Products > Test Equipment
DP832 - Fan Replacement 2018
Gandalf_Sr:
Looks good, didn't you want to change the big resistor on the PCB?
JDubU:
--- Quote from: Gandalf_Sr on March 21, 2020, 04:23:48 pm ---Looks good, didn't you want to change the big resistor on the PCB?
--- End quote ---
I would have preferred to do that, but I didn't want to take everything apart to get good enough access to it.
Also, I wanted to be able to put the original fan back in easily if the replacement didn't work out (e.g. not enough air flow).
klausES:
If you remove the grill from the sheet metal of the back wall
(a good move and nicely protected the cut edge)
you should turn it over right away.
The sheet metal cross was the only reason that was justified to have the fan sucked out of the housing,
since the stall noise (if the suction side is close to a sheet metal cross) would have been much louder.
Since this unfavorable circumstance no longer exists, it would be more favorable in terms of flow technology to blow the heat sink.
Even if e.g. the PTC / NTC sits further forward or even in the front for measurement and thus shows a lower temperature of fresh air drawn in
(housing under negative pressure) (this would only be obviously better)
the actual effective temperature is reduced when the air is blown (upside down fan) inside and on the components.
Since the temperature difference between the outside air and the heat sink is decisive here,
the amount of heat that is dissipated when the outside air that is not preheated is blown in is really higher.
JDubU:
--- Quote from: klausES on March 21, 2020, 04:40:13 pm ---If you remove the grill from the sheet metal of the back wall
(a good move and nicely protected the cut edge)
you should turn it over right away.
The sheet metal cross was the only reason that was justified to have the fan sucked out of the housing,
since the stall noise (if the suction side is close to a sheet metal cross) would have been much louder.
Since this unfavorable circumstance no longer exists, it would be more favorable in terms of flow technology to blow the heat sink.
Even if e.g. the PTC / NTC sits further forward or even in the front for measurement and thus shows a lower temperature of fresh air drawn in
(housing under negative pressure) (this would only be obviously better)
the actual effective temperature is reduced when the air is blown (upside down fan) inside and on the components.
Since the temperature difference between the outside air and the heat sink is decisive here,
the amount of heat that is dissipated when the outside air that is not preheated is blown in is really higher.
--- End quote ---
Good points.
I'll give it a try.
timber23:
--- Quote from: JDubU on March 21, 2020, 03:43:28 pm ---I finally got tired of the unbearable fan noise on my DP832 and did the replacement. It is now really, really quiet. Just the soft sound of moving air.
--- End quote ---
Thank you for presenting your modification and the part list. After my first test I wondered that the fan did not work at all... As you mentioned red and black are swapped...
For comparison I measured the sound level before and after the modification. I can still hear the fan. It is still loud from my point of view. Maybe I have to put a resistor in series reduce the voltage and rpm a little bit? The idle temperature rises to about 27.5 °C after 10 minutes. As suggested I changed the airflow direction to blow inside the device.
Some pictures the process:
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