John, KB1YD, recently came up with a brilliant method to fix the fan noise on the 7000DLE and gave me permission to post it here.
As you may know, the root cause of the problem is reported to be the PWM controller waveform. John reasoned that the old trick of using a snubber circuit to soften the edge rates on the PWM waveform might help. According to John, this makes his fan "as quiet as a mouse".
John very graciously provided this schematic:
![Image](https://farm5.staticflickr.com/4687/25482489608_ed9529e5c8_c.jpg)
Conveniently, the fan control circuit on the 7000DLE is arranged such that you can actually install this circuit without opening the case, as the external fan connector is wired in parallel with the internal fan:
![Image](https://farm5.staticflickr.com/4641/38643622484_332925ac67_c.jpg)
If you try this and find that it works for you, please post here and let us all know.
Disclaimers: I don't have a 7000 and have not tried this for myself. There are no oscilloscope measurements of the resulting waveform nor any fan speed measurements either (yet). Do this at your own risk.
73,
Scott