MediaVision Pro Audio Spectrum 16 - Breakout box pinout?

I recently bought a lot of LCs, which includes the MediaVision PAS16 sound card, in its LC PDS variation. The only problem is that the Macintosh versions of the PAS16, unlike the ISA PC version, does not have any audio jacks on the card itself. Instead, it has a DB-15 port that connects to a little breakout box, that provides various audio in and out jacks, as well as MIDI (and optionally a DB-15 Joystick port).

Counting the signals, I'm guessing it's not actually a very complicated device. Does anybody on the forums here happen to have the breakout board, and if so, be willing to open it up and see if we can work out the pinout of the DB-15 port on the card, as well as potentially a schematic for the box if it does have active components? This wouldn't just be helpful to me, but to others who might find one of these cards without the box as well. Any help is greatly appreciated!

EDIT: The port might actually be a three-row DB-26 connector, most pictures of these Mac cards online don't properly show the port. In that case, it adds to the theory that these breakout boxes are rather uncomplicated devices.

You probably found these pics already?

Yes, but I'm specifically looking for pictures of the PCB inside the Patch Panel, so we can work out what the pinout is and how to replicate it.

Quick search online shows the exterior of the port. I do have one of these for the Nubus series and I'd be happy to crack it open, but it's at my parents' house and I'm not sure when I'll be there next.

I have to of the these NuBus cards and one breakout box, but after probing it seems like there are screws behind the port label plastic sheet on the front which I don't want to ruin. Alternatively I have wondered about doing some multimeter testing to see if I could find the specific pins on the HBD-26 connector for Headphones and Mic in (which I'm most interested in using with my other card)

So I just tried to tone out the pins on the breakout box with no luck. Only found continuity between the grounds on all the ports (including the outer shroud of the HDB-26 connector. Makes me think there most be some electronics in the breakout box…

I guess think makes sense since there are more than 26 signals on the breakout ports (other than ground)

Joystick: 15
Midi In: 5
Midi Out: 5
Headphones: 2
Stereo Out: 2
Stereo In 1: 2
Stereo In 2: 2
Stereo In 3: 2
Stereo In 4: 2
Mic In: 1
…Totals 38

@Fizzbinn yeah I suspected toward that when I saw some of the descriptions on the back of the box. especially if I won't be surprised to find at least two audio mux's beside other chips inside the breakout on basis of the first feature underneath 'audio mixing'

MIDI and Joystick ports don't use all the pins, so that eliminates some. Did this card use an outbound ADC in the breakout for recording?

Got mine open and have documented the PCB for starting a schematic development thread. IOW, it's not a simple pinout development project you've got started here.

Three generic ICs may support Sound OUT and MIDI I/O schematic development for doing a limited function PCB. MEDIAVISION's THUNDER custom IC appears to be a condensation of logic and DAC supporting the five analog Sound INPUT channels at first glance.

I'll fire up a thread in hacks for anyone interested in taking this project farther along than visual mapping in AI, which I don't currently have time to do at present anyway.



DO NOT try to take one apart, it's a hot mess and needs to go back together with hot glue!

So you need the breakout box and its electronics to use the card.

Darn, that does complicate things. Still, if only MIDI and Sound Out could be implemented in a recreation, I'd still be very content as those would be the most important features to me personally. I'll see if I can help out in any way in the Hacks thread.

Unknown_K said:

So you need the breakout box and its electronics to use the card.

Click to expand...

Yes, unfortunately the only port on the NuBus card cannot be directly used. Would be great to be able create a simplified break out cable (or smaller box) with just stereo/headphone out and mic in.

@Trash80toHP_Mini Thanks for doing this!

You'll have to get someone involved who does traditional schematic development to get anywhere with that project. I just kicked it off, if you can link to or upload the Spec Sheets 0f the three generic ICs that would be a great leap forward.

I'm keeping my board out in order to buzz connections on traces that may be obscured on the component side. Interestingly, there are at least a couple of traces that go nowhere at all that appear to be the equivalent of alternate ground lines for preventing crosstalk digital signals, guessing they're shielding for analog transmission lines?

Interestingly, there is no RFI shielding for the case at all.

Unknown_K said:

So you need the breakout box and its electronics to use the card.

Click to expand...

Dunno, you may be able to rig the card up as a Game Port directly off the connector? Otherwise that'd be an unfortunate guess at a yes.

Fizzbinn said:

Would be great to be able create a simplified break out with just stereo/headphone out and mic in.

Click to expand...

Might not bee too difficult to simplify the five way input setup it to that single source? Dunno, but I suggest you move your wish list and possibility discussion to the hacks thread to keep the project alive and on a more practical footing.

Well, the LF247s are quad Opamp ICs, and the HP 6n136 appears to be MIDI related, so anyone with a decent knowledge of analog electronics could probably figure this out easily enough (disclaimer: that's not me!).

I don't know what that Thunder MVA611 does, though. My best guess is that it's also related to MIDI somehow?

c

The Spec Sheets for those ICs are linked in the PatchPanel thread.

Trash80toHP_Mini said:

The Spec Sheets for those ICs are linked in the PatchPanel thread.

Click to expand...

Huh, the link I see in your post from earlier today seems to recursively loop back onto itself?

Unless I'm looking at the wrong one, which is entirely possible!

c