dual psu issue! hot wires!

Discussion in 'Troubleshooting Help' started by Luke212, Jul 23, 2017.

  1. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    I have two big ATX power supplies and I am trying to link them together and to start at the same time. so i have a dual ATX adapter. eg. https://www.ebay.com.au/i/263065818818?chn=ps&dispItem=1

    the secondary psu is just linked to some expansion board and gpus.

    this is on a Tyan server motherboard. Anyway, when I start the motherboard, i get a TICK TICK TICK sound inside the secondary PSU. and the fan doesnt spin. I thought maybe it was a bad PSU so i swapped it for another one. and it makes the same noise.

    I noticed when i held the two wires of the dual-psu adapter the wires were hot! but from what i understand the two wires (green black) are just signal wires. So how the fuck are the getting hot?
     
    Last edited: Jul 23, 2017
  2. mad_mic3

    mad_mic3 Member

    Joined:
    Jan 18, 2009
    Messages:
    1,862
    Location:
    Nulkaba
    maybe green is a sense wire, black is earth?????
     
  3. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    yeah thats what i was saying. so why is it hot? did the atx adapter company fuck up? seems unlikely.

    now im worried it was pumping amps in to my expensive psus and damaging them :((
     
  4. terrastrife

    terrastrife Member

    Joined:
    Jun 2, 2006
    Messages:
    18,127
    Location:
    ADL/SA The Monopoly State
    Not hard to check the pin out to confirm.
    Second PSU may not have enough minor rail load if it's not a DC-DC PSU.
     
  5. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    The pins on the adapter look ok.

    what is a DC-DC PSU? i tried 2 1000W psus with the same noises. plenty of power.

    it might be this expansion board giving the problem (TK025 Dual Graphics Riser for T7400 http://www.ebay.co.uk/itm/NEW-Dell-...TK025-TK016-/231890569721?hash=item35fdc149f9 see photos). I connected the second psu to the below expansion board with an EPS cpu connector. But maybe its not a standard EPS?

    http://en.community.dell.com/support-forums/desktop/f/3514/t/19404819

    how is your pin analysis here? im not sure about this stuff:

    reading this: does it mean its PCIE pins but in an EPS plug?

    http://en.community.dell.com/support-forums/desktop/f/3514/t/19404819

    and someone talking about a custom harness:

    http://en.community.dell.com/support-forums/desktop/f/3514/t/19404819
    last post.
     
    Last edited: Jul 24, 2017
  6. _zak

    _zak Member

    Joined:
    Oct 12, 2009
    Messages:
    310
    Is the primary PSU connected to anything in common with the secondary PSU? That's likely to cause bad things to happen, and could occur if the primary PSU is supplying power to the PCI-E slot that contains graphics cards you're powering with the secondary.

    The best bet for working out the voltages present on the riser card's connector is to follow the traces from the pins with a multimeter. In the pictures, it looks like the PCB has some pretty hefty ground planes, so you should be able to trace those fairly easily. Once you work out which three or four pins are tied to ground, you'll have a bit more information to work with.

    That all said, that last comment you've quoted makes me think that you may well have a hell of a time getting the riser card to work. From the eBay picture, the connector configuration is the same as an EPS connector, but if there is a 3.3 V line in Dell's version, the price of failure is releasing smoke - both PCI-E and EPS connections only run 12 V and ground. The only way to be really sure is to get a Dell PSU and check what voltages are present, but I'm guessing that's not an option.
     
  7. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    thanks for the info. i assume the dell psu wouldnt have the correct plug anyway because the riser probably comes with an assembly kit with the correct adapter. and if that were the case then its unlikely to be a 3.3V simply because EPS does not provide it.

    So how do i measure voltages on the plug? Do I have to turn it on? that seems not a good idea given the noises I am getting and potentially damaged hundreds of $$$ already :( sorry i dont know how to measure volts im a n00b in this regard!
     
  8. _zak

    _zak Member

    Joined:
    Oct 12, 2009
    Messages:
    310
    Don't rule out the possibility that Dell is using the physical EPS plug with different voltages running to it. It wouldn't be the first time that they'd used proprietary pinouts on their power supplies. The pictures in the Dell thread you linked show four black wires (likely ground), two yellow (likely +12 V), and two orange (which is usually 3.3 V). The reason I think it's likely is not just because there are orange cables on what appears to be the genuine connector - PCI-E slots have to supply 3.3 V, and there's no reason for the riser card not to source it from the PSU.

    To actually know what the riser card requires, you'd have to find a known-compatible power supply for the riser card, turn it on, and put a multimeter across each of the pins. I'm guessing this isn't something you're able to do though, so guesswork it'll have to be.

    This may explain why the PSUs are acting weirdly. The EPS connector looks like this:
    Code:
     |clip|
    5|oxxo|8
    1|xoox|4
    Standard EPS pinout: pins 1-4: ground; pins 5-8: +12 V
    Dell's apparent pinout (based on colours): pin 1: ground; pin 2-3: +12 V; pin 4: 3.3 V; pin 5-7: ground; pin 8: 3.3 V.

    So if the riser card sources some power from the motherboard's PCI-E slot, you were basically shorting the secondary PSU's +12 V and 3.3 V line to the primary PSU's ground, tying their grounds together, and trying to push 12 V into the primary PSU's 3.3 V line.

    Personally, I'd be looking for other ways to expand one PCI-E slot into two.
     
  9. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    The amazing thing about these risers is the PLX chip. it will work on any system. most ordinary risers rely on bifurcation on the motherboard, and only supermicro mbs do this.
     
  10. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    http://downloads.dell.com/manuals/a...tation/precision-t7400_user's guide_en-us.pdf

    ok here there are two 8 pin plugs that come with the original tower:

    DC Power Connector P19:

    1 COM Black
    2 12 VD Yellow/White
    3 12 VD Yellow/White
    4 3.3 V Orange
    5 COM Black
    6 COM Black
    7 COM Black
    8 3.3 V Orange

    DC Power Connector P24:

    1 12 VE Blue/Yellow
    2 12 VE Blue/Yellow
    3 12 VE Blue/Yellow
    4 COM Black
    5 COM Black
    6 COM Black
    7 COM Black
    8 COM Black

    so im looking at the P19 right? by the way does that P24 look like a nomal EPS?
     
  11. _zak

    _zak Member

    Joined:
    Oct 12, 2009
    Messages:
    310
    P19 sounds like the connector - it definitely matches the pinout of the one on the community site.

    P24 isn't a standard EPS cable; as I posted before, the standard pinout is to have the first four pins connected to ground. P24 is (partially) reversed.
     
  12. ir0nhide

    ir0nhide Member

    Joined:
    Oct 24, 2003
    Messages:
    3,739
    Location:
    Adelaide
    *subscribes to hear about results from electrical fire*
     
  13. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    im really pissed about this.

    so how do i get these other rail voltages? Do I just make a custom plug to pull from other plugs in to one plug? i dont think it will be super high current. It will be running two gpus, but they will pull current from other power.

    but what wire should i use? find some existing 3.3 /5 wires and re-use them maybe?
     
  14. _zak

    _zak Member

    Joined:
    Oct 12, 2009
    Messages:
    310
    The obvious choice would be SATA power connectors, as they (usually) have one each of 3.3 V, 5 V and 12 V as well as two grounds. Depinning two of them and putting the pins into the right spots on an unused EPS plug should work well.

    Don't forget a label on the modified EPS plug so you don't fry a motherboard in the future.
     
  15. Luke212

    Luke212 Member

    Joined:
    Feb 26, 2003
    Messages:
    9,074
    Location:
    Sydney
    So i destroyed a 1500W platinum PSU and a 1050W PSU

    unreal. thank you dell for sucking ass and making weird cables.
     
  16. HobartTas

    HobartTas Member

    Joined:
    Jun 22, 2006
    Messages:
    556
    Easiest way to do this is simply to buy power supplies that have this capability already engineered into their design like the Antec High Current Pro Platinum series which have "OC Linkā„¢ - Allows 2 HCP Platinums to work in tandem to power the most demanding systems" and should be very high quality as they are made by Delta Electronics and linking two of the 1300W units would give you 2600W to play with. I bought two of the 850W units for the purpose of perhaps later on making a server with about 20-24 hard drives in it as I don't want to run that many hard drives with just one power supply.
     
  17. schmoove

    schmoove Member

    Joined:
    Oct 13, 2006
    Messages:
    634
    Location:
    Asia
    Dell and HP are famous for using non-standard pinouts.
    I've seen a pal of mine blow a psu due to this very issue.
    Would never buy anything made by these two companies due to absurd business practices such as these.
     
  18. Benergy

    Benergy New Member

    Joined:
    Sep 25, 2017
    Messages:
    18
    Location:
    Queensland
    Good morning, Luke212.

    Sorry to hear about your PSU being destroyed by stupid non-standard pinouts.

    Back in 2011 I was ordering components for an Intel 2600K build and I accidentally ordered the wrong PSU. I didn't read the listing closely enough, I thought I'd scored a cheap Thermaltake 650W PSU (it was $89 at PCCG).

    As it turned out, I'd actually ordered a 'VGA' PSU - basically an auxillary PSU which piggy-backs off the primary PSU.

    I'm not sure if you can still get these but if it's big video cards you're trying to power, one of these might suit your needs. Mine installed in 2 x 5.25" CD/DVD bays from memory and included the 'piggy-back' cable too.

    Looks like Thermaltake did a 650W dual 5.25" bay model and a 450W single 5.25" bay model.

    Link 1:
    https://www.techpowerup.com/46651/thermaltake-power-express-450w-and-650w-vga-power-supply

    Link 2:
    https://www.pccasegear.com/products/7163/thermaltake-toughpower-express-650w-vga-power-supply

    Ben
     

Share This Page