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Thread: PSU for 6000HD

  1. #1
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    Default PSU for 6000HD

    Is the Meanwell RQ-125D a suitable replacement for the 6000HD? If not, what would be a good replacment?

    I would also need to figure out the wiring scheme, but I'm guessing that's around here somewhere if I poke around...

  2. #2
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    The RQ-125D is probably a bit weak on the 5V line to handle a fully populated 6000HD. There is ongoing evaluation work on using the Maanwell MPQ-200D. This is an open-frame medical equipment grade supply that meets the current requirements for all voltages AND it meets the noise requirements specified by Tandy for the 6000's power supply.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  3. #3
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    Maanwell.... argh, should be Meanwell.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  4. #4

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    I'm planning to just use a cheap/free ATX supply when/if I put the 68k board in my Model II. You can wire them to be "always on", and then interrupt the mains power with the original power switch, rather than having to use a momentary pushbutton-type power switch.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  5. #5
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    You'll need a DC-DC converter to generate 24V if you want to use the original thinline 8 inch drives, for the OP's 6000.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  6. #6
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    you've got a nice machine. why not do it right? you can't run it from 2 supplies, so you're saying if you want to run the 68K boards, you'll disconnect one and connect the other?

  7. #7

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    Quote Originally Posted by lowen View Post
    You'll need a DC-DC converter to generate 24V if you want to use the original thinline 8 inch drives, for the OP's 6000.
    Oh yeah, boo, I forgot about that 24v rail for the disk drive. A DC-DC converter is a good idea for that, though.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  8. #8
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    One well-tested option for generating the 24V is DBit's FDDC: http://www.dbit.com/fddc.html

    This solution does the power-on functionality for you. But, $10 more gets you the MPQ-200D.......

    You'll also need to tap the -12V from the main ATX connector. Not sure how much -12V the II/16 or 12/16B/6000 need; for an ATX PC motherboard the need is very small, just for RS-232 mostly; the II series have 4116 DRAM chips as well as RS-232 interfaces.... The -12V is actually a critical voltage for this series.

    Compare your ATX supply's specifications with the Astec supply used in the II and make sure all rails are better than the original supply, and that the noise rating is better, too. And, while most quality non-cheap ATX supplies don't have a minimum load for the 3.3V rail, you'll want to double check, and you might even want to load it a bit.

    And then there is the voltage sequencing requirement for those 4116 DRAM chips. You'll want to check your ATX supply for correct sequence, using the 4116 datasheet as reference.

    Otherwise you'll be disappointed with the results. With faulty sequencing you can destroy 4116 chips, too.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  9. #9
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    Quote Originally Posted by lowen View Post
    The RQ-125D is probably a bit weak on the 5V line to handle a fully populated 6000HD. There is ongoing evaluation work on using the Maanwell MPQ-200D. This is an open-frame medical equipment grade supply that meets the current requirements for all voltages AND it meets the noise requirements specified by Tandy for the 6000's power supply.
    Where can I follow along with this evaluation? The 6000HD I have would power up when I got it. However, after sitting for ~6 months when powered up, the fan and drives will spin up, but no activity other than that. I have not opened it up to do any diagnosis, but after having dealt with old PSUs in the past, I'm almost at the point where I just want to replace with something reliable and get on with life.

    If anyone has suggestions on what I should check when the hood is open, I'm all ears.

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