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Noobie dying here. Help Greatly Appreciated!!
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Discussions > Coffee > Home Roast > Noobie dying...  
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msmi
Senior Member


Joined: 29 Sep 2012
Posts: 8
Location: my
Expertise: Just starting

Posted Sun Jan 13, 2013, 4:45am
Subject: Re: Noobie dying here. Help Greatly Appreciated!!
 

Cheers. Appreciate the feedback!!

Power supply seems quite stable. Meter shows constant current just in excess of 230V. The nameplate indicates that it is 230V/50Hz/1500W.

The machine seems unable to ramp up the heat in a short period of time. Based on the on board readings, it takes about 3-4 mins to get to 160C (320F) and a further 5-7 minutes to go from 160-190 (320-374F). It always seems to stall at the 170-180C (340-360F) range. My thermocouple shows even lower temps early on until they converge only at the 175-180C range. It takes 10-12 minutes before coming close to 200C (392F).

This is the complete opposite to most of the posts from circa 2006 that the American model was burning too hot too fast, which gave rise to the "resistor" mods in the early European version, as I understand it.

My theory is possibly that the resistors were changed by the manufacturer in later models for the European markets which results in this slow burn although my understanding of the  mechanical/engineering components are non-existent.

I am currently contemplating 2 options. Either trying a 5 min warm up phase without any beans and roasting a full batch immediately after the cooling cycle has ended (which I know is not sanctioned by the manufacturer) OR opening up and checking the resistor to see if it is indeed higher than the 1ohm in the early models. If it is indeed closer to 2ohm, will changing the resistor to a lower capacity help me resolve the slow heat issue?

Advice much appreciated. Thanks.
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Snaxx
Senior Member


Joined: 11 Dec 2008
Posts: 174
Location: Northeast Michigan, LP
Expertise: I love coffee

Grinder: Capresso Infinity burr
Drip: Technivorm Moccamaster
Roaster: I Roast2
Posted Sun Jan 13, 2013, 9:43am
Subject: Re: Noobie dying here. Help Greatly Appreciated!!
 

I think you can rule out power issues if you see only a couple volts difference from static voltage on the circuit you're connecting to and voltage on that line when you're roasting.  

My theory is possibly that the resistors were changed by the manufacturer in later models for the European markets which results in this slow burn although my understanding of the  mechanical/engineering components are non-existent.

Here's a link to resistor mods in the Iroast:

"Okay, what is wrong here?"

I have two Iroast2, the one I use consistently was bought in 2008.  I found a second one to have as a spare or for parts last year, and that one was only used once to confirm that it worked.  The original one has no problem getting up to heat and it can follow the profile and finish up at 450 easy on the display.  The spare, using the same profile, didn't come up to heat as well or as high, so the roast time was extended for a couple extra minutes.  I found that link about the resistor mod a few weeks ago and compared both of the roasters to see if there was any difference in resistor values, which there wasn't.   I didn't try a different value resistor yet to see if that could have an effect on the roast temps of the spare, though I suspect it likely would.  If you do some experimenting and change out the resistor to a higher or lower value, a common half watt size would be adequate.  You might have to check the existing value with a meter since the color code on the installed resistor was illegible on mine.  

You mentioned a value of 1 ohm for a resistor value.  I think the value you will find will actually be around 1 K ohm.  Resistors are cheap, so you might want to pick up an assortment to play with, maybe from approximately 470 to 3.3K ohm @ 10%.  Somewhere in that selection, you should find one that is perfect.

I am currently contemplating 2 options. Either trying a 5 min warm up phase without any beans and roasting a full batch immediately after the cooling cycle has ended (which I know is not sanctioned by the manufacturer)

Iroast has all kinds of goofy warning messages for the user such as not roasting more than 7 times per week, or waiting two hours between roasting.  I'm sure these warnings are an attempt to protect Iroast from all kinds of failure warranty claims, though common sense would mean that once the roaster had cooled to room temp which would be in an hour or less, it would be fine to roast again.  I usually allow a half hour or so for cool time between consecutive roasts, though within 5 minutes of starting a roast, you're back up to these temps of 420 and above in the roaster, and that'll continue until cool mode.  I wouldn't worry about Iroast's warnings if you need to alter your roast sequence for heating the roaster before doing the roast.  If overheating should occur, there's an automatic reset overheat limit that opens to shut down the roaster, and that will happen to you if the fine mesh screens on the collector cap aren't kept clean from oil and residue.  I took my screens right out since the roaster runs much better without them.  The overheat protection is a dumb design, since if the roaster does overheat and shuts down, the fan also stops which is important to remain running to help with cooldown.  Go figure!!!

Ken
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msmi
Senior Member


Joined: 29 Sep 2012
Posts: 8
Location: my
Expertise: Just starting

Posted Sun Jan 13, 2013, 7:05pm
Subject: Re: Noobie dying here. Help Greatly Appreciated!!
 

Snaxx Said:

I think you can rule out power issues if you see only a couple volts difference from static voltage on the circuit you're connecting to and voltage on that line when you're roasting.  



Here's a link to resistor mods in the Iroast:

"Okay, what is wrong here?"

I have two Iroast2, the one I use consistently was bought in 2008.  I found a second one to have as a spare or for parts last year, and that one was only used once to confirm that it worked.  The original one has no problem getting up to heat and it can follow the profile and finish up at 450 easy on the display.  The spare, using the same profile, didn't come up to heat as well or as high, so the roast time was extended for a couple extra minutes.  I found that link about the resistor mod a few weeks ago and compared both of the roasters to see if there was any difference in resistor values, which there wasn't.   I didn't try a different value resistor yet to see if that could have an effect on the roast temps of the spare, though I suspect it likely would.  If you do some experimenting and change out the resistor to a higher or lower value, a common half watt size would be adequate.  You might have to check the existing value with a meter since the color code on the installed resistor was illegible on mine.  

You mentioned a value of 1 ohm for a resistor value.  I think the value you will find will actually be around 1 K ohm.  Resistors are cheap, so you might want to pick up an assortment to play with, maybe from approximately 470 to 3.3K ohm @ 10%.  Somewhere in that selection, you should find one that is perfect.



Iroast has all kinds of goofy warning messages for the user such as not roasting more than 7 times per week, or waiting two hours between roasting.  I'm sure these warnings are an attempt to protect Iroast from all kinds of failure warranty claims, though common sense would mean that once the roaster had cooled to room temp which would be in an hour or less, it would be fine to roast again.  I usually allow a half hour or so for cool time between consecutive roasts, though within 5 minutes of starting a roast, you're back up to these temps of 420 and above in the roaster, and that'll continue until cool mode.  I wouldn't worry about Iroast's warnings if you need to alter your roast sequence for heating the roaster before doing the roast.  If overheating should occur, there's an automatic reset overheat limit that opens to shut down the roaster, and that will happen to you if the fine mesh screens on the collector cap aren't kept clean from oil and residue.  I took my screens right out since the roaster runs much better without them.  The overheat protection is a dumb design, since if the roaster does overheat and shuts down, the fan also stops which is important to remain running to help with cooldown.  Go figure!!!

Ken

Posted January 13, 2013 link

Thank you Ken. Sincerely appreciate you taking time to respond. Although new to this, it is nevertheless frustrating not being able to get a cup of half decent coffee time and time again. Any advice is gratefully received & shall certainly be followed. Will keep going!!

I have still not decided on which route to take. Pre-heating seems easier to execute but I have a feeling the more difficult "resistor mod" will be much more effective. Fingers crossed & thanks again!!

Moe
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