Loud Fan NV4108-HS

Have some questions or having issues with your DVR/NVR(s), Post them here for the mods and other users to assist you with.
plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

The Noctua fan has arrived, and it's built in such a way that the grille is on the outside (exhaust) part of the fan, so cutting away the mesh grille on the NVR is no problem since the fan itself comes with a built-in grille. I was going to report on installing it but there's no obvious way to shut down the NVR, see this post, as soon as I can find out how you're supposed to shut it down I'll install the Noctua and report back.
james_s
Posts: 17
Joined: Fri Dec 29, 2017 2:54 am

Re: Loud Fan NV4108-HS

Post by james_s »

I unplugged the fan in mine too, it has been running for several months without issues and temperature measurements show things stay within a reasonable range. The fan may be necessary if you have a particularly hot-running hard drive or live in a hot climate but in most cases you should be ok to unplug it.

Just to clarify, this worked for me but do so at your own risk, I will not take responsibility if you manage to cook your device.
plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

So I finally managed to shut down the NVR, see the details of this saga here. Fitting the Noctua fan was a bit tricky because neither the electrical nor the physical connectors are compatible with the NVR. The electrical connector is 3-pin while the NVR is 2-pin, to get around this I cut off the keying lug on the NVR and plugged in the two power pins on the 3-pin fan connector, leaving the sense pin unconnected:
nvr_fan_cable.jpg
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The outermost pin on the NVR PCB is +12V, the inner one is GND.

Then I had to attach the fan to the case. The Noctua silicone vibration-damping mounts don't really work in this situation, and the existing fan uses self-tapping screws that are too small for the Noctua fan. Conversely, the Noctua self-tapping screws won't fit through the smaller mounting holes. I thought of reaming them out to fit the Noctua screws, but I'm not really a fan of self-tapping screws anyway since they're typically single-use only, once they've cut their threads you can't remove and reinsert them without losing a lot of grip each time. Also, by solidly anchoring the fan case to the NVR case you're defeating the vibration-damping grommets in the fan case.

Instead, I used some M5 bolts, which clamp onto the silicone grommets rather than biting into the fan case:
nvr_fan_1.jpg
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Another view:
nvr_fan_2.jpg
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(Continued in the next post, looks like I've run out of credits).
plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

(Continued from the previous post)

Finally, I closed the case up again. The heads of the mounting bolts stick out a bit so there's a very slight bulge in the side of the case, but it's barely noticeable because there's a gap between the inner and outer shells anyway:
nvr_fan_external.jpg
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Connected everything up again and it works fine, the fan is only just audible in a dead quiet room. I used the low-noise cable that came with the Noctua, this has a built-in 10k resistor which lowers the voltage and thus the fan speed, but even with that inline it still moved a lot more air than the stock fan did. If I'd known it was that efficient I'd have used the ultra-low-noise cable, which would presumably give about the same performance as the stock fan but with close to dead silence. I'm tempted to swap it in, but can't stand the thought of having to go through the pain of shutting the NVR down again.

Amcrest, you owe me an NVR with a working on/off switch.
plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

As an update, today I went through the full three-part theatrical performance with backing actors and orchestration that's required to shut the NVR down and swapped the low-noise for ultra-low-noise cable, which just adds a higher-value dropping resistor to run the fan at an even lower speed. The result still, subjectively, moves a bit more air than the stock fan did but is now virtually silent, in a dead quiet room you need to get within about 1m of the NVR to hear it running.

So in summary, cutting away the grille and fitting a Noctua NF-A4x20 FLX cabled for ultra-quiet operation makes the NVR dead silent, with no impact on cooling.
plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

plusfour wrote:So the fan in mine is a Sunon HA40101V4,
An extra comment on this, now that I've removed it I can see the markings on it and the airflow indicator shows that it was installed in a somewhat unusual configuration, sucking air into the case rather than pushing it out. This also explains why the plastic shield that's part of the fan casing was facing into the inside of the NVR case, not on the outside where it'd protect the fan blades.

Given that the HDD right in front of the fan is likely the hottest component, you'd want the fan sucking air out over the surface of the HDD rather than blowing cool air onto the HDD, where it gets heated up and then hits other parts of the system. In other words the progression should be:

| Cooler-running electronics --> | Hot HDD --> | Fan --> |

not:

| <-- Cooler-running electronics | <-- Hot HDD | <-- Fan |

So it looks like the stock fan is mounted backwards. Another reason to put in the Noctua, with the airflow swapped so the hot air off the HDD is the final stage before it's exhausted from the system.
Yardstick
Posts: 11
Joined: Wed Dec 26, 2018 2:29 pm

Re: Loud Fan NV4108-HS

Post by Yardstick »

I purchased an Amcrest system that included this NV4018-HS NVR a few weeks ago and have talked to Amcrest's tech support about the fan noise several times since. Yesterday I found this thread and confirmed my findings that this fan and the existing case ventilation restriction is a poor combination. This is apparently not a new problem for Amcrest systems in general. There are several threads on noisy Amcrest fans and even an instructable about quieting an Amcrest DVR by replacing the fan. Maybe the Amcrest engineers need to review an article on the "Effects of Grille Patterns on Fan Performance/Noise". My fan is also in a configuration to suck air into the case. It is so restricted that I can't tell that there is any air movement going on in there.

I did a little investigating with my thermal camera to attempt to identify the component(s) requiring the fan at all. Amcrest claimed that the HDD required cooling. The top cover on my HDD is reflective, so the emissivity gives a false reading in the image, but you can see the edges are not that hot. It turns out that their board is pretty toasty!
flir_20181226T095018.jpg
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The component with the heatsink must be pumping out some heat, but the heatsink is doing its job. The next real hotspot is a transistor (that I didn't go to much trouble trying to identify).
flir_20181226T095637.jpg
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plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

Thanks for the Effects of Grille Patterns on Fan Performance/Noise link, very interesting! In my case I just used the plastic struts of the Noctua fan body as grille, so no explicit grille but the fan body itself protects fingers, unless you're really determined.

The thermal image is also interesting, another possibility with the single heat source on the motherboard is to mount an alu block that reaches up to touch the case, so the case is acting as a heatsink. Since I haven't had any problems with it so far, and the air being exhausted is barely warm, I'll leave mine alone for now...
plusfour
Posts: 80
Joined: Tue Mar 06, 2018 4:04 am

Re: Loud Fan NV4108-HS

Post by plusfour »

Yardstick wrote:The next real hotspot is a transistor (that I didn't go to much trouble trying to identify).
Do you have a closeup shot of the motherboard? Just wondering what that hot component could be, could it be a three-terminal regulator, or if it's a PoE version a transistor acting as an external pass element for a switchmode regulator used to drop the 48V down to whatever the MB needs? If it's the latter than there should be a switchmode controller paired with the transistor, e.g an 8-pin IC like the widely-used MC34063. Even then you wouldn't expect the transistor to get that hot, so a photo of the device and surrounding circuitry would be useful.
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