Compaq SP750 PSU pinout? \ VOGONS

Compaq SP750 PSU pinout?

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First post, by martin_boro

Posted on 2020-12-22, 15:01

martin_boro Offline

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I have recently bought three bare motherboards with the memory boards, but unfortunately, but unfortunately, they have proprietary power supply connectors. Custom 10 pin and a 20pin, that fits a standard ATX PSU.
I kinda hope, that I might be able to splice something from an standard ATX PSU, but I don't have the pinout.

I did some continuity measuring with a multimeter and came up with this:

The attachment SP750.PNG is no longer available

G is ground, numbers have continuity between each other, ie. 1 to 1 and 2 to 2.
I don't know, what the blanks are, or at least, I don't know where to measure them.

The 10pin looks completely custom, but the 20 pin might just be a standard ATX pinout, if flipped horizontally.
If that is true, that means, that 1 is +5V and 2 is +3.3V.

It could also mean, that the CPUs and maybe even the RAM is running mainly from the 3.3V, which could make using a modern PSU a bit complicated.

Is an adapter like this a viable option, or am I stuck searching for a custom PSU?

Reply 1 of 8, by pentiumspeed

Posted on 2020-12-22, 15:41

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Use ISA bus like from a wiki and use 5V, 12v, -5V and -12V to find all the other pins then you will leave with one pin that are, power good.

By the way, what board this came out of? Photos of board is best.

Cheers,

Great Northern aka Canada.

Reply 2 of 8, by martin_boro

Posted on 2020-12-22, 16:05

martin_boro Offline

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The originally came out of a Compaq/HP SP750 workstation.
Dual Slot 2 + RIMM RAM + AGP + Intel chipset. Pretty cool.

The attachment DSC_7287.JPG is no longer available

It's essentially identical to what is shown on this listing.
I have the memory boards too, but not at hand at the moment.

Also, the board doesn't have any ISA slots.

Reply 3 of 8, by Callahan

Posted on 2020-12-22, 18:43

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These are great mobos 😉
https://pinouts.ru/Power/compaq_psu_pinout.shtml
CPUs (Xeons) are feeded directly from 12V and 5V rails. SP750 uses a 5V/12V Xeons with own on-cartridge VRMs

Look for this PSU:

Cpq: ap550(2x1G/256k), sp750(2x900/2MB), 5100(2xpII300)
TD-30 2xP166 NT 3.51
HP Vectra XU 6/200 2x PIIOD 512MB FPM Banshee
Super S2DG2@550/2MB SCSI 15k V5 5500
P4T533-C P4 3,06 Ti4600
Dell T700r @P3-700 V3 3500
PR440FX-2x PIIOD Voodoo 4500 PCI r320 CT1920

Reply 4 of 8, by martin_boro

Posted on 2020-12-23, 15:02

martin_boro Offline

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Callahan wrote on 2020-12-22, 18:43:

https://pinouts.ru/Power/compaq_psu_pinout.shtml

That's actually pretty cool. If i understand correctly, all I need to do, is invert the PS_ON and somehow come up with 3.3VSB.
The 10pin can be made with a ATX 8pin + ground pin + 5V?

Does this make any sense?

Reply 5 of 8, by Callahan

Posted on 2020-12-23, 18:14

Callahan Offline

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All i can do for now is just these pics of power connectors.
Check colours with pinout.ru
I don’t have a multimeter right now.

Reply 6 of 8, by martin_boro

Posted on 2020-12-24, 15:24

martin_boro Offline

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Thanks for the photos.
As it turned out, I just bought some more SP750 components from the same seller, probably from the same machines.

Before I finalize the order, is there anything else I'd need to get at least one working?

Reply 7 of 8, by PC Hoarder Patrol

Posted on 2020-12-24, 21:33

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Have you reviewed the Maintenance & Service Manual ?

https://www.manualslib.com/manual/276084/Hp-C … -Compaq%20SP750

I'd be thinking at least -

- processors with their attached heatsink / mounting cartridge

- processor cage with additional cooling

- sufficient RDRAM RIMMs (PC600 / PC800, but don't mix speeds) to populate at least 1 of the 2 channels, so 2 matching RIMMs + 2 CRIMMs (already present)

Reply 8 of 8, by Callahan

Posted on 2020-12-24, 22:29

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Only Cascades Xeons with on-cartridge vrm will work. FSB 100 or 133 MHz. Cache size doesn’t matter. Cascades-2M even works.
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