The cooling fan on my DVR is getting very noisy. It is a 50mm 12v DC 0.7W
fan and the closest match I can find locally is a 1.2W fan at Maplin (code
RY86T). Is the extra power needed likely to be a problem?
I assume (but may be wrong) that the 0.7W fan is fitted due to cost cutting
and bulk buying in the manufacturing process and not due to the PSU limits.
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Not all fans are equal and some are very noisy so it's not just power
that you need to consider. For a computer noise may not be an issue but
may people complain about the noise made by a fan in a PVR/DVR that sits
in a box under the TV. The noise figure is often directly related to
the airflow figure and a lower airflow means lower power.
30dBA noise, Power 1.2W
22dBA noise, Power 1.08W but with a lower airflow than the Maplin fan.
You may also need a series resistor to make the fan run slower/quieter.
Try also removing the existing fan and then the sticky label or plastic
cover over the bearing and put one drop thick engine oil (NOT WD40) in
the bearing. Cleaning all the dust off of the fan may also make it less
The lower power one may have been chosen for quietness as well.
Small fans can be extremely noisy and at a frequency range that will be
An example of this is the small fans (40mm IIRC) that are used in 1U
(44mm high) rack mounted servers beloved of hosting providers.
Cooling on these can only be achieved front to back unless they are
spaced with a gap in between and that's undesirable for space reasons.
Additionally, there is a row of disk drives across the front and
therefore a fair amount of heat. Usually in the middle there is a
row of these small fans, sometimes even two deep. In some cases, one
could imagine that Pratt and Whitney were the manufacturers.
For a DVR, one needs virtual silence , so small low powered fans are
the order of the day.
It's also possible that there is some electronic speed control based
on temperature. Another trick is to apply the rated voltage at startup
to get the fan turning and then to drop it back to lower voltage for
quieter running. The control electronics may only be able to support
a lower powered fan.
If you can't identify the precise spare, then take a look at the label
on the fan itself and identify the manufacturer or the part number.
Sometimes the same part number is used by several manufacturers (one
chinese manufacturer makes and the others private label it). At any
rate, a Google search on the part number or manufacturer will usually
find a web site, hopefully in Engrish, and from there you can get the
spec. From there you can look for an alternate or possibly a supplier
Try if you can to get a fan with ball bearings or ceramic bearings
rather than sleeve bearings as these seem to last longer.
Having said that, 50mm is not one of the most popular sizes so there
may not be a huge amount of choice.
As I cannot get a new fan today I'll give the oil suggestion a go this
afternnoon after the hospital visit to see my Mum. I have 40 litres of
15W40 diesel engine oil in my shed. It is my assumption that the bearings
are failing on the old fan but I do note your point about the different
noise outputs on new fans.
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WD40 is actually good for cleaning out the old oil and muck.
A drop applied, and then absorbed back into kleenex will draw
out the old oil/muck. Repeat a few times. Then allow to dry,
and then re-oil. (Don't run it for any length of time without
re-oiling -- although it might appear that WD40 alone fixes
the problem, it's not a lubricant and you would be running the
bearing without any lubrication.)
Sometimes the dust build-up is actually responsible for what
might sound like a bearing noise.
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Yes - my Acorn RPC has one of those on the PC card which is a 586 type. I
didn't realise just how noisy it was until removing the card which I
don't use anymore. Acorns produce so little heat you just about get away
with only the PS cooling fan which is a great deal quieter despite being
Now imagine 6 or more of them per server, about 40 servers per 19" rack,
they generally come on at full tilt and all being well are able to idle
down after a minute or so, once they realise the A/C is doing OK.
Cheers for that. The fan is easily identifiable (Sunon KD1205PFS3)
The first google hit shows
which is indeed a sleeve fan and I am sure the bearings are on the way out.
I was hoping to puchase an equivalent fan locally than mess about with mail
order. I will give the RS website a look later as I will be in Leeds next
week and will pass their store on my travels.
Larger fans generally can run more quietly for a given amount of
airflow because of the lower rotation speed if under run.
Doesn't studio/control room equipment tend to use this trick (at least
where it is located in noise sensitive places?)
Sadly RS's site is down for maintenance until Wednesday. However I
did look in their paper catalogue for you and there isn't a lot in
50mm. They seem to sell Papst in preference, but there was only a
sleeve bearing 50mm 1W fan.
The Sunon fan is rated at 35dB A, I notice. This seems a lot in
comparison to most which are at around 25-27 so I suspect the
measurement method is different.
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You'd hope so, wouldn't you? But you wouldn't believe the racket the
cooling fans make on lots of lighting gear where the PS are just plonked
down on the studio floor. Perhaps it's made with pop concerts in mind.