Yeah that is a very custom 15pin back panel part (remind me to never consider an Ipex case 🤣) . Have seen other cases with built in amp and speakers but the input is way more obvious and easier to adapt. One of my cases has amp+speakers but a true 1/8" stereo input jack on the back so you only need a short cable from sound card "line out" to the "amp in" connection., my other speakered case actually has a short 1' cable out the back with mini plug to directly plug into the sound card output.
Good luck !

canthearu wrote on 2021-08-07, 23:45:

Warlord wrote on 2021-08-07, 19:44:

this thread is confusing to go through.
Basically what you need is a multimeter that can do continuity. You can get a multimeter at almost any hardware store.

All you need to do is set the multimeter to continuity. Touch one probe to the speak left or right and, touch the other probe to the rear db15 connector pin and probe till it rings.. When you hear a ringing you have continuity and thats how you trace it. Once you figure out each pin, get a blank db 15 connector and a male to male 3.5 cable. Cut the cable and solder the wires to the plug. Its easy peasy.

Won't be that simple since there is likely an amplifier for the speakers.

But that side, I can probably sill work it out if nobody here is able to.

I'm pretty sure the amplifier is that TEA2025 chip U2, with input on pins 7 & 10. I don't know if that's before or after the volume control potentiometer VR1&2. It looks like the amp can be bypassed by moving JP6&7, which I guess puts a line level signal on the headphone socket. I'd probably start trying to work out the pinout between the DB15 and the 3x2 plug, mostly because it might be possible to arrange things so both the plug and DB15 can be seen at the same time. Then work out the connections from the 3x2 header, looking particularly for connections to U2 7&10.

I don't have any soldering or electronics equipment, let alone experience with this sort of thing. I'm sure that I could buy it all and spend the time to get it right, but that goes beyond what I was willing to do just to test out the internal speakers. Also, I feel like my curiosity about the whole thing has been sated now that I have a fine understanding of the situation thanks to you brilliant chaps in this thread!

I hope that this thread is useful to someone else, such as yourself canthearu. Be sure to post some pics here if you ever find an adapter or end up making your own!