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Legacy Power Supply

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  • Power Supplies
  • Legacy
  • Motherboards
  • Components
  • Product
Last response: in Components
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July 2, 2010 1:46:01 PM

Hello Everyone,
I asked a question about large cases not long ago and you were all very helpful, so I have another one for you? Does anyone know where I can purchase a power supply which has a 12 pin connection to the motherboard? The PC is an early P166. I don't really want to change the motherboard as I need the ISA slot and the machine is working fine but the fan in the PSU sounds like it is dying. I have done a bit of digging around and it looks like I can use two 6 pin connectors instead of one 12 but I can't find a PSU with that either. I know the PC is old and rubbish but what it controls isn't and would cost a fortune to upgrade. Cheers

More about : legacy power supply

a b ) Power supply
a c 304 V Motherboard
July 2, 2010 2:04:18 PM

Hi newcomer and welcome to the Tom's hardware forum.

What specific connector do u refer? main connector or 12V connector
a b ) Power supply
July 2, 2010 2:20:19 PM

What do you need the ISA for? I think I might have an old PSU that still works but I threw out a load of old stuff last year so I'm not too sure. What wattage do you need?
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a b V Motherboard
July 2, 2010 4:32:07 PM

ballri said:
Hello Everyone,
I asked a question about large cases not long ago and you were all very helpful, so I have another one for you? Does anyone know where I can purchase a power supply which has a 12 pin connection to the motherboard? The PC is an early P166. I don't really want to change the motherboard as I need the ISA slot and the machine is working fine but the fan in the PSU sounds like it is dying. I have done a bit of digging around and it looks like I can use two 6 pin connectors instead of one 12 but I can't find a PSU with that either. I know the PC is old and rubbish but what it controls isn't and would cost a fortune to upgrade. Cheers


That would be an old AT power supply, and I haven't seen too many of those around. I'd suggest looking for a newer board with ISA slots but takes an ATX power supply connection. There are a lot of Pentium II/III and AMD K6/Athlon boards out there with a 20-pin ATX power supply connection (which is backwards compatible with a modern 24-pin ATX power supply connector) and have ISA slots. I'd suggest looking in the junk pile at a local computer store or on eBay for such a unit.
July 2, 2010 8:20:37 PM

Hi, thanks for your responses. It is the main connector to the motherboard. Yes I think it is an AT power supply, but I am struggling to find one. I think the wattage is only very low probably no more than 250W. The PC is a Pentium 166 mhz I think. I could get another motherboard but I don't have the disks for the software on the hard drive. I could swap the hard-drive but then I might run into issues with what ever drivers are needed for the new motherboard etc. The programme and ISA device both run in DOS and the programme is no longer available from the manufacturer. So, I thought the easiest thing was to get a new power supply with 12 pin connector, or a newer power supply with a 20/24 pin connector and then buy or make a converter from 20/24 to 12 pin. I am struggling even to find pin out diagram however. Any help greatly received and thanks for your responses so far.
July 2, 2010 8:22:41 PM

I have just found this:

Motherboard power connector
Standard AT-style motherboard gets power from the power supply through 12 pin power connector which is typically built from two 6 pin parts. The power connector has four different voltages available. The positive +5V power has lots of current available (typically over 10A), +12V has few amperes. The negative power supplies can supply typically quite limited power (-12V few hundred mA and -5 even less).

1. Power Good (output from PS which tells that output voltages are OK)
2. +5Vdc
3. +12Vdc
4. -12Vdc
5. Ground
6. Ground

7. Ground
8. Ground
9. -5Vdc
10. +5Vdc
11. +5Vdc
12. +5Vdc

Are these outputs all found on a newer 20/24 pin ATX connector?
Cheers
a b V Motherboard
July 2, 2010 9:32:44 PM

ballri said:
I have just found this:

Motherboard power connector
Standard AT-style motherboard gets power from the power supply through 12 pin power connector which is typically built from two 6 pin parts. The power connector has four different voltages available. The positive +5V power has lots of current available (typically over 10A), +12V has few amperes. The negative power supplies can supply typically quite limited power (-12V few hundred mA and -5 even less).

1. Power Good (output from PS which tells that output voltages are OK)
2. +5Vdc
3. +12Vdc
4. -12Vdc
5. Ground
6. Ground

7. Ground
8. Ground
9. -5Vdc
10. +5Vdc
11. +5Vdc
12. +5Vdc

Are these outputs all found on a newer 20/24 pin ATX connector?
Cheers


Yes, the outputs are all there on the newer connector, plus some more for +3.3 VDC. However, you will need to find an older ATX power supply with a 20-pin main connector to get -5 VDC, which your ISA cards may need and more modern PSUs mostly do not provide because newer motherboards do not need it.
July 2, 2010 10:04:00 PM

OK, I understand. I will look out for an older ATX PSU, we may even have one in our stores and then I'll wire on the old plug. Many thanks for your help
July 3, 2010 12:26:03 PM

Thanks JTT283 I have just looked at newegg and that is exactly what I need, what I didn't mention in my previous posts is that I am in the UK. I just checked the newegg website and they don't yet deliver internationally and I haven't found anyone in the UK who can supply one. Thanks
!