HomeRoast Digest


Topic: I-Roast2 malfunctions (13 msgs / 299 lines)
1) From: Starfinder Stanley
Well, here I am at the inlaws' in Florida, trying to troubleshoot the
malfunctioning iRoast2 we gave them for XMas (from SM's) 2 years ago.  The
first one fried itself in about a year and was replaced by the company with
another base unit, which didn't work properly from the get-go....
Unfortunately, around the same time her mom was diagnosed with cancer, and
so coffee roasting was relegated to the back burner for a while.
Now that things are settling down again, she's started trying to roast
again, and the malfunctioning unit is frustrating her.  It fires up fine,
but gets partway through a roast and then just shuts off ---I've seen it do
it 3 minutes in, or 7 minutes in, both times on the same profile from a cold
start.  When it shuts off, it just resets to ready-to-roast, like it was
just plugged in.  You can start it roasting again (and I did, since I was
not even to first crack), and it might run for 15 seconds or through to the
end of the roast.
I started off by reducing the amount of beans to 1/2 a cup.  No
improvement.  I thought it might be restricted airflow, since the first unit
died and the second wasn't working right out of the box, so I cleaned all
the screens thoroughly.  No improvement.  I removed the lower air intake
screen to reduce preload.  Seemed to run longer, but still didn't make it
through a roast, and the time to shutdown is so variable I can't say that it
helped any.  I took the roaster outside and ran it without the chaff lid on,
to minimize afterload backpressure.  Still took 3 resets to finish the
roast.  I angled the roaster to take some more pressure off the fan.  No
improvement.
Next I'll see if it runs through the whole cycle without beans, I guess....
Anybody have any ideas, suggestions?
...Starfinder
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2) From: Allon Stern
On Dec 26, 2009, at 1:01 PM, Starfinder Stanley wrote:
<Snip>
Well, it sounds to me like the thermal cutout switch is opening. Most home appliances that generate heat have a thermal cutout switch to prevent runaway operation in the case of a malfunction, which might lead to a fire or catastrophic failure.
After two years, I'll bet theres a lot of crud built up inside the unit.
Here's some pictures of a unit being taken apart. This one had an open coil in the heating section; I have yet to get around to repairing it.http://www.radioactive.org/iRoast2%20Teardown/Photos.htmlThese photos concentrate on the electronics, not on the fan and heater. The fan is a simple shaded pole motor, which comes apart pretty easily, and can be cleaned. The impeller can also be removed and cleaned. The crud build-up inside the fan assembly may cut the airflow in a way that external efforts will not address. If you are not comfortable taking the unit apart, do not. You can get hurt, or cause a fire. But if you are comfortable with fiddly electronics bits, I suggest a complete teardown may be in order if you want to rescue this machine.
I make take a few more pictures of the fan assembly, if you want to see it. In fact, no. I will go take pictures now. Back in a few :)
-
allon
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3) From: Starfinder Stanley
Thanks for taking the pics, Allon!
I don't think there's a lot of crud in the machine because the base isn't 2
years old --- it's a replacement unit that has seen pretty light use for
about half of the last year (largely because it wasn't working right to
begin with).  However, it was working better than the base it replaced,
which wasn't working at all ----this one just had to be restarted 3 or 4
times to complete a roast.  Having done the routine myself about 5 times
this week, I can attest that as a roasting method, it's a pain in the butt.
So my wife's mom wasn't messing with it, plus she was dealing with health
issues for about 6 months and not really into roasting for a while.
I also don't think that the unit is shutting down in response to actual
overheating, since it just resets itself and will start right up again, at
which point it might run through the rest of the roast or only for 10
seconds (no discernible way to predict which).  Don't most thermal cutout
switches prevent restarting until the thing cools down?
All of which leads me to think that there is a faulty component causing the
unit to shut down inappropriately; the thermal cutout switch sounds like a
promising suspect.  The mother in law said she fell into the iRoast customer
service purgatory when she last called and gave up, as it was quite an
ordeal getting anywhere the last time she'd dealt with them.
I wonder how hard it is to get a replacement thermal cutout switch?
On Sat, Dec 26, 2009 at 7:27 PM, Allon Stern  wrote:
<Snip>
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4) From: Doug Hoople
Hi Starfinder,
Could be there's a really simple answer. I used to have problems, too, that
answered your description.
Turns out that it was simply the pressure switch between the upper and lower
units. It was a little bit loose, enough so that the iR2 would cycle to cool
partway through the cycle.
My fix was very crude. I simply folded a bit of copper foil (from a ham
radio ground plane strip) over the tab that actuates the switch. A simple
spacer, actually. It added just enough downward pressure to prevent the
problem from ever recurring.
Before I found this simple fix, I was very frustrated and wanted to return
the unit, but was worried that, with the intermittent nature of the problem,
I wouldn't be taken seriously by the manufacturer. In the end, it didn't
matter. The iR2 has worked beautifully ever since.
With any luck, the problem you're working will turn out to be similar.
Good luck, Starfinder, and let us know what it turns out to be!
Thanks.
Doug
On Sun, Dec 27, 2009 at 6:50 PM, Starfinder Stanley wrote:
<Snip>
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5) From: Allon Stern
On Dec 27, 2009, at 12:50 AM, Starfinder Stanley   
wrote:
<Snip>
It could be a loose connector.or a defective control board. The power  
connection to the controller is a two pin connector. Or it could be  
the power regulator which provides control logic power (i dont think  
this is in my picture set either). If you feel comfortable working in  
electronics, I can send you my spare controller board and power  
regulator.
As for the thermal cutout, youd have to read the markings on it to  
determine the ratings, then order another. I may look it up later  
today when I'm in front of my real computer. As noted, there are  
multiple things that could be wrong. I'd start by removing and  
reseating any connectors. Only if it still failed would I start  
replacing components.
-
allon
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6) From: Mike Davis
Erratic intermittant electrical malfunctions almost always point to a weak solder joint or connection.  Many of us have used the iRoast for years with no problems.  Clean the unit after each batch avoid letting chaff or dust into the base unit at the top of bottom when cleaning.  Check the easy stuff first like the connections before fixing things that aren't likely to be broken.
And let us know what you found.
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7) From: Starfinder Stanley
Well, I took it apart as best I could here (armed with a phillips driver and
little else), checked all the connections I could, unseated and reseated
everything, didn't see any obviously bad solder joints, reassembled it, and,
of the 4 possible outcomes.... no change whatsoever.  I can exactly
replicate what it is doing by unplugging and replugging the cord, or by
toggling the switch on a power strip off/on, in the middle of a roast.  It
seems that it runs for about 4-6 minutes when cold, then shuts off,
(restart) then will run usually about 30-40 seconds before shutting down
again, (restart) 30-40 seconds and shuts down, restart.... etc until
sufficient roast prompts the cool button.  Once in cool mode it runs without
hiccup until the 3 minute cycle is over.
So it seems like something is interrupting the power supply when it is hot.
I'm leaving tomorrow; if she decides to replace the unit, I'll have her send
me the old base and see if I can figure out what is wrong with it.
On Sun, Dec 27, 2009 at 12:43 PM, Mike Davis  wrote:
<Snip>
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8) From: Starfinder Stanley
Actually, I didn't remove the controller board to check the connections and
solder points on it, so I may have missed something ---I had a limited
amount of time and wanted to make sure I at least returned it to its
semifunctional state....  I just checked the relay board/fan/heating coil
connections....  Maybe I should have wrested the controller out, it was just
another layer of disassembly....
On Mon, Dec 28, 2009 at 2:10 PM, Starfinder Stanley wrote:
<Snip>
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9) From: Dave McCracken
On Saturday 26 December 2009, you wrote:
<Snip>
My last iRoast developed exactly this problem after I'd owned it for about 2 
years.  I'm entirely convinced it was the thermal sensor that flaked out.  It 
would just stop at some random point in the roast and would allow me to start 
a new roast immediately.
The reason I'm convinced it was the thermal sensor is when I'd push the button 
to get a temperature reading, I'd see it occasionally jump from its true 
temperature to some random value 50 degrees or more higher, then immediately 
drop back.  My assumption is that at some point the false high reading would 
be high enough to trigger the overheat shutdown.  And since it was so 
transient it would immediately be ready to start another roast.  You might try 
checking the temperature readings on yours to see if you get the same 
transient high temperature anomalies.
Rather than spend a lot of time and effort tracking it down I took the easy 
way out and got a new roaster (a Gene Cafe this time).
Dave McCracken
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10) From: Doug Hoople
Hi Starfinder,
When the unit trips, what's the symptom? Hard stop, or cooling cycle?
Doug
On Mon, Dec 28, 2009 at 4:00 PM, Starfinder Stanley wrote:
<Snip>
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11) From: Allon Stern
On Dec 28, 2009, at 5:10 PM, Starfinder Stanley   
wrote:
<Snip>
Given the failure mode, I'm guessing it's probably the thermal cutout,  
or the spade lug connections that lead to it.
-
allon
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12) From: Starfinder Stanley
It just turns the fan/heater off and resets the LCD readout to 0, exactly as
it would if you unplugged it and replugged it in the middle of a roast.
On Mon, Dec 28, 2009 at 6:38 PM, Doug Hoople  wrote:
<Snip>
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13) From: Doug Hoople
"It just turns the fan/heater off and resets the LCD readout to 0, exactly
as
it would if you unplugged it and replugged it in the middle of a roast."
OK, then, that definitely rules out the switch that senses that the roasting
chamber is in place and properly seated. When that slips loose mid-roast, it
simply enters the cooling phase.
Sorry for the interruption... carry on where you left off.
Doug
On Mon, Dec 28, 2009 at 9:46 PM, Starfinder Stanley wrote:
<Snip>
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