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New 24v power supply question

Discussion in 'General Talk' started by lofton, Feb 4, 2016.

  1. lofton

    lofton Well-Known
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    the other day I received the shiny new MW PSU that Open Builds sent to replace one I bought recently. I printed up a terminal cover with power switch and with voltmeter in hand, powered up the PSU. The fan didn't come on. I said a dirty word (I had already shipped the old unit back and don't own a fleet of PSUs) and wanted to resume setup on my Delta. In case the power switch had gone bad I removed it and hooked the power cord directly to the PSU. Left the terminal cover off. Plugged it in and voila, the green led lit up. Voltmeter informed me that 24.0 volts were streaming out. Still, no fan action. On the old unit the fan started (with gusto...read: noise) whenever the unit was powered up.

    So, is the new PSU faulty, or does the fan only start when the unit gets warm? Thanks for any advice (or ridicule) you care to offer.
     
  2. Mark Carew

    Mark Carew OpenBuilds Team
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    Not faulty, you are correct the fan is controlled by the control board.
     
  3. Steve Fox

    Steve Fox Veteran
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    I don't think it comes on until some threshold of heat is crossed, like you thought.
    My machine only uses about 12 amps on a 30 amp power supply and I've never had the fan come on.
    The case has never gotten warm to the touch either.
     
  4. apburner

    apburner Journeyman
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    So if I wish to keep the old PS can I just send money. I would like to use it on my 3d printer when I get to finishing that
     
  5. Ronald van Arkel

    Staff Member Resident Builder Builder

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    The new PSUs are high efficient, 88%, they are completely different than the "old" 65% efficiency PSU. Higher efficiency is less heat, so, besides some leak current, 12% is converted to head while the other one converted 35% to head and you need to have a constant fan speed for that. The new PSUs need to get to 40ºC to have that fan turn on ;).

    Now, the new PSU is 350W, but real watts and not Chinese Watts. If that PSU would be Chinese Watts it would be labeled 535W :D. The new PSUs can provide constant 350W until it gets to 50ºC, 280W @ 60ºC, 210W @ 70ºC. The current NEMA 23 motors we have will pull about 28.8W (1.2A@24v DC) per coil, so even if you have 4 motors and use both coils at the same time (you never will!) you will need to provide 9.6A, thus 230.4W... on paper. The 500W Chinese PSU won’t crap out that fast either but for sure it was 500W peak, and about 300W continuously @50ºC.

    As a plus, the new PSUs have a MTBF of 327.900 hours! [​IMG]

    Anyway, would be nice to see more feedback on the new PSUs [​IMG]. And if you want to ask in-depth technical info, just ask.

    -Ronald
     
    GrayUK and Mark Carew like this.
  6. lofton

    lofton Well-Known
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    Thanks for the data, Ronald. By my calculations, at 327,900 MTBF divided by 8,760 hours in a year, that little sucker will still be operating for more than 37 years. That's way longer than my personal "MTBE." E = Expiration.

    One more item to go into my will.
     
  7. Ronald van Arkel

    Staff Member Resident Builder Builder

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    :D

    Well, the fan is sleeve bearing and I don't think it will "live" longer than 50.000 hours, so 5.7 years, about that.

    -Ronald
     
  8. apburner

    apburner Journeyman
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    Well my old PS will be on it's was tomorrow. Sorry for the delay but I work 12 hour shifts and find it hard to get anything done when I am working.
     
  9. Kyo

    Kyo Master
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    Just got the new PS in the mail yesterday. Did I miss a recall on the old units? What initiated the switch? It will be a few day before I am able to send the old unit back ( have to drive to the postal office in town )

    I really like how low profile the mean well unit is. I am already looking to upgrade my printers electronics to 24v stuff as it is thin enough to mount under the bed unlike the other units I have on hand. This new unit should match my c-beam machine well.

    Thanks for the upgrade! I will have more feed back once I get it mounted and in service.
     

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