Try swapping the PSU.

kolderman wrote on 2020-03-01, 05:42:

Try swapping the PSU.

Sorry, but I mentioned using two different PSUs in my post.

What you describe visually sounds like a DC offset problem on the outputs. If you have a multimeter you could measure if this is the case. There should not be any voltage measurable between ground (chassis) and the output of your sound card when there is no audio being played. Also, you could try measuring the voltages on your motherboard to check if they are correct on the ISA and PCI slots. You can lookup the pinout and probe them.

This certainly seems to be a DC offset thing. A lot of cards when jumpered for line out bypass all the components on the signal path, including DC blocking capacitors and there's always a DC offset at (close to) half power supply voltage of a typical sound chip.

Ozzuneoj wrote on 2020-03-01, 04:49:

I'm putting together a little Windows 98SE system to use as a very simple CD Player + MIDI player for my daughter. The system is […]
Show full quote

I'm putting together a little Windows 98SE system to use as a very simple CD Player + MIDI player for my daughter. The system is almost completely original (in a nifty micro atx case from the late 90s, with a handle on top and the original specs listed on a label on the bottom) and is running an ECS P6EX-ME 440EX board, a Deschutes PII 266, 128MB SDRAM, S3 Virge and a recent 350W Seasonic 80 Plus Bronze PSU for safety\longevity. I've revised this post 5 times as I've kept troubleshooting things, so forgive me if it is broken up.

The problem:
I have tried MANY sound cards in this motherboard and they all work but they exhibit the same very worrying feedback\noise when I adjust the volume on my mini-amp (or on a cheap set of Dell speakers). What I mean is, I can hear a soft chuffing\scratching sound and I can see the speaker slowly moving in and out as I turn the volume control on my amp\speakers. Playback is fine, but I get this really unhealthy feedback every time when I adjust volume. I have seen and heard this before when connecting a speaker\amplifier to a mic or line-in jack by mistake, but I've never seen this happen on a line-out.

Not all cards have this issue, but many do. There is nothing else changing, no CD\AUX inputs connected, nothing connected to the mic or line in jacks, and I can literally take out one card, put in another and immediately I get the feedback once the system is powered on, long before any drivers have been loaded. The noise will keep happening as I adjust the volume a few seconds after the power has been turned off and then it will fade out, presumably when the power supply or other capacitors have discharged. Also, I just tried taking the motherboard out of the case entirely and it still does it with only the board, and a power supply (tried an old early 2000s Antec PSU too). Even with no RAM and CPU there is still a slight movement from the speaker when adjusting volume. For some reason the movement is much more pronounced when a CPU is added, but I tried a different CPU as well and it made no difference.

Cards I have tried that have the problem:
Onboard ESS ES1869 (whether it is jumpered to be enabled or disabled it does it)
FOUR (yes four) Labway A301-G50 YMF-724 PCI cards
ESS SOLO-1 PCI
YMF-719E ISA
DCS YMF-724 card (similar to Labway but different layout) had strange thumping\scratching sounds when adjusting the volume, slightly different than the others.
Gallant SC-3000 8bit ISA card gave really odd AM\FM radio sounding noise from the speakers that would change when I adjusted the volume on my amp.

Cards that do not have any noise at all:
Generic YMF 724 (PT-2626... possibly Pine Technologies)
Vortex 2 AU8830 (the green triangular one)
IBM Mwave ISA
Sound Blaster CT2940 ISA

I have also tried switching the jumpers on the cards that have them from SPEAKER to LINE-OUT, but it still does it.

Since some cards have absolutely ZERO noise in this same exact setup, while others are incredibly bad, I'm not thinking that this is a filtering issue with the cards. If I had to guess, I'd say that the reason some cards do it and some don't is likely down to which PCI\ISA pins are connector or not connected. The super generic YMF-724 has all of the contacts on the PCI card edge, and the Vortex card has several that the other PCI cards don't have, same with the ISA cards.

Any ideas? Bad caps on the motherboard are one possibility since they look pretty generic, but this is a pre-plague board, and I haven't seen anything like this on any board before, no matter the age. I have owned this system for about 20 years and it has been well taken care of, though I haven't used it much in the last 15 years, so I can't say for sure when this started.

Hey,
Unfortunately I don't have any info that would be helpful to you, but I'm hoping you can help me out. I have a Gallant sc3000 that I've been trying to get to work in a Compaq Presario 5686 (PIII, 512mb ram, 1 ISA slot) without any luck. I have installation software for it, but when trying to install I get various error messages. I've tried in dos, win 3.1, and 98. Can you give me a quick rundown of how you were able to get it working?

Ahow77 wrote on 2020-11-10, 02:24:

Ozzuneoj wrote on 2020-03-01, 04:49:

I'm putting together a little Windows 98SE system to use as a very simple CD Player + MIDI player for my daughter. The system is […]
Show full quote

I'm putting together a little Windows 98SE system to use as a very simple CD Player + MIDI player for my daughter. The system is almost completely original (in a nifty micro atx case from the late 90s, with a handle on top and the original specs listed on a label on the bottom) and is running an ECS P6EX-ME 440EX board, a Deschutes PII 266, 128MB SDRAM, S3 Virge and a recent 350W Seasonic 80 Plus Bronze PSU for safety\longevity. I've revised this post 5 times as I've kept troubleshooting things, so forgive me if it is broken up.

The problem:
I have tried MANY sound cards in this motherboard and they all work but they exhibit the same very worrying feedback\noise when I adjust the volume on my mini-amp (or on a cheap set of Dell speakers). What I mean is, I can hear a soft chuffing\scratching sound and I can see the speaker slowly moving in and out as I turn the volume control on my amp\speakers. Playback is fine, but I get this really unhealthy feedback every time when I adjust volume. I have seen and heard this before when connecting a speaker\amplifier to a mic or line-in jack by mistake, but I've never seen this happen on a line-out.

Not all cards have this issue, but many do. There is nothing else changing, no CD\AUX inputs connected, nothing connected to the mic or line in jacks, and I can literally take out one card, put in another and immediately I get the feedback once the system is powered on, long before any drivers have been loaded. The noise will keep happening as I adjust the volume a few seconds after the power has been turned off and then it will fade out, presumably when the power supply or other capacitors have discharged. Also, I just tried taking the motherboard out of the case entirely and it still does it with only the board, and a power supply (tried an old early 2000s Antec PSU too). Even with no RAM and CPU there is still a slight movement from the speaker when adjusting volume. For some reason the movement is much more pronounced when a CPU is added, but I tried a different CPU as well and it made no difference.

Cards I have tried that have the problem:
Onboard ESS ES1869 (whether it is jumpered to be enabled or disabled it does it)
FOUR (yes four) Labway A301-G50 YMF-724 PCI cards
ESS SOLO-1 PCI
YMF-719E ISA
DCS YMF-724 card (similar to Labway but different layout) had strange thumping\scratching sounds when adjusting the volume, slightly different than the others.
Gallant SC-3000 8bit ISA card gave really odd AM\FM radio sounding noise from the speakers that would change when I adjusted the volume on my amp.

Cards that do not have any noise at all:
Generic YMF 724 (PT-2626... possibly Pine Technologies)
Vortex 2 AU8830 (the green triangular one)
IBM Mwave ISA
Sound Blaster CT2940 ISA

I have also tried switching the jumpers on the cards that have them from SPEAKER to LINE-OUT, but it still does it.

Since some cards have absolutely ZERO noise in this same exact setup, while others are incredibly bad, I'm not thinking that this is a filtering issue with the cards. If I had to guess, I'd say that the reason some cards do it and some don't is likely down to which PCI\ISA pins are connector or not connected. The super generic YMF-724 has all of the contacts on the PCI card edge, and the Vortex card has several that the other PCI cards don't have, same with the ISA cards.

Any ideas? Bad caps on the motherboard are one possibility since they look pretty generic, but this is a pre-plague board, and I haven't seen anything like this on any board before, no matter the age. I have owned this system for about 20 years and it has been well taken care of, though I haven't used it much in the last 15 years, so I can't say for sure when this started.

Hey,
Unfortunately I don't have any info that would be helpful to you, but I'm hoping you can help me out. I have a Gallant sc3000 that I've been trying to get to work in a Compaq Presario 5686 (PIII, 512mb ram, 1 ISA slot) without any luck. I have installation software for it, but when trying to install I get various error messages. I've tried in dos, win 3.1, and 98. Can you give me a quick rundown of how you were able to get it working?

Sorry for the late reply. I haven't been on Vogons much lately.

I don't remember what exactly I did, because I was only using it to test the system in the original post (never figured it out by the way... something wrong with the motherboard, but I'm not sure what).

Most likely I just used the add hardware wizard in the control panel in 98se and had it scan for non-PNP devices. I believe the SC3000 is basically just a Sound Blaster 2.0 clone, so it may not even need to detect it as a Gallant SC3000... it may just find a Sound Blaster compatible. Keep in mind, this is a mono card, so you're going to be missing out on stereo effects in most games from the early 90s on.

If you're dealing with any non PNP sound card in Windows 98, I'd recommend trying the add hardware wizard non-PNP scan first. I've had cards that refused to install, no matter what drivers I ran or what I tried to do with device manager... but letting the wizard scan for it, it popped right up, installed the generic drivers (which are probably the latest, since 98SE is so much newer than any non-PNP card) and worked fine.