If you watch the whole video (spoiler alert!), at the end he kills the RFI
by shunting the AC with some capacitors and increasing the value of a cap
coupling the AC ground with the DC ground on the other side of the SMPS. He
mentioned that he has about three of these coffee machines and only one of
them is misbehaving.
However the troubleshooting is less satisfactory than is usual for Paul
Carlson, VE7ZWZ (he is usually restoring antique radios). Essentially the
problem is (spoiler alert!) in the microcontroller firmware which appears
to have flipped a bit somewhere in the motor control/PWM code path.
On Fri, Jan 14, 2022 at 6:22 AM Hare, Ed, W1RFI <w1rfi@arrl.org> wrote:
> This is very interesting. I do note that the unit in question is
> defective, with a motor that seems to be running very slowly. This could
> be the reason for the RFI problem. ARRL has zero reports of KRFI (Keurig
> RFI), but I am sure many a ham has a Keurig. If any of you do experience
> this problem, send an email to rfi@arrl.org with the details.
>
> It is worth noting that under FCC rules, this would be classified as an
> appliance (used in heating, cooling, cleaning or the preparation of food).
> As such, it is categorically exempt from the specific emissions limits that
> apply to other unintentional radiators. Appliances are subject only to the
> requirement that the operator use them in a way that does not cause harmful
> interference.
>
> Ed, W1RFI
>
> ------------------------------
> *From:* RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of
> Charles Coldwell <coldwell@gmail.com>
> *Sent:* Friday, January 14, 2022 1:24 AM
> *To:* rfi@contesting.com <rfi@contesting.com>
> *Subject:* [RFI] Mr. Carlson's Lab: coffee maker RFI
>
> Pretty interesting
>
> https://youtu.be/f3dGStQuI7c <https://youtu.be/f3dGStQuI7c>
>
> --
> Charles M. Coldwell, W1CMC
> "Turn on, log in, tune out"
> Belmont, Massachusetts, New England (FN42jj)
>
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
--
Charles M. Coldwell, W1CMC
Belmont, Massachusetts, New England
"Turn on, log in, tune out"
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