My big 'ol Ensoniq Soundscape cards don't work without -5v. It's not really hard to find a -5v equipped ATX PSU. That rail is often available on the ~300W PSUs out there (just look at the PSU label for it.)

for example,
http://www.newegg.com/Product/Product.aspx?It … N82E16817152019
and
http://www.newegg.com/Product/Product.aspx?It … N82E16817182006

Thanks for the info, I get what you mean.

I had an LAPC-I once upon a time ago, put it in a ASUS P2B and it worked just fine without fiddling with ISA settings. I wouldn't worry about 4.77MHz.

If no other option exists, you can use a 7905 Voltage Converter to derive -5v from -12v.

If an ISA card requires -5v, and the PSU that you use does not supply this type of voltage, what happens? Does the PC fail to boot? Or does the ISA card in question not function correctly?

Thanks.

Fair enough.

I just changed the PSU which has a -5v output and now the LAPC-I works!(Thanks, swaaye & Great Hierophant).

This is the fastest ISA based system that I have tested the LAPC-I on :

DFI 6AC1 Motherboard
256MB PC133 RAM,
1GHz PIII CPU (Socket 370)
AWE32 3980,
S3 ViRGE,
Voodoo2,
Geforce4 Ti4200

So far, from what I've found out, it's only the -5v which renders the LA portion impotent. Previously, I was of the impression that the -5v has something to do with the ISA slot or the motherboard make which has some sort of -5v channel line supplying it in-situ. Thanks to swaaye, I came to know the problem was with the PSU not having the -5v line option, as depicted on the PSU's label.

retro games 100 wrote:

If an ISA card requires -5v, and the PSU that you use does not supply this type of voltage, what happens? Does the PC fail to boot? Or does the ISA card in question not function correctly?

What I have observed from this experience is that there is no problem in booting. Just the said component refused to work. No other problems were noted.

swaaye wrote:

My big 'ol Ensoniq Soundscape cards don't work without -5v.

Why might that be? None of the Ensoniq cards I've seen have a -5v finger...

Great Hierophant wrote:

If no other option exists, you can use a 7905 Voltage Converter to derive -5v from -12v.

Some cards do exactly this. Instead of using the bus rail, -5v is "generated" onboard (e.g., the entire PAS line).

Cloudschatze wrote:

Why might that be? None of the Ensoniq cards I've seen have a -5v finger... […]
Show full quote

swaaye wrote:

My big 'ol Ensoniq Soundscape cards don't work without -5v.

Why might that be? None of the Ensoniq cards I've seen have a -5v finger...

Great Hierophant wrote:

If no other option exists, you can use a 7905 Voltage Converter to derive -5v from -12v.

Some cards do exactly this. Instead of using the bus rail, -5v is "generated" onboard (e.g., the entire PAS line).

I remember testing a PAS card, with a mobo that was powered by an ATX psu with no -5v. The sound coming from the PAS card was extremely strange, because the sound was greatly speeded up. (Of course, this strange behaviour may be a coincidence, and have nothing to do with the psu.)

The psu was a well known, modern model called Corsair HX520. Good quality, although very much geared up towards using it with a modern mobo, because it catered very well for the 12v rails.

retro games 100 wrote:

(Of course, this strange behaviour may be a coincidence, and have nothing to do with the psu.)

The PAS cards lack -5v fingers, so whether a PSU provides -5v, or not, is irrelevant.

The problem might have been timing-related. If you ever get the chance, try adding "t:1" to the mvsound.sys parameters. This configures the card to use its onboard timer, rather than the host timer, and might fix the playback-speed issue.

I'm not sure if anyone cares, but a few other well-known cards that use the -5v rail are the Sound Blaster 2.0, and Sound Blaster AWE32 Upgrade Card.

Cloudschatze wrote:

The PAS cards lack -5v fingers, so whether a PSU provides -5v, or not, is irrelevant. […]
Show full quote

retro games 100 wrote:

(Of course, this strange behaviour may be a coincidence, and have nothing to do with the psu.)

The PAS cards lack -5v fingers, so whether a PSU provides -5v, or not, is irrelevant.

The problem might have been timing-related. If you ever get the chance, try adding "t:1" to the mvsound.sys parameters. This configures the card to use its onboard timer, rather than the host timer, and might fix the playback-speed issue.

I'm not sure if anyone cares, but a few other well-known cards that use the -5v rail are the Sound Blaster 2.0, and Sound Blaster AWE32 Upgrade Card.

I definitely remember trying that "t:1" parameter you suggested many months ago, here on Vogons...but no joy I'm afraid. One day, I will dig out the PAS card again, and retest it in a different mobo.

Regarding the Sound Blaster 2.0 you mentioned directly above, is that the CT1600 model? If so, I bought one the other day, and I would be interested in testing it out on my current mobo+psu combo, the psu of which is the Corsair HX520, the one that lacks the -5v rail. (At least, I believe it lacks this -5v rail, as there is no mention of this specific piece of information on the Corsair website.)

Thank you, best regards, Robert.

retro games 100 wrote:

Regarding the Sound Blaster 2.0 you mentioned directly above, is that the CT1600 model?

No, it's the CT-1350B.

The CT-1600 (SBPro2), ought to work just fine with your PSU.

It seems there will now be retro-PSUs 😀 The ATX spec dropped the -5V line in one of the latest revisions: ATX12V 2.1 (it wasn't required since ATX12V 1.2), so I probably buy some quality older PSUs before they vanish from the market.

GL1zdA wrote:

It seems there will now be retro-PSUs 😀 The ATX spec dropped the -5V line in one of the latest revisions: ATX 2.1 (it wasn't required sinse ATX 1.2), so I probably buy some older quality PSUs before they vanish from the market.

Bloody hell! 🤣 That's another item to add to the retro shopping basket! 😉

Great Hierophant wrote:

If no other option exists, you can use a 7905 Voltage Converter to derive -5v from -12v.

Please can you elaborate? What is a 7905 voltage converter? Is it something you can attach to a modern ATX 2.1 PSU?

Thanks a lot.

GL1zdA wrote:

so I probably buy some quality older PSUs before they vanish from the market.

Yep. That "vanish from the market" is a scary statement stuff, at least for us, nostalgia pursuers.
I better stock a couple too, at least, for the sake of my LAPC-I! 😁

GL1zdA wrote:

...so I probably buy some quality older PSUs before they vanish from the market.

Any recommendations please? 😀

Cloudschatze wrote:

Why might that be? None of the Ensoniq cards I've seen have a -5v finger..

No idea. The card just would not work until I put a PSU with -5v in. It refused to even initialize. Perhaps the motherboard needs -5v? It seemed fine though aside from the wacked out -5v reading in the BIOS and the ISA slots.

Malik wrote:

GL1zdA wrote:

so I probably buy some quality older PSUs before they vanish from the market.

Yep. That "vanish from the market" is a scary statement stuff, at least for us, nostalgia pursuers.
I better stock a couple too, at least, for the sake of my LAPC-I! 😁

I'm sure they'll be available second-hand for decades to come. And ATX would probably have to be thoroughly obsoleted for new -5v ATX PSUs to go away completely anyway.

I haven't tested the Roland LAPC-i internal soundcard, because I haven't got one, but the following hardware configuration seems to work -

ATX PSU (with no -5v rail) + ATX to AT power cable adaptor + 486 mobo + either SCC-1 or MPU-401AT

I tried running both Dark Forces (sound) setup utility, and also Roland's sound check utility (chkscc.exe), and both worked. I wonder if this test would work if I hooked up a Roland external module, such as a CM-32L? It should do, I reckon.

Is it just a small handful of old sound cards that require -5v rail on the PSU, or are there other old components which require it, such as graphics cards?