[time-nuts] Replacement fan in SR620

[Magnus Danielson]

Charles,

On 02/02/14 21:58, Charles Steinmetz wrote:
> Magnus wrote:
>
>> Also, the fan-noise did not change a lot by drying to damp the top
>> lid, so it seems the fan emits it mostly as a direct mode.
>>
>> The older unit has a high hiss to its fan
>
> That is what I have observed, as well.  The noise is mostly fan blade
> noise and some bearing noise coming directly out the back of the unit.
> I did not find that the inlet vents were a significant source of noise,
> or that increasing the inlet area caused the fan itself to run quieter.
>
> You probably wouldn't notice a substantial noise reduction until you got
> down to a fan with a 15-18 dBA noise rating, and that would move so
> little air that you'd probably fry the counter.  The Papst fan has about
> the same noise rating as the original Delta, so I wouldn't expect
> changing the fan to have a big effect on the amount of noise (but, as
> you say, the noise spectrum may be different).

Well, with a ball-bearing noise it's much worse than fan-blade hiss.

Fan-blade hiss is result of running at stupid speeds without achieving much.

Anyway, I will probably get a new fan so I might as well get two.

Finding out why the UPS won't start and parts of my rig with it is 
however higher up on the to-do list now that I figured that much out... 
and more clean-up.

Cheers,
Magnus