Why my iRoast2 is Half Baked (and can it be fixed?)

[hazbean]

Re: Why my iRoast2 is Half Baked (and can it be fixed?)

Thanks for the comments. My assessment was close to that of
JavaB and AM, but Ill have a close look when I get a chance to see if
Erics idea might work. May have to pull apart the element support to
do it, which looks messy, but should be able to work something out.
Luckily there is no great urgency.

[Coffeengineer]

Re: Why my iRoast2 is Half Baked (and can it be fixed?)

Looks like an easy repair to me... just put an M3 STEEL screw thru the mica at the bottom of the pic (for support) and tightly clamp the nichrome ends between lock nuts.

Eric

[JavaB]

Re: Why my iRoast2 is Half Baked (and can it be fixed?)

Hazbean,

That wire would be a variety of nichrome... and the only way to get an electrical connection to it is either use:

Screw terminals,
Crimp connectors
Welded joint....

So.........Repairing whats left of the element isnt really practical....

Basically the element would need to be replaced with an identical wire of the same ohms/meter resistance rating..... and diameter alone is not a good indication of its resistance characteristics.... and there are differences in the composition of the wire for different purposes.....

So, whilst anything is possible...... it wont be easy to find a replacement -- other than handing over hard earned for a new one....

[hazbean]

A year or so ago, shortly after the GeneCafe arrived, I was trying to
do some comparative roasting with the iR2, when part way through
temp readings just plummeted and wouldnt come up again. Clearly
the heating element was only partly working, so beans would try
to roast but come out baked.

So I put it in a box (with a few expletives) and forgot about it.
But Ive been recently prompted to have another look, partly by a
conversation about profiles, and partly by finding this story

 http://coffeegeek.com/forums/coffee/homeroast/413807

of a true hero who actually fixed his iRoast.

As weve recently acquired a power meter, I started by running it
on a 15 minute max temp profile (no beans) and noting watts;
consumption was an almost unvarying 905 to 915 watts for the
whole period i.e. running flat out a long way below normal power.

Then I pulled it apart, starting with the notes in the post above.
The top and the base come apart easily, revealing a unit with fan
motor on one side, and heating elements and thermistor on the
other. This has about eight screws around the perimeter, but
comes apart fairly easily. Then we find a heating element
"module" with two wire heating coils in it (fairly loosely
coiled). These are of slightly different length. In the outer
one, I found a point where two loops had fused together,
breaking the circuit, and giving about half heating capacity.

Ive put several pictures of the exercise here:

 http://picasaweb.google.com.au/haazbean/IRoastDissection

and below is one showing the failure.



Just wondering if / how this could be repaired? I guess trying to
find an equivalent coil and working it in.

Or maybe snipping all the wires to to the top, installing a new
heating element, and running it an the fan to some external
controllers with a PID. A PID controlled "super popper" ????