BitWrangler wrote on 2021-12-04, 13:54:
On a desktop board speaker would be a 2 pin INPUT to play the PC onboard speaker through the soundcards filter and amp and out through headphone or line out.
I know. I've wired up a few crazy things in my time on my vintage PC's to do things like direct all audio through the internal speaker or direct audio through other things. It's a bit of an extention of my guitar building/pedal building capabilities. How I think the speaker pin works is that audio goes to ground (as usual) on the "-" side, and the "+" side goes to the speaker. Almost all audio, for guitars at least, are wired in this way.
Actually making some headway on this this morning from the connector.....not much but I did figure this out using an external speaker...
I started by finding out the grounds of the card using a VOM - I found actually, when the card is inserted into the computer, the card becomes a part of the computer's ground plane, at least the ring around the connector does, and the casing of the PCMCIA card itself (if conductive). Basically, put one connector on the metal bracket on the back outside of the Versa (which goes to the motherboard's main ground/- side), and then put the positive onto the case on the continunity setting and got full continuity from the backplane to the card.
So I setup an alligator clip to the M/75's rear backplane, carefully wired up a test harness to a 4ohm internal speaker I had laying around, and I think I got some audio signal off the pins, but it looks like the card uses a different method. The KMI KXL-C101 has a 34-pin header on the back with the pins all on the bottom of the connector - makes this relatively easy actually.
When I posted on this earlier, someone gave me a link to gut-shots of the card on this forum. I was somewhat able to trace signals from the ES1688S to the pins on the back, the first half of the pins (facing back of card, label up up, left to right) are audio pins based on where they are going, they go through a via, to a series of SMD components, then through another via somewhere, and following a lot of those traces often lead at least toward the ESS chip for the left side of the connector. It looks like (theoretical) Pin 1 goes to ground based on the solder pad it's attached to. Also, when I looked at pin 62 on the I/O header to the PCMCIA bus, there was just a bare pad, no via, no trace, so that pin is not even used.
I know, from building my own audio stuff, and a blurry picture of the breakout box, assuming the breakout box is not doing some of the work...
- There should be roughly about 3-5 audio signals coming off the card - 2 for the left/right output channels (+), one for Line-In/Mic in, or maybe those are separate.
- If the audio is using a separate ground plane, it could be 2 pins per each I/O, one for -, one for +, that makes things a bit harder
Anyway, fired up Versa, booted up Windows 95, opened up "shop.mid" in Media Player....went to town finding signals
Pin 1 = Ground
Pin 2 = unknown - maybe 2nd ground or no sound?
Pin 3 = Sound? - Small tic when connected to - maybe mic/line in?
Pin 4 = Sound? - Small tic when connected to - maybe mic/line in?
pin 5 = Squealing noise - possible + or - audio out?, got louder when touched with speaker + wire
Pin 6 = Squealing noise - possible + or - audio out?, got louder when touched with speaker + wire
pin 7 = Squealing noise - possible + or - audio out?, got louder when touched with speaker + wire
Pin 8 = Squealing noise - possible + or - audio out?, got louder when touched with speaker + wire
Going off of this, it seems one of two things apply.....or both...
1.) The "+" and "-" for the audio signals are all hosted off the card-edge connector on the back, so would need to build my own breakout connector to figure it out
2.) I think I MAY have heard some faint sound coming through the card-edge on some pins on louder sound pins (1/2 signal), which may suggest this
3.) If the sound comes out of the quieter pins, it could be the breakout box uses +5VDC? off the PCMCIA card to drive an amplifier
4.) Worst case scenario, I'm getting raw DIGITAL data and the audio has to hit an AD/DA converter in the breakout box (then it's time to find a box then I guess, or sell the card)
Either way, neat little experiment. I think to figure out what data signals come off the card, if not needing AD/DA would mean I can find that kind of card-edge connector or something I can modify to fit (right pin spacing, I really need a micrometer) and then wire up the first eight wires to it and see if I can pull full audio signals off. either way, I'm just glad I got the card setup and detecting. I really should ad the drivers to the Driver Library that I got.
BTW, to get the card working in DOS wihtout card services, it requires ASPIS365.SYS from Disk 1 of the driver disks with the following entries, I used DEVLOAD in FreeDOS to get that one up...but should work in CONFIG.SYS.
DEVICE=C:\XXXXXXXX\ASPIS365.SYS /PORT=240 /ADLIB /INT=5
If you have EMM386.EXE loaded you also have to (as with most PCMCIA cards) exclude the memory address of the card, in this case CE00-CFFF and /MEM=XXXX to set the memory address. CE00 is the default, but you can also re-assign to a different address using EMM386 and the /MEM= variable when loading the driver.
Anyway, even if It comes to nothing for me, at least this info is out there for someone to pick up where I left off if they feel like.