Micro ATX PSU- What manufacturer?

Discussion in 'PC Hardware' started by Paul, Dec 14, 2014.

  1. Paul

    Paul Guest

    Post a picture of the label on tinypic.com . There is a limit
    to the size of the picture, and if you upload a high resolution
    image, the site is likely to downsample it (to say 1024x768).
    I like to control the downsampling myself, so I get a legible
    image on one try. This wasn't a problem with Imageshack in the past,
    but they're entirely out of the PC space now. They also zorched
    all the old pictures (gee, thanks).

    There are volumetric limits to power conversion. It takes
    "X" cubic inches of space to regulate 625 watts. It takes
    a smaller space to do 450W. At some point, you run out of
    room with respect to dimensions, to build truly monstrous
    supplies.

    On some of the 1200W class ATX ones, you can see the chassis of
    the supply is longer than normal. Two dimensions are fixed,
    and manufacturers just play with the other as they see fit.
    Worst case, if the computer case is small enough, the supply
    and cable harness, could bump into the back of the DVD drive.

    The microATX doesn't have nearly the freedom to fool around.

    On ATX supplies, the label includes volts and amps. There should
    be some level of detail on there, as to what the thing
    actually is.

    I tried a search here, and got purely random results. So
    the search engine isn't helping, even when primed with
    "power supply" as a search term. I might as well have
    been shopping for Golf Shoes, as far as the search engine
    was concerned. It couldn't even limit the search to things
    with "power supply" in the name.

    Paul
     
    Paul, Dec 14, 2014
    #1
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  2. Paul

    Al Drake Guest

    I'm looking for a replacement for a Micro- ATX PSU mounted in a
    Surveillance DVR and would like some recommendations on who makes a good
    one. The one I'm trying to replace is obviously a cheap one as it
    crapped out after a short time. Made in China with RSY 625M V1.3 on
    label but I come up empty in my searches. I've tried Amazon but only see
    those that are 450W max. I'm assuming the 625M means wattage but I might
    be wrong. I have 6 HDDs installed so I want to make sure I have one
    that's got the power I need.

    I don't suppose anyone here has experience with DVRs and can help. I
    have posted to CCTVforum seveal times but I can't get any help with what
    I need to know.

    Thanks for any tips.

    Al
     
    Al Drake, Dec 14, 2014
    #2
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  3. Paul

    Al Drake Guest

    Ok, Paul and thanks. I'll find a camera that I can use and maybe take a
    shot of inside the case as well.

    Be back as soon as I can.

    Al.
     
    Al Drake, Dec 14, 2014
    #3
  4. Paul

    Al Drake Guest

    Ok, That didn't take that long. I found a magnifying glass and was
    able to see that is says 250W after something in Chinese and more
    Chinese and 125W so I guess I don't need something that big after all.
    I am wondering, however, about my use of my PSU tester. The display
    shows flashing LL where it checks the +12v. When I connect a 12 volt
    molex nothing changes. The DVD drive opens and closes so I know that is
    getting power. The cable to the motherboard is a 20 pinout where the
    PSUs I saw were 24. I am supposing I can still use it but will only be
    using one part of the connector? I hope I'm not over looking something
    in hooking up the tester. I get the display but it doesn't go farther
    than the "waiting" screen.
     
    Al Drake, Dec 14, 2014
    #4
  5. Paul

    Paul Guest

    Using a 24 pin ATX power, on a 20 pin motherboard, is OK.
    The extra four pins are redundant. For example, the 20 pin has
    one 12V wire, rated at 6A. When a 24 pin connector is used, one
    of the extra pins is yellow and is 12V as well. Which gives you
    closer to 12A of capacity for current flow. Since the motherboard
    only has the 20 pins, that means it's happy without that.

    Some supplies, the connector is a 20+4 style. There is a
    hinge, and the two pieces come apart. That allows plugging in
    the 20 pin section, and leaving the other bit dangling. The dangling
    bit doesn't hurt anything.

    You can also plug the 24 pin (solid connector type) to the 20 pin,
    but that's only possible if no components are to the side of the
    connector area. Sometimes an electrolytic cap is in an inconvenient
    location, and prevents direct plugin like that. Example here,
    showing the pins hanging over. Pin 1 aligns with Pin 1. Latches
    on the same side. Leaving four pins hanging over on the far end.

    http://www.playtool.com/pages/psuconnectors/24in20.jpg

    More info on this site.

    http://www.playtool.com/pages/psuconnectors/connectors.html

    *******

    With regard to your PSU tester, it sounds like you're doing the right
    things. Some PSU testers only load one rail (like maybe 5V), leaving
    the other rails unloaded. Connecting the DVD drive, only loads the
    12V if media is spinning, or maybe if the drawer opens. Whereas, an
    old IDE hard drive with the ribbon cable unconnected, you can connect
    that to your Molex, and get a 12V @ 0.6A kind of load. Better than
    nothing. The hard drive draws up to 12V @ 3A during spinup, but
    levels off at a lower current level. The 3.5" hard drives are the ones
    that use 12V for the motor. Make sure the supply can tolerate a
    3A load on 12V.

    It could be the 12V is out of spec. Note that the "feedback" system
    in cheap PSUs is crazy, in that one feedback is used for everything.
    If 5V is heavily loaded, the supply "puts more umpf into it",
    and the 5V rises back to nominal, while the 12V overshoots a bit
    (rises to 12.6V). This is referred to as "cross loading". Only
    a few supplies, used separate circuits for each rail, feedback
    per rail, and do tight tracking (no overshoot). The voltages
    are related by transformer turns ratio, which is why the outputs
    track when the outputs are turned up.

    If I had to guess, your 12V output is probably a bit weak, and
    the feedback went to the wall and it didn't help. If I was
    sitting there, I'd have out my clamp-on DC ammeter (Hall probe
    type), to measure the actual current, and check for an overload
    caused by a motherboard defect. It's not always the
    power supply fault, but your "LL" suggests all is not
    right there. With the motherboard disconnected, it hasn't
    returned to normal.

    Now that you've seen the label on the supply, maybe
    you can order a new one. Usually the label has a
    complete breakdown of 3.3V @ X amps, 5V @ Y amps,
    12V @ Z amps. And you can find something that meets or
    exceeds each rail.

    Paul
     
    Paul, Dec 14, 2014
    #5
  6. Paul

    Al Drake Guest

    Thanks again Paul. I'll order one tonight. I saw plenty for cheap. I
    will however, use a volt meter like you suggest just to make sure.

    Regards,

    Al.
     
    Al Drake, Dec 15, 2014
    #6
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