I have finally found time to replace the fan of my DP832.... the volume of the fan noise was always annoying me.
Though a surprise was waiting:
I wanted to replace it with the above mentioned Noctua, thus I purchased one for about 10 Euros.
But during the conversion I noticed that it was not necessary at all, these 10 Euros can be saved.
1) The Noctua allegedly has the same air performance as the original Sunon fan, but subjectively it produces much less air. It rotates with 1600 rpm where the original Sunon runs with 3200 rpm.
2) The fan cover on the back of the DP832 covers approx. 50% of the surface, i.e. the fan has to produce an unnecessary amount of power to squeeze the air out of the small openings.
Here I thought, to compensate the lower air pressure of the Noctua I would just remove the fan cover of the back of the DP832.
Therefore I separated the fan cover with a Dremel and replaced it with a thin grille cover. The reason was so that the Noctua fan could produce about the same air performance (without the fan cover) as the Sunon (with the fan cover) due to the lower air resistance.
First try: original Sunon fan without the fan cover ..... and ..... whow! The whole unit is 10dB quieter, so it's only half as loud as before! Just by removing and replacing the fan cover. Probably due to the eliminated turbulence at the sharp corners of the cover and of course of the removed extra resistance.
2nd step: Since the air resistance now has become much smaller by removing the cover, the original fan can now turn slower for the same amount of air. A 47 Ohm resistor in series makes the DP832 very very quiet with approximately the same amount of air running through the electronics. In fact, it is that quiet now, that the DP832s chirping display illumination is disturbing.
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
Well, since I had the 90mm Noctua fan already purchased, I now installed it together with the 3D printed adapter from Thingiverse I already printed. Result: the DP832 is now almost inaudible (but the display).
Note: since this fan needs less power and the DP832 gives an error message, I had to connect 220 Ohm in parallel to the fan.
So, long story short: save your money, you don't need a new fan. It is sufficient to remove (Dremel) the fan cover to lower the volume already by 50%. If you want to make it even quieter, solder a 47 Ohm resistor in series with the fan (you might need to connect the mentioned 220 Ohm resistor in parallel to the fan connector).
Edit:
Temperature:(see post above how to switch on the temperature display).
- Idle (no load): 30.5°C after some time
- 90W load (* see below): 76°C after 2 hours
after switchoff the load (=idle) and 5 min. waiting time: back to 55°C
*= I set channel 1 and channel 2 to 15V and 3.2A; I then connected them serially (30V, 3.2A max) and used an electronic load to draw 3A. I let it run for >2 hours.