Beware - I have one of these and found the same problem as the original poster in this thread: IBM PS/1000 486DLC2-66 that it can not make PCM audio. It can do FM, but no wave sound. I forgot to update the post, but I've got one here:
What IBM 486 computer could this motherboard be from?. Mine appears to have been in an LPX case, though I've never found what computer it could have been in that would have 3 horizontal expansion slots.

I found out this is likely to be fault of the motherboard design, though I've no idea how to fix it. Here are the results of my poking around for related newsgroup posts:

https://groups.google.com/forum/#!search/time … FE/0MIncB-LoKIJ
"In addition the original advert also said:
Enhanced 486-66 processor with 16K internal cache and 256K external
cache (Blue Lightning).
Upgradeable to Pentium technology.
Massive 8MB RAM expandable to 64MB on the motherboard.
State of the art 32-bit VESA local bus windows accelerator with 1MB
video RAM (upgradeable to 2MB)."
"The blue lightning board otherwise known as a cobalt mb and produced
for ibm by alaris is a piece of absolute...

Sound may be broken with 32-bit applications? Another post about it:
https://groups.google.com/forum/#!search/486b … SA/yGOyXOFYEM4J

"Time PC (IBM/Colossus 486/66 BL2)"
Jolyon Smith: https://groups.google.com/forum/#!topic/comp. … xF3tc%5B1-25%5D
"I bought a Time PC (IBM/Colossus 486/66 BL2) over 2 years ago. No
hardware problems
,apart from a motherboard bug which only affects digital sound in some
games

A thread that appears to be discussing this particular board: https://groups.google.com/forum/#!topic/misc. … rds/sihnBVqPqh8

Some specific configurations may be able to coax sound out of it, I haven't tried though: https://groups.google.com/forum/#!search/486b … P8/1h-gzJDiwYoJ

Thermalwrong wrote on 2020-03-05, 22:00:

Beware - I have one of these and found the same problem as the original poster in that it can not make PCM audio. It can do FM, […]
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Beware - I have one of these and found the same problem as the original poster in that it can not make PCM audio. It can do FM, but no wave sound. I forgot to update the post, but I've got one here:
What IBM 486 computer could this motherboard be from?. Mine appears to have been in an LPX case, though I've never found what computer it could have been in that would have 3 horizontal expansion slots.

I found out this is likely to be fault of the motherboard design, though I've no idea how to fix it. Here are the results of my poking around for related newsgroup posts:

https://groups.google.com/forum/#!search/time … FE/0MIncB-LoKIJ
"In addition the original advert also said:
Enhanced 486-66 processor with 16K internal cache and 256K external
cache (Blue Lightning).
Upgradeable to Pentium technology.
Massive 8MB RAM expandable to 64MB on the motherboard.
State of the art 32-bit VESA local bus windows accelerator with 1MB
video RAM (upgradeable to 2MB)."
"The blue lightning board otherwise known as a cobalt mb and produced
for ibm by alaris is a piece of absolute...

Sound may be broken with 32-bit applications? Another post about it:
https://groups.google.com/forum/#!search/486b … SA/yGOyXOFYEM4J

"Time PC (IBM/Colossus 486/66 BL2)"
Jolyon Smith: https://groups.google.com/forum/#!topic/comp. … xF3tc%5B1-25%5D
"I bought a Time PC (IBM/Colossus 486/66 BL2) over 2 years ago. No
hardware problems
,apart from a motherboard bug which only affects digital sound in some
games

A thread that appears to be discussing this particular board: https://groups.google.com/forum/#!topic/misc. … rds/sihnBVqPqh8

Some specific configurations may be able to coax sound out of it, I haven't tried though: https://groups.google.com/forum/#!search/486b … P8/1h-gzJDiwYoJ

I assume you wouldn't want to sell it?

Split necropost to new thread.