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Help w/ Giotto..Heard a 'Pop' then fireworks smell - Page 2

Postby adimperial on Sun Feb 14, 2010 2:11 pm

Looking for multimeters online, Radio Shack has a few.. don't know which to get.. http://www.radioshack.com/search/index....meter&sr=1
Are the cheap < $20 ones ok? Thanks
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Postby boyscout on Sun Feb 14, 2010 3:29 pm

A.D., you're kind of asking the wrong guy... I'm just a hobbyist and I have a top-of-the-line DMM. I have a thing for excellent tools.

But if I had to buy the least-expensive practical DMM I could buy, I might buy this one:

http://www.multimeterwarehouse.com/m838f.htm

The reason I selected it is that it apparently offers temperature reading as well, which as an espresso machine owner you might find useful. Disclaimer, though, I have just looked very quickly at that site and this device. They do have many, many other products there, and moving up the ladder gets you features of convenience and capability you might possibly want some day, for only $20-$30 more.

EDIT: The least-expensive Radio Shack models are analog meters that aren't usually as fast-acting, versatile, or long-term reliable as digitals. If you want to buy from them for some reason, this might be the best bet but it has no temperature capability:

http://www.radioshack.com/product/index...Id=2103176

But, as I said, I'm not the guy you should be asking for advice about inexpensive tools. :D I could quickly take you into the $150 range, or even the $800 range like mine, but the function you need for this test A.D. is about the most common and most basic function of a DMM. You could buy or borrow pretty much ANY working DMM and be able to test resistance with it.

Good luck.
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Postby shadowfax on Sun Feb 14, 2010 7:29 pm

Here's a quick post for David (adimperial)...

David came by my place today with the Giotto and we checked it out. I checked the heater and he was thankfully safe (11Ω, I assume that's 10A/1100W). The thermal fuse had continuity, too.

I looked the machine over and it seemed aged but fine, so I unhooked the wire to the thermal fuse to prevent the heater from coming on and plugged in the machine. So far so good. Upon flipping the switch we were confronted with a small flare-up and a modicum of electrical smoke from beneath the boiler. I immediately pulled the plug and we had a look. It turned out that the boiler fill solenoid coil had fried quite dramatically before our eyes. One of the spade leads coming out of it had melted off and separated, and the coil itself seemed almost fused to the shaft when I tried to pull it off, a real stinky black mess.

The Giotto has an amazingly cheaply designed arrangement in the respect of the autofill. That solenoid coil is FACE UP (as in the side with the leads is up) and right beneath the boiler and the reservoir. If any water falls down into the machine it can easily fall on to the solenoid and make for a short circuit. The darn coil has a tapped metal hole on the lead face that is designed to allow a sealed plug manifold to attach and screw down, rather than the 3 separate semi-exposed plugs that are used on the Giotto, and this would have been an ideal solution for a coil that's oriented and positioned the way this one is. Anyway, there didn't seem to be any water down below when we turned the machine on, so I assume the damage had already been done and this was the final stages of the part failing. I've never seen this type of failure before or even read about it, so this was indeed quite interesting for me.

I've advised David that we can try getting a new fill solenoid coil (I think these should be ~$30) and installing it, and that may fix things up just fine (or may lead to us finding more problems!), but the machine has some other issues (bends in the frame from shipping) that probably ought to be professionally repaired. I think he's going to go that route, but obviously he can clear that up himself if he prefers.
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Postby another_jim on Sun Feb 14, 2010 8:53 pm

Thanks for the clarification. No wonder I thought this was a twilight zone machine. As an oops with a variac once showed me, short circuiting an electric coil will create some lovely smolders and pops; but who would have thought it could come from beneath an espresso boiler?

Mostly, on the espresso machines with horizontal boilers, there are components beneath the boiler. But a metal canopy should be installed to shield them from leaks.
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