My Great-Grandmother's Vintage Chicobar Espresso Machine - Page 11

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AGordo (original poster)

#101: Post by AGordo (original poster) »

drgary wrote:That's a lot of scale, but it looks like it's proceeding well. Immersing non-electric rusted parts in Evapo-Rust works well. It dissolves away rust and leaves the rest alone.

Trying to be as methodical as I can be. Will be going after the scale shortly. I ordered some Evapo-Rust, so hopefully next week I can start restoring all the metal parts. You mentioned immersing the non-eletric rusted parts, does that mean I should not immerse the heating element as well? And if not, then what would you recommend is the best way to clean the rust off the heating element? White vinegar? And since nothing is hooked up, can I immerse the entire part, or just the element?
drgary wrote:That much scale may have overheated the heating element and damaged it. A simple multimeter may not tell the whole story. An electrician would have a more expensive device that can better test it. The name of it currently escapes me because I don't have one. Someone else watching this thread will be able to tell you.
Hmm, what kinda of measurement would I be looking for to give me a better idea if it was damaged? I may have access to some more test equipment, but don't know what I'd be looking for. Can I test it outside of the boiler by hooking up some electrical and seeing if it heats up? Or is that potentially damaging / not a good indication?

Thanks for the help!

AGordo (original poster)

#102: Post by AGordo (original poster) »

grog wrote:A megger is the next step up from a multimeter. The start at several hundred bucks, but as Gary says, provide much more accurate info.
I'm not sure I have access to a megger, but is there anything else I can use / what measurement am I looking for?

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#103: Post by billt »

There's not much that can go wrong with a heater; the element can change resistance - usually goes open circuit so it won't work at all. Can go low resistance, but it won't last long!

The other thing is that the insulation fails. You can get an idea of the insulation resistance with the resistance range of a DMM, should be over a megohm. What a megger does is check the insulation resistance with a high voltage applied, as insulation can sometimes measure OK with a low voltage but breakdown with a high voltage. I'd just do simple resistance checks with a DMM. If it's OK I'd power it up once the machine has been reassembled and filled with water. If there's a voltage dependent insulation issue it will trip the RCD (GFCI). Definitely not worth buying a megger for this job, it would be much cheaper just to replace the heating element, assuming that you can get one.

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Team HB

#104: Post by drgary »

Good answer! These days a vintage heating element can be rebuilt. Let's hope that isn't necessary.

What I WOULD do for a good cup of coffee!

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#105: Post by cuppajoe »

I test elements individually before reassembling the machine, as getting the thing back together to find the element is NG is frustrating. And as a lot of these vintage machines are not grounded at the plug and made before the advent of GFIs, it is a good idea to correct that by replacing the cord.

I have had several machines where the element heated fine but would trip the GFI, so made up a test rig for testing elements for heating and ground problems. This is simply a grounded appliance cord with the insulation removed at the ends of the leads(wires) to facilitate attaching to the element.. The two power leads are attached to the taps on the element and the cord is plugged into a power strip. The element is placed in a bowl of water for the test and then the power strip is turned on. If the element heats as it should, I then touch the ground lead from the cord to the metal housing of the element. If it trips the GFI then the internal element insulation has gotten damp or has broken down. If the former, it is possible to repair by following procedures as outlined on various threads and OE's web site. If the latter, it's toast.

Just remember you are fooling with high voltage and water, which demands full attention and respect.
David - LMWDP 448

My coffee wasn't strong enough to defend itself - Tom Waits