Can Transformer Hum Sound like a Crackling?

My Sanyo Combination Microwave EMC 8787B purchased from Target
frequently makes a low crackling just audible noise when it is
not in use but plugged in. The noise appears to be coming from
the front bottom right hand corner and sounds like something
arcing. The noise stops if the power is turned off at the wall.
The oven otherwise appears to work perfectly.

When I asked Sanyo via their customer support on their website
they said it was transformer hum, normal and safe. The sound is
coming from where they say the transformer is located but I
would expect transformer hum to be rhythmic with a fairly
constant frequency and volume - the crackling I hear randomly
changes in volume and frequency. What do you think. It's only
a few months old and still under warranty so I don't feel
disposed to opening up for further investigation.
--
Regards
Blue

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On 12/12/2011 9:42 PM, aussiblu wrote:
> My Sanyo Combination Microwave EMC 8787B purchased from Target
> frequently makes a low crackling just audible noise when it is
> not in use but plugged in. The noise appears to be coming from
> the front bottom right hand corner and sounds like something
> arcing. The noise stops if the power is turned off at the wall.
> The oven otherwise appears to work perfectly.
>
> When I asked Sanyo via their customer support on their website
> they said it was transformer hum, normal and safe. The sound is
> coming from where they say the transformer is located but I
> would expect transformer hum to be rhythmic with a fairly
> constant frequency and volume - the crackling I hear randomly
> changes in volume and frequency. What do you think. It's only
> a few months old and still under warranty so I don't feel
> disposed to opening up for further investigation.

You could try it on a different power circuit away from its current
location to see if it is an issue with power line noise.

Noises when not turned on would be enough inducement for me to take it
back regardless of what the Sanyo representative thinks it is.
Transformer hum is exactly that... a hum at 50 or 60 Hertz depending on
where you are. Crackling does not constitute a hum.

Take it back and say you think it is unsafe and are afraid it might
catch fire. Let them prove to you that it's safe. Don't just take their
word for it over the phone.

--

Krypsis

"aussiblu"

> My Sanyo Combination Microwave EMC 8787B purchased from Target
> frequently makes a low crackling just audible noise when it is
> not in use but plugged in. The noise appears to be coming from
> the front bottom right hand corner and sounds like something
> arcing. The noise stops if the power is turned off at the wall.
> The oven otherwise appears to work perfectly.
>
> When I asked Sanyo via their customer support on their website
> they said it was transformer hum, normal and safe. The sound is
> coming from where they say the transformer is located but I
> would expect transformer hum to be rhythmic with a fairly
> constant frequency and volume - the crackling I hear randomly
> changes in volume and frequency. What do you think. It's only
> a few months old and still under warranty so I don't feel
> disposed to opening up for further investigation.
>

** See if the noise changes if the oven is bumped or tapped firmly with the
handle of a screwdriver in that area.

If it does react, then there is a bad connection or solder joint.

BTW the transformer in question is a tiny PCB one - right ?



.... Phil

Thanks All


I'm in Bibra Lake Western Australia. Looking through the grill
for the oven light I can see a box shaped object about 40mm X
40m X 90mm which I assume is the transformer (there is also
evidence of matching mounting bolts on the bottom of the oven in
this area) . Unfortunately (or I guess for safety sakes,
fortunately) it and everything else there appears covered by
foil so without opening it up I can't confirm it's the
transformer or ID the type. Opening it will doubtless void my
warranty.

After comparing notes with the rest of the family, who more
frequently use this combination oven, I can add the following
observations:

a) It started crackling a few weeks ago with the onset of
hotter summer weather;
b) When it happens there is also a lot of condensation present
inside the oven (cooking area);
c) It stopped yesterday with a thunderstorm bringing cooler
temperatures - the condensation in the oven also disappeared at
the same time.

I can't help wondering if condensation is getting inside the
area where the transformer is and causing it or the mains
connections to short and arc. I assume this area should be
sealed off from the cooking compartment. I suspect this seal
has failed and moisture from cooking is getting into this area
or alternatively from outside the oven. Note my house is air
conditioned with ducted evaporative air conditioning - perhaps
that contributes to the formation of condensation. The oven is a
combination microwave, convection & grill.

..

--
Regards
Blue

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I'm sure Target will give me my money back no questions asked
but I would prefer and exchange. However, I haven't found a
Target here in WA with them still in stock yet so given I
actually otherwise like this Combination Oven, and it was a
bargain price in comparison to others, I may have to accept
returning it to Sanyo for a warranty repair. I've emailed Sanyo
again.

--
Regards
Blue

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It's a backlit LCD display.

Looking in through all the vent holes have discovered here and
there it looks like all that foil is everywhere and glued in
place which might present warranty problems if I open it up
(torn foil or one time adhesive strips). But having now found
all the various places I can look in when it starts crackling
again I will darken the room and peer in looking for evidence of
arcing

--
Regards
Blue

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The backlight only goes on if you press a button on its front
panel or you are cooking with it. Banging, knocking or moving
the oven made no difference.

The heat and humidity has returned post thunderstorms and the
condensation is starting to form inside the oven again; we'll se
if the arcing sound comes back.

Sanyo tried to ring me again today but we played unsuccessful
telephone tag.

--
Regards
Blue

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