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I need expert help. I have an old Lenovo C540 AiO desktop that I am trying to salvage. This model is prone to a failure in the SATA power cable, at the HDD connector end. I have found video guides on how to create your own power cable using a spare SATA power cable and the mini motherboard connector from the original cable.

https://www.youtube.com/watch?v=ysX7qb2MFMo

enter image description here

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Unfortuntely, I cut off the original motherboard connector end before I made note of which black connects to which black end to end.

The guy who made the video told me that matching the black does not matter. This seems correct, but I want to get this right and could use a second opinion.

I have looked at pinouts on the standard SATA end, and the blank are just labeled as "GND" but the 11 pin is labeled as "Staggered spinup/activity". I can find no pinout for the motherboard connector.

I have tried to contact a seller on ebay who has torn into this model before to see if he could confirm the original design, but he has not replied since our original contact.

Can anyone confirm that I can connect either black to either black? I don't really understand why they don't just put them in the same order on both ends to avoid confusion.

Thanks.

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    \$\begingroup\$ As I recall BLK=0V , Red=5V, Yellow = 12V , Grey =? \$\endgroup\$ – Tony Stewart EE75 Aug 14 '20 at 14:50
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    \$\begingroup\$ The question is do the two blacks have to match up in any way from end to end? \$\endgroup\$ – user786028 Aug 14 '20 at 14:58
  • \$\begingroup\$ @user786028 The two blacks do not have to match up in any way on those connectors. Please see Molex to SATA power adapter from a Cooler Master modular PSU? \$\endgroup\$ – Andrew Morton Aug 14 '20 at 15:24
  • \$\begingroup\$ All BLK=0V same \$\endgroup\$ – Tony Stewart EE75 Aug 14 '20 at 16:41
  • \$\begingroup\$ Very rare use sequence option to prevent 12V surge with many drives \$\endgroup\$ – Tony Stewart EE75 Aug 14 '20 at 16:43
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https://en.wikipedia.org/wiki/Molex_connector

Why does the SATA power connector have so many pins?

sata power connector

black = ground red = +5v yellow = +12v

the answer is basically in your pics.

for white molex, the black next to the yellow is the ground for the +12vdc circuit. And the black next to the +5vdc red is ground for that.

With the black SATA connector, black between yellow and red goes to the yellow +12vdc circuit. The gray sata wire, on the sata power connector, is either a hard drive spin up signal wire or 3.3vdc power, there's no significant current on the gray wire so it shares ground with the red +5vdc.

Can anyone confirm that I can connect either black to either black? I don't really understand why they don't just put them in the same order on both ends to avoid confusion.

The SATA power connector has 15 total pins, but you can't put X wattage through one 1mm wide pin in the connector so there are numerous pins to provide the area needed given the form factor of that connector.

If you criss cross the ground wires then what would happen?

I don't know I can only speculate.

But in electrical engineering terms would high current +12vdc return to the power supply on what would be the +5vdc rail before ground DC ground becomes common with the PSU? I think if you answer that question then you would know for sure if criss crossing the ground wires is something not to do. If you're connecting just one hard drive, especially an SSD which uses like 2 watts, I doubt there would be any harm. The worry would be if some high power device was being powered. In any case, I would not criss cross those two black grounds and given what I described above hopefully it's now clear that if your messing with it there should be no reason now you would end up criss crossing the grounds.

do this: dothis

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  • \$\begingroup\$ I think this clears it up. To recap, the black next to yellow on the SATA end should connect to the black next to yellow on the white molex end (i was not sure if this was technically molex). The black next to red on the SATA end connects to the black next to red on the white end. While this certainly seems logical, when I tried to follow the wires in this photo of a replacement cable, it seemed like this was not the case, but I admit that the wires are not easy to follow in this image. amazon.com/gp/product/B06VYGTLS8/ref=ask_ql_qh_dp_hza \$\endgroup\$ – user786028 Aug 14 '20 at 15:39
  • \$\begingroup\$ And the intent was to indeed install an SSD, but I will most likely start with a platter drive for some initial testing. \$\endgroup\$ – user786028 Aug 14 '20 at 15:40
  • \$\begingroup\$ yes just think simply, closest black to a color goes with that color when dealing with the cables such that a black should never have to jump over a color to pair with some color. \$\endgroup\$ – ron Aug 14 '20 at 15:43
  • \$\begingroup\$ That makes complete sense. I guess I should have just gone with logic rather than trying to trace black wires in a picture where they are constantly overlapping each other. \$\endgroup\$ – user786028 Aug 14 '20 at 15:54

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