fuse and holder, and disconnected the brew boiler leads. It came on when powered up, pulled a shot normally and no fuse problems. Next, I disconnected the steam boiler, reconnected the brew boiler, but the steam boiler wouldn’t turn on, I assume because the brew boiler wouldn’t come up to operating temperature.

How can I troubleshoot this to isolate whatever caused the fuses to blow?
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chas
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by chas »

Are you using the terms brew boiler and steam boiler backwards? Otherwise, I am not sure how you can get the brew boiler to heat up and then pull a shot with the brew boiler leads disconnected?
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by java man »

Sorry, the first one should have been steam boiler disconnected.

AFAIK, the steam boiler won’t heat up til the brew boiler has come up to temperature. This makes it hard to test whether the steam boiler alone will blow a fuse.

But I think I’ve moved past that.

With everything connected I was able to leave it on all day and make three cappuccinos, all with no problem. Sounds like the problem is intermittent. I can’t imagine I would get an intermittent failure of either boiler element. I haven’t a clue about how to troubleshoot this.
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by java man »

Update: Everything is back together. Mini Vivaldi is up and running. 10 days now with no blown fuse. No idea what caused it. I'll just carry on.
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by java man »

My Mini Vivaldi II has been running since Mar 2, but has blown 3 fuses during this period.

This week for the first time, a fuse blew while I was actually making a 6 oz. cappuccino, so I was able to observe what was happening.

I had prepped the PF, locked it into the brew head, and expressed the steam wand to clear accumulated water.

Both the steam boiler and the brew boiler heaters were drawing power. When I pressed the brew switch, the fuse blew.

This means that the combined draw of brew boiler, steam boiler and pump exceed the fuse capacity.

The heating elements in this machine are the original ones used since June 2009. The pump was replaced a couple of years ago.

Has anyone had boiler heaters that started to deteriorate before they shorted out completely?
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by goodboyr »

More likely its a deterioration of either the fuse holder or the main power connections. La Spaz uses pretty cheap plastic fuse holders and the connections sometimes oxidize, heat up and increase resistance and current draw. Same for the main power connections. So, if you are comfortable doing electrical work, you can pull off the covers, and look at the rear of the machine and at the fuse connections for signs of overheating and oxidation. I was getting fuses blowing on my Dream 20 amp unit, and that was the cause.
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by java man »

Thanks for the reply, Bob. I replaced the fuse holder in April, so it's probably not that.

On June 13 I decided to switch the machine over to 15 amp operation. That way, the group boiler and steam boiler should never operate simultaneously. 9 days later, no blown fuses, but it tripped the 20A GFCI this morning. I wasn't around when it happened so I can't say which boiler was operating at the time.

I don't see the number for Chris Coffee mechanics any more on their website. I'll try the chat to see if I can get some advice.
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by goodboyr »

Make sure you check the main power connections. Since you have eliminated the fuse as the source, these connections at the back of the machine on mine showed signs of oxidation and overheating as well.
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by chas »

From what I have heard from others on this Forum over the years, a tripping GFCI is normally due to moisture that gets inside the heater element''s metal jacket. When the element turns on, the water turns to steam and causes an unbalanced current between neutral and ground which trips the GFCI. This could happen in either heater element but has been seen much more often in the steam boiler element. Unfortunately, the only fix for the mini if it is the steam boiler is to purchase an entirely new boiler which is pricey since the steam boiler heater element is not replaceable on the Mini as it is on the plumbed in model.

The only easy way to be sure which heater element is the cause would be to press the front panel button that turns off the steam boiler. If you have no more issues then you have to get a new boiler. If it still happens then you need a new heater element and gasket for the coffee boiler.
Boiler Off.png
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BTW: The size of the breaker has no impact on GFCI operation. It only takes an unbalanced current greater than 5 microamps to trigger a GCFI regardless of the breaker rating.
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Re: Troubleshooting Tips Mini Blowing Fuses

Post by java man »

It's blown one fuse since I switched it over to 15A from 20 about 5 months ago. It happened while the machine was unattended.

One last item I haven't checked is the fuses themselves. After the first fuse blew some years ago, I saw they were $12 plus shipping, and thought that was ridiculous, so I checked at a local electronics store. Sure enough, they had plenty of 250V 20A slow fuses in stock. I bought a few ($1.20 each) and have been using them ever since.

But recently I noticed that the La Spaziale fuses for sale on espresso parts suppliers' sites look different from the generic glass body fuses I've been using. The La Spaziale fuse has a non-transparent body like the one on top. The one on the bottom is
like the ones I've been using.

Is it possible that the La Spaziale fuses are different?
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Java Man
(A.K.A. Espressopithecus)
Mini Vivaldi II
Baratza Sette 270Wi
Kinu Phoenix hand grinder
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