Would you be able to share a photo of what your setup looks like? 20c drop is significant and I want to see if I can get that. TIA!!
I’m in the 81 club too
Thanks @duckduckco I’ll try this but not sure if that cooling fan wire is going to be long enough since I put a vent hose at the end to direct the exhaust closer to my range vent hood. Currently my setup is the opposite as yours with the fan on the other wise. I’ll try next weekend when I plan to roast and see if it keeps the IGBT temp as low as yours. Or I might try the placement right under as @krame has it, have to see how the spacing works on top of my stove.
BTW, did you craft that bean deflector yourself?
I think as long as as the fan blows over the PCB you’ll are good. I had it on the same side as the power cord. Someone mentioned that you should place it on the other side of the power cable or underneath too.
Bean deflector is from Cafe Natureve $95 ish CAD shipped for me at the time. Well worth it.
I just added a 120mm x 120mm x 25mm(thick) 12volt muffin fan to the PCB cover. It looks clean, but I haven’t tried it yet. The holes in the cover reduce the air flow from the fan quite a bit. If this proves out to be effective, I may go back and modify the PCB cover by making a cutout where the fan is.
~3.25 inches from the Table top to the bottom aof the fan
Here is a link to the fan that I bought from Amazon, the variable speed control is included (~$19.00 USD):
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Let us know how this performs esp if you also roast 900g to 1kg batches. I would like to know for future considerations 
Edit: Question… Is the direction drawing air out (i.e. towards the table)?
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Air flow is towards the circuit board. Away from the table.
I did a 500g Honduras Decaf, dropped at 425F for my spousal unit this morning and the PCB temp never went above 61c. I didn’t use P9 for this profile. I don’t know what it is without the fan on, I never looked before.
I’ll be doing an 800g Ethiopian in a day or two. I’ll report back.
I modified the PCB cover (cut a big hole) so that there is no interference with the airflow from the new fan.
I ran a 1000g roast of some Ethiopian beans that I like.
The PCB temperature atarted at 29.5C before HT and after 536F HT the PCB temperature was 58C.
The highest the PCB temperature reached in 13 minutes during the actual roast was 68.8C.
I was having problems before with v591 F/W trying to run 800g roasts. The Bullet would drop the power to P0.
I am running the latest v602 firmware. I did experience a new problem for me. I was running an old roast as a playback and the bullet ignored the first parameter changes for Power and Fan after HT. Once I manually changed them to the settings that I wanted, then they would follow the playback. “No good deed…”
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Coincidentally I’ve noticed the same thing lately. Maybe 2-3 roast last week skipped the initial setting. I was doing playback too which really shouldn’t be an issue.
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I continue to get the IGBT warning on my bullet v2. 453g roasts at p7 and p6 keep it at 95 - 96C, on the first roast.
I’m going to look into fan solutions, thanks for the ideas! It is certainly a big bummer that a machine this expensive needs a fix like this. I hope they add a PCB fan to future models.
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If you get overheating on P7 then please contact support and have them look at the logs.
The 110V Bullet is running right on the limit of what is feasible on 110V. To keep it cool it should be placed in a well ventilated space. However, if you get a warning on your very first roast, and not using full power, then there might be a problem with your board.
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Just need to figure out a glycol chiller setup here.
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The bean cooler fan should point away from the belly of the roast as well. This helped me a lot.
I was sent a replacement induction fan with slightly higher amps. I have done one roast after replacing the fan today, and it stayed in the high (but acceptable) range. I think it got up to 87.
The new fan is significantly louder than the previous fan, but it’s quieter and less annoying to set up than the external fan I had been using. I have not tried a roast that sits at P9 yet, or back to back roasts in the middle of the day. I’ll report back when I have more data.
I shot a video of the replacement procedure, so if anyone else has to do this, it might be helpful.
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Same solution here. Small fan underneath and the cooling tray venting to the side and not underneath the roaster. Big roasts in the summer were giving me the yellow warning.
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I use the under belly fan for every roast.
Something else that I would try first is aiming a small fan at the bottom right side of the control panel. That is where the air inlet is for the IGBT fan and there is a sensor in there.
After aiming a small fan at the grill opening, the temperature will drop 10-20 degrees within a few minutes. This was suggested to me by Matt from Aillio.
Cheers.