Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old November 25th 14, 06:23 AM posted to sci.electronics.repair
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Default Fan causing MW RFI

Jeff Layman wrote:
I have a 6-months old Fantasia ceiling fan (mains powered, with 6-speed
reversible dc motor) which is causing a lot of interference on MW. FM is
not affected. The interference is there on forward or reverse rotation,
worsens as the speed is increased,, and appears on portable as well as
mains-powered radios.

I can return it to the supplier for replacement or refund, but it is a
bit of a rigmarole to remove and refit. All the electronics are sealed
in, and the only accessible wiring is to the mains connector. Is there
any point in trying some sort of screening or RFI suppression on the
mains wiring before I take it down?



My furnace fan creates so much noise, I can't do much with it on. It's
variable speed, and has peak noise at max speed. I tried some filtering on
ac and thermostat, but it's a big problem.

Greg

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Old November 25th 14, 04:59 PM posted to sci.electronics.repair
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Default Fan causing MW RFI

On 25/11/2014 02:10, Phil Allison wrote:

Jeff Layman wrote:

I have a 6-months old Fantasia ceiling fan (mains powered, with
6-speed reversible dc motor) which is causing a lot of interference
on MW. FM is not affected. The interference is there on forward or
reverse rotation, worsens as the speed is increased,, and appears
on portable as well as mains-powered radios.

I can return it to the supplier for replacement or refund, but it
is a bit of a rigmarole to remove and refit. All the electronics
are sealed in, and the only accessible wiring is to the mains
connector. Is there any point in trying some sort of screening or
RFI suppression on the mains wiring before I take it down?



** The instructions say all units must be earthed - is yours?


I hope so! It was installed by a pro electrician and I have a NICEIC
certificate which says so (http://niceic.com/). But I'll check it anyway.

You could try a suppression cap across the line( active to neutral)
at the terminal block - close as possible to the fan itself. A class
X1 or X2 film cap of about 470nF is a good place to start. But I bet
there is one inside the fan already.


The only thing I can get in the next day or so is this delta suppression
filter:
http://www.maplin.co.uk/p/delta-supp...n-filter-rg21x

I expect the fan motor is a BLDC type, possibly operating at mains
voltage, and the pitch of the noise on AM would vary with its speed.


Guess so. The fan often turns in the reverse direction for a second or
so when switched on, then corrects itself.

BTW:

Are you living far from AM transmission sites - say than 50 kms ??


No. The 999kHz local radio transmitter (1kW) is about 15 km away..

BTW 2:

Are you living in a metal clad ( aluminium sided ) building ?


The fan is in a new metal-framed conservatory. The mains-powered MW
receiver in the conservatory is completely swamped by the interference.
But the portable radio is outside, maybe 6 metres from the fan, and that
has the interference superimposed on the station I am listening to. It's
no doubt attenuating the interference, but not enough

Either of the above means the AM signals inside your home will be
very weak.


..... Phil


Thanks for the info and suggestions.

--

Jeff
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Old November 25th 14, 08:26 PM posted to sci.electronics.repair
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Default Fan causing MW RFI

On 24/11/2014 20:33, Tom Miller wrote:

"Jeff Layman" wrote in message
...
I have a 6-months old Fantasia ceiling fan (mains powered, with 6-speed
reversible dc motor) which is causing a lot of interference on MW. FM is
not affected. The interference is there on forward or reverse rotation,
worsens as the speed is increased,, and appears on portable as well as
mains-powered radios.

I can return it to the supplier for replacement or refund, but it is a bit
of a rigmarole to remove and refit. All the electronics are sealed in, and
the only accessible wiring is to the mains connector. Is there any point
in trying some sort of screening or RFI suppression on the mains wiring
before I take it down?

--

Jeff


You might try winding the AC lines through a ferrite RFI core like the ones
found on switching power modules. Some can be clamped around the wires. You
will want to get all three leads through the core, L, N, and Ground. Maybe
even do a couple of turns if the core is large enough.


I'll try that. Thanks.

--

Jeff
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Old November 26th 14, 02:22 AM posted to sci.electronics.repair
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Default Fan causing MW RFI

Jeff Layman wrote:


The only thing I can get in the next day or so is this delta suppression
filter:
http://www.maplin.co.uk/p/delta-supp...n-filter-rg21x


** That should do OK.



I expect the fan motor is a BLDC type, possibly operating at mains
voltage, and the pitch of the noise on AM would vary with its speed.


Guess so. The fan often turns in the reverse direction for a second or
so when switched on, then corrects itself.


** Really ?

What makes you sure it is a DC motor ?

DBDC motors are really AC motors with in-built electronic drives.

Motors that power ceiling fans are normally multi-pole induction types - fully reversible.



No. The 999kHz local radio transmitter (1kW) is about 15 km away..


** So the available signal is weak.



The fan is in a new metal-framed conservatory.


** So the signal inside is very weak.


.... Phil
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Old November 26th 14, 09:17 AM posted to sci.electronics.repair
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Default Fan causing MW RFI

On 26/11/2014 01:22, Phil Allison wrote:
Jeff Layman wrote:

I expect the fan motor is a BLDC type, possibly operating at mains
voltage, and the pitch of the noise on AM would vary with its speed.


Guess so. The fan often turns in the reverse direction for a second or
so when switched on, then corrects itself.


** Really ?

What makes you sure it is a DC motor ?


See under "Energy efficiency" on page 3 he
http://www.fantasiaceilingfans.com/c...chure-2014.pdf

Also see top of page 2 and section 3 on page 10 he
http://www.fantasiaceilingfans.com/c...tau-manual.pdf

DBDC motors are really AC motors with in-built electronic drives.

Motors that power ceiling fans are normally multi-pole induction types - fully reversible.


So it could be that the manufacturer calling it a "DC motor" is being a
bit flexible with the definition?

No. The 999kHz local radio transmitter (1kW) is about 15 km away..


** So the available signal is weak.


Fairly so, but reception is quite acceptable when the fan is off.

The fan is in a new metal-framed conservatory.


** So the signal inside is very weak.


Indeed, even with a loop aerial connected.

--

Jeff


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Old November 26th 14, 12:15 PM posted to sci.electronics.repair
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Default Fan causing MW RFI

Jeff Layman wrote:

** Really ?
What makes you sure it is a DC motor ?


See under "Energy efficiency" on page 3 he
http://www.fantasiaceilingfans.com/c...chure-2014.pdf


** So my original hunch was correct.

Some modern ceiling fans use low voltage( ie 24V) BLDC motors operating from a SMPS - all crammed into the same housing.

Why one would run in the wrong direction before correcting itself is a tad mysterious.





No. The 999kHz local radio transmitter (1kW) is about 15 km away..


** So the available signal is weak.


Fairly so, but reception is quite acceptable when the fan is off.



** You have missed the point.


The fan is in a new metal-framed conservatory.


** So the signal inside is very weak.


Indeed, even with a loop aerial connected.



** Assuming the fan has not developed a fault since you installed it, the RFI you are hearing may well be within legal limits for such appliances.

The AM and HF (short wave) bands do not enjoy the same regulatory protection as FM and TV reception does - so things like SMPSs and motor drives are permitted interfere somewhat with AM receivers in the same premises.

Having only weak signals available in the vicinity makes it so much worse.

Is the fan motor in a plastic enclosure ?

A grounded, metal one would be far better at supressing AM band noise.


..... Phil






--

Jeff


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Old November 27th 14, 05:48 PM posted to sci.electronics.repair
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Default Fan causing MW RFI

On 26/11/2014 11:15, Phil Allison wrote:
Jeff Layman wrote:

Some modern ceiling fans use low voltage( ie 24V) BLDC motors
operating from a SMPS - all crammed into the same housing.

Why one would run in the wrong direction before correcting itself is
a tad mysterious.


Puzzled me too so I Googled for the explanation. I have no idea if it is
accurate, but see the final paragraph in this section:
https://en.wikipedia.org/wiki/Brushl...lementat ions

No. The 999kHz local radio transmitter (1kW) is about 15 km
away..

** So the available signal is weak.


Fairly so, but reception is quite acceptable when the fan is off.



** You have missed the point.


The fan is in a new metal-framed conservatory.

** So the signal inside is very weak.


Indeed, even with a loop aerial connected.



** Assuming the fan has not developed a fault since you installed it,
the RFI you are hearing may well be within legal limits for such
appliances.

The AM and HF (short wave) bands do not enjoy the same regulatory
protection as FM and TV reception does - so things like SMPSs and
motor drives are permitted interfere somewhat with AM receivers in
the same premises.


I don't know if it is. It should fall within Directive 2004/108/EC, but
it isn't CE marked, and compliance with that Directive isn't mentioned
in the manual.

Having only weak signals available in the vicinity makes it so much
worse.

Is the fan motor in a plastic enclosure ?

A grounded, metal one would be far better at supressing AM band
noise.


I think it is plastic.

Anyway, I was able to try a few things today, and the interference has
been reduced to almost zero. Firstly, the earth appears OK. Just in
case, I connected another earth lead to a known good earth, but it made
no difference. Next I fitted the delta filter, which suppressed the
interference almost completely - result! Next I pulled the power
connector plug apart and wound the lead a couple of times through a
large ferrite ring (the only one I could get easily), and that cut out
almost completely what little noise was left. There is slight
interference when the fan is running at full speed, but I never use it
at that. speed.

So that's a good result without dismantling and returning the fan - thanks.

But here's something odd I found on the way. I got the MW on the
mains-wired radio in the conservatory working pretty well with only a
metre of wire connected as an aerial. It wasn't bad, but a bit quiet.
Well, the signal was weak. Fair enough in the metal conservatory. But
that was with the fan power connector unplugged (for fitting the ferrite
ring). As soon as put the power connector back together, so I could run
the fan (this is with the main power still disconnected at the wall
switch), the radio reception improved tremendously - loud and clear!
When I pulled the connector it went back to fairly quiet again. Weird -
something is acting as an aerial, but how?

--

Jeff
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Old November 28th 14, 09:08 AM posted to sci.electronics.repair
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Default Fan causing MW RFI

On Monday, November 24, 2014 10:15:12 AM UTC-6, N_Cook wrote:
On 24/11/2014 15:41, Jeff Layman wrote:
On 24/11/2014 14:01, N_Cook wrote:
On 24/11/2014 12:57, Jeff Layman wrote:
I have a 6-months old Fantasia ceiling fan (mains powered, with 6-speed
reversible dc motor) which is causing a lot of interference on MW. FM
is not affected. The interference is there on forward or reverse
rotation, worsens as the speed is increased,, and appears on portable as
well as mains-powered radios.

I can return it to the supplier for replacement or refund, but it is a
bit of a rigmarole to remove and refit. All the electronics are sealed
in, and the only accessible wiring is to the mains connector. Is there
any point in trying some sort of screening or RFI suppression on the
mains wiring before I take it down?


I find it amazing you can listen to MW/AM in a "modern" house with all
that electronic smog and EMI and RFI everywhere


Just about everything has a SMPS these days, and often some digital
control. Can't say that I've ever had a problem with any of these before.

Anyway, is there a more nostalgic way to listen to 60s hits than on a MW
portable with a tiny speaker?!


How about one of these for nostalgia and low-fi
https://www.flickr.com/photos/nhwilber/4701108988/
I repaired one a year or more ago, the owner is supposed to be in the UK
and collecting it later this week.
Pioneer must be embarassed , its first domestic product.
Hardboard deck and no electonics , relied on the old telephone carbon
granules principle to feed a speaker, seriously tinny and tiny


The nerve of them to put Hawaii on the box, after what they did to Pearl Harbor!

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Old June 12th 20, 01:38 AM posted to sci.electronics.repair
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Default Fan causing MW RFI

Fantasia ceiling fan (mains powered, with 6-speed
reversible dc motor) which is causing a lot of interference on MW. FM
is not affected. The interference is there on forward or reverse
rotation, worsens as the speed is increased,, and appears on portable as
well as mains-powered radios.


try a few turns on a fairite core on the power leads at the device
type 75 are only about a $1 , I put them on everything in my home
ko6kL.... more on my qrz.com page.

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