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Pro Audio Spectrum 16 PatchPanel - Schematic Development for Reproduction

Trash80toHP_Mini

NIGHT STALKER
@Daniël started a thread inquiring about the pinout of the PAS16 breakout box, turns out to be a reproduction project.


DO NOT try to take one apart, it's a hot mess and needs to go back together with hot glue!
 
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Trash80toHP_Mini

NIGHT STALKER
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 possibly DAC supporting the five analog Sound INPUT channels at first glance:

PAS16-Patch_Panel-00.JPG

PAS16-Patch_Panel-01.JPG

It's a very pretty translucent two sided board which makes things a lot easier I think.


PAS16-Patch_Panel-03.JPG
PAS16-Patch_Panel-02.JPG

PAS16-Patch_Panel-05.JPG

PAS16-Patch_Panel-04.JPG

Don't try this at home, screw head is underneath the pretty logo sticker on the back.

PAS16-Patch_Panel-06.JPG
 

paws

Well-known member
Can the computer tell if the box is connected or not?

I'd put a scope on it to see what the computer is sending to the box. The MIDI lines, for instance, are bound to be more or less straight through and easily identified.

As for the audio, one technique that was common in musical instruments at the time was using a single DAC and sample and hold buffers. You'd see this even in high-end synths in the late 80's. In that context I've also never seen anything but off the shelf DACs. I'd be kind of surprised if there were five 16-bit DACs in that custom IC. Do we have a good shot of the Nubus board?
 

Trash80toHP_Mini

NIGHT STALKER
I'll post a higher res sectional set later. Mine also came sans PatchPanel, so I got the LC version NIB during the fabled Shreve clearance just for the panel. I'll post pics of that board as well.
 

paws

Well-known member
I'm counting 5 quad op amps (LF347) in the half of the board closest to the output, so I strongly doubt it's sending all-digital signals to the Patch Panel. There's also the Yamaha YMF chip, which is a synth IC, and it's companion DAC, the YAC512, so there is definitely something analogue happening on this end. Definitely put a scope on it if you have one.
 

Fizzbinn

Well-known member
I'm counting 5 quad op amps (LF347) in the half of the board closest to the output, so I strongly doubt it's sending all-digital signals to the Patch Panel. There's also the Yamaha YMF chip, which is a synth IC, and it's companion DAC, the YAC512, so there is definitely something analogue happening on this end. Definitely put a scope on it if you have one.
I don’t have a scope but I did attempt to find continuity between the the stereo out and headphone ports on the patch panel and its 26 pin connector and couldn’t find any.
 

paws

Well-known member
Have you tried following the traces backwards from the jacks? It'll go through at least some passives, maybe the opamps. Either it goes through the custom IC or directly to the port.
 

Trash80toHP_Mini

NIGHT STALKER

PatchPanel PCB Components:

LF347M Datasheet

There are a pair of LF147/LF347 Wide Bandwidth Quad JFET Input Operational Amplifiers. One OpAmp per eight RCA input channels?

6N136 Datasheet

One Optocoupler? DAMNFINO?

THUNDER custom IC, presumably gate control for selection of five audio inputs from PatchPanel jacks to PAS16 Card? Three control bits on interface cable?
 
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Trash80toHP_Mini

NIGHT STALKER
Good, then I'll try to make some time to determine the OpAmps' function. WAG from the general layout of the board would be that they probably aren't needed for the Audio Output/MIDI section. They're location suggests to me that they were positioned in a handy spot for running traces to the input section through the mere six traces required for the RCA and Speaker Jack components.
 

Trash80toHP_Mini

NIGHT STALKER
Finally got the copy stand set up and noodled out method to keep component and solder sides in the same plane of focus along with backlighting. I'm loving the rugger's hand me up Canon DigiCam with articulated LCD display for easy copy work!

PAS16-PCBdev-000.JPG

Now to get AI9 up and running on both displays for the QS'02 finally, first time post flood. :rolleyes:

1) eliminate game port
2) eliminate traces heading past RCA/Headphone stereo out jacks and MIDI I/O connectors to inputs dependent upon the THUNDER IC
3) develop "visual schematic" mapping in AI
4) find a volunteer to translate my trace mapping into prototype stubby PCB with the analog inputs lopped off 😬
 

Trash80toHP_Mini

NIGHT STALKER
Thanks much max, I'm hoping that's the only active component required for the abridged Stereo Outputs/MIDI I/O only version for folks who've got cards, w/o PatchPanel. I'm looking more seriously at this as I have NuBus and LC version, but only one box.
 

Trash80toHP_Mini

NIGHT STALKER
Great info there on the ICs. What struck me most would be that 16bit ISA Cards seem to be a sorry lot as opposed to the 32bit Mac Card/PatchPanel setup.

The most I've seen so far would be a backplane plate with maybe three(?) analog stereo input jacks, with one jack out and a Game Port? Makes sense if it was only aimed at competing with SoundBlaster and not aimed at serious level sound production? No MIDI I/O on the PC version? Was there a PatchPanel at all in the PC realm? I've yet to find either.

Sounds like THUNDER on the ISA Card versions take care of mixing two inputs for output? Thunder is not present on NuBus or LC versions of the interface card. The THUNDER ASIC(?) is on the PatchPanel way out on the far end of the card next to all five analog stereo input channels. curiouser and curiouser.

Gotta read that stuff closely if I ever wind up taking a shot at figuring out the analog input side. Isolating it from the sawed off version will be as far as I'll go at this point.
 

Trash80toHP_Mini

NIGHT STALKER
Looks like Sound Blaster implemented MIDI on unused pins 8 for MIDI out and 14 for MIDI in on its Game Port connector. What I was thinking was a third analog input jack on one version of the card would actually be a MIDI jack.

Really interesting stuff in this one:
Sound Blaster Series Hardware Programming Guide

Interesting tidbit: THUNDER might have its namesake in Media Vision's bog simple, 8bit ISA Sound Blaster compatible Thunder Board.

In none of the Media Vision or PAS16 research I've seen so far have the Macintosh products been mentioned?
 
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