Just as an FYI... I have found the following two PSU's currently being sold that still support a -5V line on the ATX 20-pin connector. I'm sure there are others out there. This was just a quick pass through NewEgg to see what was available and somewhat cheap. You should be able to find these at your favorite online computer shops without too much trouble.

StarTech ATXPOWER300 300W ATX Power Supply
RAIDMAX RX-380K 380W ATX12V Power Supply EDIT: DO NOT BUY. NEWEGG PHOTO IS OLD. NO LONGER SUPPORTS -5V.

EDIT: Update to available -5V supplies.

StarTech also still makes an AT power supply:

http://www.amazon.com/StarTech-com-Replacemen … /dp/B00005133U/

By definition, all AT power supplies will include the -5V line. But it's good to know that they are still available. (I actually have one of those star tech AT PSU's as a spare / testbed PSU).

OFF:
would that StarTech PSU work on this config?
-Pentium MMX 233MHz
-128mb sdram
-3DFX VOODOO 3000 AGP
-Maxi Sound Game Theater 64 (ISA)
-Ethernet PCI + USB2.0 PCI
-80GB HDD
-DVD-ROM
turbo display (I did some tricky connection, so I Took the usb card and used his internal usb to give the display energy since my motherboard doesn't support it '-'

well, that's all 😀

I have a good PSU on this device, it has like 10 years or more that I have it, it worked just fine on a pentium 3 1GHz, but the problem is:
1)ATX (Power on/Off on this case is useless '-')
2)220v only (So I always need a really big transform to use the computer '-')
But at least it has a cool feature on that atx psu, It can stay on by one second without energy thanks to a big transformer or battery inside of it 😳

ibm5155 wrote:

OFF:
would that StarTech PSU work on this config?

I found an older thread where you were talking about some of this. Since you have an AT case and an AT power supply currently. I would recommend staying with that configuration, personally.

If you think your PSU is flaky. You could buy the StarTech AT PSU new. I think that's a better option than ATX, even if your motherboard can technically accept an ATX PSU.

The AT psu is now gone, since months of research I concluded that the AT PSU was the cause of all my problens.
So for now I'm only using the ATX PSU since it's the only thing I have for now '-', the motherboard is good, it support ATX and AT connection...

Fun fact: I discovered that for somehow, If I had a flash drive pluged in usb 2.0 board, I noted a huge performance drop (27fps on quake 2, 40fps on quake 2 without the flash drive), but for some reason, the same flash drive on the internal usb 1.1 wouldn't cause any fps drop (and others usb things wouldn't actually touch the fps)...

1 year of hard research was actually good, I ended up making a kind of ms-dos text engine 😁

http://www.flaterco.com/kb/PC_incompatible.html

Since pin B5 is not connected on Sound Blaster Pro 2 (CT1600) that should suggest that this card does not need -5v

https://www.vogonswiki.com/index.php/File:Cre … 2_underside.jpg

is nobody selling those at to atx adapters anymore bought 2 of them like 2 years ago with -5 and a dummy load works perfect in my p1 and p3
the seller stopt making them

scroeffie wrote on 2020-12-02, 10:52:

is nobody selling those at to atx adapters anymore bought 2 of them like 2 years ago with -5 and a dummy load works perfect in my p1 and p3
the seller stopt making them

If you don't mind a somewhat more expensive (but fancier and safer) solution, search for the "ATX2AT" project.

I just got a YMF719 which seems to have the 5th pin and I am not sure if it requires -5V for proper operation. Please see the images below. Could someone please let me know if this requires -5V? If so I may have to return this card as I don't have an AT PSU.

stealthjoe wrote on 2024-03-28, 07:12:

I just got a YMF719 which seems to have the 5th pin and I am not sure if it requires -5V for proper operation. Please see the images below. Could someone please let me know if this requires -5V? If so I may have to return this card as I don't have an AT PSU.

No, that card does not require -5V. The pad is there, yes, but there are no traces coming out of it.

TheMobRules wrote on 2024-03-28, 08:03:

stealthjoe wrote on 2024-03-28, 07:12:

I just got a YMF719 which seems to have the 5th pin and I am not sure if it requires -5V for proper operation. Please see the images below. Could someone please let me know if this requires -5V? If so I may have to return this card as I don't have an AT PSU.

No, that card does not require -5V. The pad is there, yes, but there are no traces coming out of it.

Thanks a ton for confirming! Feeling at ease now 😊

I have an OPTi 82C925 that requires negative 5 volts (-5v) so the MIDI can work correctly like the others mentioned in this post.

This card marked (EPC-OPID9251) uses a TL074 opamp that handles both the MIDI and wavetable audio path and needs +/-5v to amplify the audio correctly. The wave output is fine but the MIDI sounds very quiet and clipped/distorted with the opamp missing the negative rail. I learned of this when I tried my wavetable Pi card.

My solution was to add a negative voltage regulator (LM2990T in my case), to the lower right corner. The tab on this and most 7905 regulators is INPUT meaning the tab will be -12V so remember to isolate with tape! Everything works after that. One issue may be leaving the -5V pin on the ISA card intact. Meaning this un-heatsinked regulator is pushing -5V back onto the motherboard/backplane. In my case I only have one ISA card in the system so probably not an issue.

So far, some sound and network cards have been mentioned here.

But do any of you happen to know if ISA graphics cards commonly required negative voltages as well? I couldn't find an answer online.

I'm experimenting with a half-size ISA SBC card, plugged into a passive (unpowered) ISA riser card I had lying around that was left over from some proprietary PC.

In this setup, I tried both an ATI VGA Wonder rev 2 card and a Hercules Graphics Card clone, and neither card seem to work in this configuration. Although the SBC does seem to detect the HGC card at least partially on boot, the monochrome monitor (and IBM 5151) doesn't power on, like it did when I tried both these cards on another system with the same monitor hooked up to them.

The riser does not have an AT or ATX connector, so the SBC is powering the riser (and through that the graphics card) from a single molex connector connected to the SBC. I checked one of the ISA slots on the riser with a volt meter while the system was running, and only the positive voltages (+5V on pin 3 and +12V on pin 9) are working, whereas the negative voltages (-5V on pin 5 and -12V on pin 7) are not. Which makes complete sense, since the molex connector doesn't supply those to the SBC.

But could it also be a matter of the ISA bus being underpowered in this setup? If so, why doesn't the SBC itself become unstable, since it has to share its power with the bus?

TL;DR: is a dependency on negative voltages typical for ISA graphics cards, or is there perhaps something else going on with my (not very typical) setup?

Thanks.

digger wrote on 2024-08-12, 21:02:

So far, some sound and network cards have been mentioned here. […]
Show full quote

So far, some sound and network cards have been mentioned here.

But do any of you happen to know if ISA graphics cards commonly required negative voltages as well? I couldn't find an answer online.

I'm experimenting with a half-size ISA SBC card, plugged into a passive (unpowered) ISA riser card I had lying around that was left over from some proprietary PC.

In this setup, I tried both an ATI VGA Wonder rev 2 card and a Hercules Graphics Card clone, and neither card seem to work in this configuration. Although the SBC does seem to detect the HGC card at least partially on boot, the monochrome monitor (and IBM 5151) doesn't power on, like it did when I tried both these cards on another system with the same monitor hooked up to them.

The riser does not have an AT or ATX connector, so the SBC is powering the riser (and through that the graphics card) from a single molex connector connected to the SBC. I checked one of the ISA slots on the riser with a volt meter while the system was running, and only the positive voltages (+5V on pin 3 and +12V on pin 9) are working, whereas the negative voltages (-5V on pin 5 and -12V on pin 7) are not. Which makes complete sense, since the molex connector doesn't supply those to the SBC.

But could it also be a matter of the ISA bus being underpowered in this setup? If so, why doesn't the SBC itself become unstable, since it has to share its power with the bus?

TL;DR: is a dependency on negative voltages typical for ISA graphics cards, or is there perhaps something else going on with my (not very typical) setup?

Thanks.

Ah, super interesting! I'm also messing with some SBCs and various cards.

What SBC are you using? What backplane type are you using?

I'm limited with my knowledge of negative voltage requirements, but your statement is accurate. Most SBCs I've seem can be dual powered by either a direct connection, (4 - 6pin) or from the bus. In my case, my backplanes are externally powered and provide -12v to the bus. Powering the SBC directly allows on +12v and +5v (+3.3v with the Allen Bradley 6 pin) and the daughter cards seem to run fine.

I don't have any old ISA graphics cards to test so I can't comment in that case. However, depending on which SBC type you're using, there are at least 3 +5v pins and 1 +12v pin on the ISA standard. Pushing current back though the ISA pins may be suseptible to weak connections causing a voltage drop on the daughter cards. The SBC might be fine, but the voltage through the edge connector may be suffering from corrosion or weak metal yo metal contact.

It might be tricky to easily inject -12v and -5v onto a passive backplane unless you have free ISA slots. That's assuming it's needed for old ISA graphics. It might be possible to piggy back a negative voltage regulator onto the card but would take some planning.