Some of the ATX to AT adapters include a small linear regulator to generate the -5v rail, and that's an option to consider -- the current draw on -5v is minimal, so there's no need for anything fancy. (I believe they use something basic like a 7805 hooked up to the -12v rail?)

Otherwise go search for the absolute oldest ATX cases you can find... any motherboard that still included ISA slots would expect the ATX PSU to supply -5v.

I managed to find an ATX PSU with -5v by digging through a mountain of power supplies at one of my local e-waste recycling places. Most lacked -5v but there were a handful that had it. At least the presence/lack of -5v is clearly indicated on the PSU label.

My mobo IS an ATX motherboard, only has the 20 pins instead of 24 though. So I couldn't use AT. Unless I get one of those and then convert it back to ATX 🤣

Using the -12V line and a L7905 (T220 -5V Linear regulator IC) would work well. As for ATX supplies, most all new ones do not have -5v, you need to look for older ones but they most likely need re-capping.
An Enlight HPC-300-101 (300w ATX) has -5v, as do older Antec True Power 480 models...

There are a few ATX PSUs with -5V on that auction site we don't discuss here 😀 I don't think any are new though.

I went through my ATX PSUs a few years ago to check this. The following all have -5V:

Cortek LC-300
CWT CWT-350BDP
Delta DPS-260EB-2A
Enermax EG365P-VE(FM)
Enermax EG465P-VE(FM)
Enermax EG651P-VE(FMA)
Q-TEC Model 13492
Q-Tech QT-02350G
Sparkle FSP235-60GI

You can also solder LM2662 module to +5V line, it will turn it into -5V. It should provide 100mA. Here i soldered it directly to pico psu, I also added a protective Schottky diode on -5v output (it may drop the voltage a little as side effect), to minimize risk of passing positive voltage in case of failure.

Camtheman wrote on 2020-10-15, 23:03:

My mobo IS an ATX motherboard, only has the 20 pins instead of 24 though. So I couldn't use AT. Unless I get one of those and then convert it back to ATX 🤣

Not that crazy an idea given the lack of other viable options.

There are a few newly made industrial PSUs with a negative 5V rail, though these might be a bit tricky to find

Camtheman wrote on 2020-10-15, 22:16:

Anyone got any hot leads on one of these, preferably as cheap as possible?

Or a way to mod an ATX PSU with the missing pin to supplying -5v? (Soldering is fine by me)

And yes I do need the -5v, for a GUS Max 2.1

If you do not mind me asking, how did you come to the conclusion that a GUS MAX 2.1 requires -5V ? AFAIK, it does not .

According to https://upload.wikimedia.org/wikipedia/common … SA_Bus_pins.svg , -5V is on pin B5 of the ISA connector and if you look at a photo of a GUS MAX 2.1 , pin B5 is not connected to anything . https://i.imgur.com/wuLUwhf.jpg . Unless your card is different

Additionally no GUS cards are listed here : ISA Cards & Devices Requiring -5V

darry wrote on 2020-10-16, 05:22:

If you do not mind me asking, how did you come to the conclusion that a GUS MAX 2.1 requires -5V ? AFAIK, it does not . […]
Show full quote

Camtheman wrote on 2020-10-15, 22:16:

Anyone got any hot leads on one of these, preferably as cheap as possible?

Or a way to mod an ATX PSU with the missing pin to supplying -5v? (Soldering is fine by me)

And yes I do need the -5v, for a GUS Max 2.1

If you do not mind me asking, how did you come to the conclusion that a GUS MAX 2.1 requires -5V ? AFAIK, it does not .

According to https://upload.wikimedia.org/wikipedia/common … SA_Bus_pins.svg , -5V is on pin B5 of the ISA connector and if you look at a photo of a GUS MAX 2.1 , pin B5 is not connected to anything . https://i.imgur.com/wuLUwhf.jpg . Unless your card is different

Additionally no GUS cards are listed here : ISA Cards & Devices Requiring -5V

Well it turns out i'm a massive derp. I have a ESS AudioDrive 1868f, it has a bunch of missing pins on the ISA connector. The gus has all of them. I also didn't see the GUS appear in the BIOS initialization. It's not a PnP card, of course it won't show there. From all this I assumed it needed -5v to function.

I fiddled around with some IRQs and now the GUS works on the modern Corsair PSU.

Although I think the AudioDrive with the DreamBlaster X2 sounds better.

Camtheman wrote on 2020-11-27, 06:09:

Well it turns out i'm a massive derp. I have a ESS AudioDrive 1868f, it has a bunch of missing pins on the ISA connector. The gu […]
Show full quote

darry wrote on 2020-10-16, 05:22:

If you do not mind me asking, how did you come to the conclusion that a GUS MAX 2.1 requires -5V ? AFAIK, it does not . […]
Show full quote

Camtheman wrote on 2020-10-15, 22:16:

Anyone got any hot leads on one of these, preferably as cheap as possible?

Or a way to mod an ATX PSU with the missing pin to supplying -5v? (Soldering is fine by me)

And yes I do need the -5v, for a GUS Max 2.1

If you do not mind me asking, how did you come to the conclusion that a GUS MAX 2.1 requires -5V ? AFAIK, it does not .

According to https://upload.wikimedia.org/wikipedia/common … SA_Bus_pins.svg , -5V is on pin B5 of the ISA connector and if you look at a photo of a GUS MAX 2.1 , pin B5 is not connected to anything . https://i.imgur.com/wuLUwhf.jpg . Unless your card is different

Additionally no GUS cards are listed here : ISA Cards & Devices Requiring -5V

Well it turns out i'm a massive derp. I have a ESS AudioDrive 1868f, it has a bunch of missing pins on the ISA connector. The gus has all of them. I also didn't see the GUS appear in the BIOS initialization. It's not a PnP card, of course it won't show there. From all this I assumed it needed -5v to function.

I fiddled around with some IRQs and now the GUS works on the modern Corsair PSU.

Although I think the AudioDrive with the DreamBlaster X2 sounds better.

Glad that you got it working . IMHO, the GUS patchset is quite decent but an FX engine on the GUS would have helped the patchset really shine. The company that made that patchset has continued working on it for years. The most recent iteration in soundfont form (for Creative cards and SF2 compatible softsynths), is one of my favorites on my AWE64 and it is only 4MB in size! Here is some info, if you are curious : http://www.voicecrystal.com/services.htm

The X2 with Buran soundbanks is very good indeed and is better than MIDI on the GUS in nearly all cases, subjectively speaking. The X2 can't do tracker stuff, though, which is the main reason to have a GUS, IMHO . Unfortunately, not many games support the GUS in that way. For non gaming tracker based music playback, the software mixing and interpolation engine in Open Cubic Player is great and works with lots of ISA cards, including ESS based ones .

Yeah, well, you weren’t supposed to use MIDI anyway, the driver support was more meant as backward compatibility. You were supposed to upload your own sound effects to the RAM of the card. But in the end, MIDI was so well and firmly established that the whole idea of a Paula chip on steroids was a commercial failure and the GUS almost always was running in some kind of compromised compatibility mode and not in the native mode it was designed for 😐

adalbert wrote on 2020-10-16, 01:16:

You can also solder LM2662 module to +5V line, it will turn it into -5V. It should provide 100mA. Here i soldered it directly to pico psu, I also added a protective Schottky diode on -5v output (it may drop the voltage a little as side effect), to minimize risk of passing positive voltage in case of failure.

Old thread resurrection!

What a great I idea! Just ordered a little LM2662 module to try the same for an unusual IBM PS/2 E I have with a failed PSU! Will report back when the parts are here to say if it worked.

Steve .. are you by chance a Necromancer...2011 was quite the resurrection !