Warning: Fanspeed too slow - need advice (NAS520)

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Josathome
Josathome Posts: 14  Freshman Member
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Since 2 days my NAS 520 (watch dog) sends me an email message that fan speed is too slow. The NAS is making a beeping sound. Looking at the timestamp, this happens in the morning when starting up again (I have a schedule for that). When checking NAS health, I can see a fan RPM of ca. 400 RPM. After manual re-start I get ca. 460 RPM (and no error messages). So something is slowing down the fan speed in the morning start. Since 2 days it also below 0 deg C outside here so I can imagine that during the night (when the NAS is switched OFF) the NAS gets relatively cold (room heating is also OFF) and at startup in the morning (cold, room heating is still OFF) the fans lubrication is somewhat less. Or the fans are dirty and I have to clean them (the axle)...
Ideas what could be the root cause? And how to solve? PS What s normal fan speed?

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  • Josathome
    Josathome Posts: 14  Freshman Member
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    Hi Tobias, I found an alternative fan, based on data from the back of the fan itself. I go for that option. It is only € 5,00

    Thx for support
  • Josathome
    Josathome Posts: 14  Freshman Member
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    Hi There, just a last one to this topic. The original fan from YS TECH was not anymore available and I bought an alternative type from Arctic as replacement. So far running without issues at 857 RPM. It is a 4 pins fan, so RPM should be variable (I am not sure if my NAS is regulating the RPM actively or not; original fan is 4 pins too).

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  • Zyxel_Tobias
    Zyxel_Tobias Posts: 200  Zyxel Employee
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    Hi @Josathome

    It may be a dirty FAN or to cold, could happen yes.

    Can you may open housing and clean it up a bit?

    It should run faster, may around 1200 RPM.

    Let me know if it helps, if not we can may help using RMA to replace FAN.

    Kind Regards,

    Tobias
  • Josathome
    Josathome Posts: 14  Freshman Member
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    OK, are there special instructions how to open the main housing?
  • Josathome
    Josathome Posts: 14  Freshman Member
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    Hi there, I opened the housing and cleaned the fan as well as everything I could reach easily. Re-assembled everything but fan speed stays just above 400 RPM. So it is not the cold (maybe the cold contributed a little bit), as the NAS was for some time in my warm living room). I will replace the fan as this seems an easy task. However, there were no details on the fan with details what to buy.
    Need advise about fan specs and connector. Does anyone know?
  • Zyxel_Tobias
    Zyxel_Tobias Posts: 200  Zyxel Employee
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    Hi @Josathome

    You can request a new FAN from our RMA department:

    https://support.zyxel.eu/hc/en-us/requests/new?ticket_form_id=360000009533

    Kind Regards,

    Tobias
  • Josathome
    Josathome Posts: 14  Freshman Member
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    Answer ✓
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    Hi Tobias, I found an alternative fan, based on data from the back of the fan itself. I go for that option. It is only € 5,00

    Thx for support
  • Josathome
    Josathome Posts: 14  Freshman Member
    First Anniversary First Comment
    Answer ✓
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    Hi There, just a last one to this topic. The original fan from YS TECH was not anymore available and I bought an alternative type from Arctic as replacement. So far running without issues at 857 RPM. It is a 4 pins fan, so RPM should be variable (I am not sure if my NAS is regulating the RPM actively or not; original fan is 4 pins too).

  • Mijzelf
    Mijzelf Posts: 2,639  Guru Member
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    Josathome said:
     (I am not sure if my NAS is regulating the RPM actively or not; original fan is 4 pins too).

    It is.

  • Josathome
    Josathome Posts: 14  Freshman Member
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    Hi Mijzelf, Thx for this reply. I today checked RPM again and see the RPM is now really lower in the 600 range. The CPU temperature is also lower w 28 deg C, so a lower fan speed makes sense and seems to be working.
    Additional observation: I was running a power ON/OFF schedule w the "original fan" installed. Powering up in the morning (after a cold night) giving an RPM just above 400. I saw that the watchdog alerts were always sent on exact the same time (exact to the second) i.e. 2:50 mm:ss after power ON. Unfortunately I didn't record the CPU temperature at that time, but at start up it will be for sure close to 10-15 deg C. And as a consequence the NAS RPM controller may be doing its job reducing fan RPM to a value that triggers an alert???
    As a test I will switch the power schedule back to ON again and see what happens in the morning. And record the temperature..

  • Mijzelf
    Mijzelf Posts: 2,639  Guru Member
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    A warning that the fan speed is too low is not a warning that the system is too hot. I think you get that warning when the fan speed is lower than the controller expects. As far as I remember the fan is blowing full when you power up the box, and lowers when the OS is booted. So the fan controlling daemon might warn you when the rpm is lower than, say, 3000 when the daemon is started.

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