Warning, these mods will void your warranty!!

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I’ve had one of these for a while now, the DP832 version, comes software crippled with mono screen (even though the screen is colour) and Upgrade to the model to improve resolution and add advanced monitoring, triggering, and programming capabilities.

The only issue I have had with this unit is the noise, OMG it’s loud. Even on the low fan speed (i.e. no load) it’s loud. see blow it’s 52dB at idle and 62dB at full fan speed.

It was time to do something about this, I could not hear myself think anymore. Remember these are mostly used in Lab where you have other noise sources like other instruments, Aircon etc… it would not be noticed in such an environment. However in a dead quiet home/workshop it’s loud.

So I took it apart to see what was inside. After using a Torx screw driver to remove the side Handle, then the 4 rear rubber boots I could slide off the case towards the rear, then I had to take off the 6 small Torx to slide the lid towards the front of the unit and then lift from the back to detach just one small ribbon cable and I was the able to swing the lid towards the front. There lies an 80mm 12v 2 wire fan.

The Fan is attached to the lower main board with a JST HX 2.54mm 2 pin female plug. As below:

Model No.	Bearing	Voltage	Current	Power	Speed	Air Flow	Pressure	Noise	Weight
		(V)	(A)	(W)	(rpm)	(CFM)	(inchAq)	dB(A)	(g)
MGA8012HR-O25	R	12	0.29	2.88	3000	37.20	0.123	34.6	90

So next step was to work out why the fan was so loud. looking at the specs its a 3,000 RPM fan @12v, I measured the voltage at low speed and full load, it was 8v/12 respectively. So it’s just controlled with voltage as it’s only a 2 Pin Fan, no Tach or PWM pins here.

First thing I noticed is that when the Fan was running out of the case it was no where near as load as when in the chassis. Ah ha, taking a look at the rear chassis grill it looks very congested, as it’s a) not fully open and b) Laser cut with sharp edges.

When looking for a replacement 80mm Fan, most high quality low noise fans had a lower CFM and lower Max RPM rating. So I decided to remove the standard rear grill as it would allow the lower flow fans for work more efficiently and also it would seem greatly reduce the noise.

The Fan I finally settled on was the 80mmx80mm-x25mm Noctua NF-A8 FLX 3 pin FAN. Max RPM 2000 and around 30 CFM.

https://noctua.at/en/products/fan/nf-a8-flx

Step one was to get rid of the standard restrictive rear fan grill, the best way to do was was to just cleanly cut it out without grinding anything as I didn’t want shavings flying into the main board and didn’t want to totally dismantle everything. So I decided to use string wire cutters to remove it safley.

I ended up using this fan guard below for leat resistance should be a perfect fit.

https://www.altronics.com.au/p/f1022-sunon-80mm-metal-fan-guard/

Fitted the new Fan and grill looks great. Still intending on keeping the same air flow direction, (inside -> out).

Next steps was to make up a cable to attach the JST connector to Fan with the correct polarity. The old fan was using ~140mA-170mA, the new fan was using around ~70mA. The issue with this is that the PSU would now sometimes complain that the Fan is not connected and would essentially stop working. So the way around this was to put a 5w 150 Ohm Resistor in parallel to increase the current usage to around 140mA. yes it’s only dissipating around 1w so by using a 5w resistor it will stay nice and cool. I soldered it up and heat shrink wrapped the new cable.

ok now time for the new sound level measurements, I can tell you it’s made a huge difference and the flow with the new Fan is pretty much the same as the old nosy Fan.

Much much better than before, now I can concentrate on what I’m doing. 🙂

	Fan noise No Load	Fan noise Full Load
Before	52dB	62db
After	38dB	48dB