[time-nuts] Replacement fan in SR620

[Magnus Danielson]

On 02/02/14 20:13, Volker Esper wrote:
> Magnus,
>
>> Yes, and the EBM-Papst 624 matches it well. The Papst seems to have
>> much lower noise from the datasheet.
>
> There's yet another problem: the mechanical construction conducts the
> fan noise to the case, so the noise is kind of amplified by the case. I
> felt somewhat disappointed after replacing the fan, don't expect too much.

You mean the fact that the lid acts like a speaker membrane? So true.
The best cases I have seen have suspended mounting for fans and other 
vibration-makers (hard-disks).

> I just read the postings of Charles and I, too, was unhappy with the
> startup behaviour. I changed the values of the driver circuit, but kept
> the sensor in the tunnel. That helped making the motor speed rising
> monotonically.
>
> The air inlets are too small - that's true, if you need so much air
> flow. We agree that the fan speed is at it's maximum, not at it's
> equilibrium. So I tried to separate the heat sources. At the right (and
> left) side of the case various voltage regulators heat the side wall. I
> placed a heat sink with vertikal fins from the outside on that wall, the
> screws of the regulators screwed into the aluminium. I'll  further place
> a wall inside the counter right before those heating parts. The
> experiment isn't completed yet, but I'm keen enough to claim that it'll
> help to stabilize internal temperature particularly at the sensitive
> components.

It's indeed clear that the voltage regulators contribute a lot of heat.
That's why I proposed to put a fan on the outside.

As built, it is easy to "cook it" when it is put too crowded.

Cheers,
Magnus