Trouble with Sound Driver on LC/LCII

Scott

New Tinkerer
Sep 30, 2021
37
24
8
I have some LC and LCII boards that were recapped over a decade ago by someone who no longer does re-caps that share a similar problem.

On the surface, these computers work fine. They run well, they chime upon startup, they do everything you'd expect them to.

The problem is that they have an issue with old sound driver playback. Not sound manager (the snd resource), but the old songs that were common in some games. These are the ones that won't play on a Power Mac.

Specifically, they have issues with Super Solvers Midnight Rescue and Super Solvers OutNumbered, where the sound is very low, seems to be only one channel, and is not audible.

These two games actually are of note because they play a different soundtrack depending on whether the computer is a mono or stereo output. If I load either on, say, my SE/30, you'll get Midnight Rescue playing "The Sorcerer's Apprentice" in stereo beginning on a concert A. It will be more simple on something like an LC, SE, or Plus and will start on a concert D.

Every LC and LC II *should* play the mono version regardless of whether it runs System 6 or System 7. (An LC III always would play the stereo version). It seems these LCs try to play the stereo version and fail miserably.

I'm wondering where the problem here lies, and I have it down to a few possibilities (all of which could be wrong, hence why I want to run it out here):

1. Some capacitor that governs the sound chip was replaced with an improper capacitor. (Back when these boards were re-capped, some people would use different caps to try to optimize the computer long-term, which didn't always work).

2. There's some kind of goop that wasn't cleaned up that landed near where something important for the sound chip is.

3. There's a software issue (although all of my Macs share a common deployment of System 6.0.8 and the other LCs with this work just fine).

4. Something else??
 

VeryVon

New Tinkerer
Jul 2, 2024
3
3
3
What happens if you try the 1/8 audio jack with an external speaker? Same issue? I believe both the LC & LCII have 8-bit mono sound output.