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Fan replacement on the Rigol DP832

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HighVoltage:
I tried a different fan in the LeCroy 354 mentioned earlier in this thread and it did not work out at all!
The scope got hot and needed the high airflow.
Well, I reinstalled the old fan and sold the scope, it was just too noisy.

So, be careful on some equipment, it needs the high airflow.
May be the Rigol DP832 is one of these, I do not know.

ElektronikLabor:

--- Quote from: HighVoltage on August 25, 2015, 01:04:18 pm ---So, be careful on some equipment, it needs the high airflow.
May be the Rigol DP832 is one of these, I do not know.
--- End quote ---
Thanks for the warning; until now, I have no problems.

SaabFAN:
I think I mentioned this before, but just to be sure :)
There are Fan-Adaptors available, which effectively increase the diameter of the fan at the expense of some added length. If you have the space on the bench, you can add a 120mm fan this way, keeping the high air flow, but also making it really silent.

julius79:
    Hello gents , I just bought the DP832 and it's extremely annoying ,the fan noise , it's as i have a mill near by , i can't work like this !
So i have google for a silent fan and found this post .
I tried to replace the fan with the  https://www.quietpc.com/nf-a8-flx but this supply it's a " smart " one. The curent it's monitored, doesn't let me to use this fan.

Tried the method described by johndoe271828 on youtube and the fan speed its decreasing , i need the air out and to benefit the fan silences.

SO again like on many other things i went in to reverse engineering this part of the supply.The original fan it's consuming around 186 mA at maximum speed and 110 mA at lower speed. Apparently  has 2 modes , low speed and fast speed , i measure the voltage at both modes on R 44 which it's used as current sense resistor  . On first i have around 0.8 V on R 44 and 1.5 V on second speed.From my analysis the power supply doesn't control the RPM of the fan , just it's  making  sure it's running , and it's checking that by reading the voltage from U 15 TLC 072C OPAMP on FAN_FAIL test.
The new fan  Noctua NF-A8 FLX it's not hungry like the original one SUNON, it's needed just 48 mA to run at full speed . I have checked the voltage that is on the R 44 and it's not good , it's triggering the power management ic to show that messages on the screen about "fan fail " .
So did some math and calculate the value of the new current sense resistor R 44 with 48 mA at 1.5 V and i got around 32 Ohms . I have replace the R 44 with the closest that i had , a 27 Ohms at 2 W .
The fan it's running now with no prompt of failing fan and it's silent .
I mentioned that this power supply has 2 modes of running the fan , the first one it's around 8 volts where my fan it's fully silent and the second mode at 12 volt in full speed it's noise it's bearable . Now it's doing the job, taking the hot air out  in silence .
Please check the hand made electronic schematic of the fan circuitry of DP 832 if you wanna get silent . Some picture are attached too.

raptor1956:
The problem I have with just about all these quieting mods is that the fans they use to replace are quieter because they've been designed to run slower and move less air.  The modified unit will be quieter but it will also tend to run hotter because the fan doesn't move as much air.

It would be nice of the component makers used larger fans than can be run slower, but they don't and they don't provide the room to install a larger fan so you're stuck switching one 80mm fan for another 80mm fan.

What might work is stacking two of the quiet fans on top of one another to increase flow rate and current draw for the fan, but, once again, they don't tend to have the room to do that.  Alternatively, picking a fan that's a bit thicker, 20mm versus 15mm for example, so that even if they run slower and therefore quieter the volume of air moved will be much closer.

Sadly there are not a great many fans of a given size that come in several different thicknesses and doubling them requires the room to do so...


Brian

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