Hello NeXT Community: I'm looking to buy or trade for NeXT Non adb soundboxes or soundboards out of 4000a monitors. I am willing to buy them but would prefer trading I have lots of nice NeXT stuff new old stock ! Best regards Rob Blessin
I may have the ASIC schematics for these boards... it'd be great to come up wit a good, cost alternative to these things...
Quote from: "gtnicol"I may have the ASIC schematics for these boards... it'd be great to come up wit a good, cost alternative to these things...
Hello Gavin: Great that will help! I have a couple of guys that are going to see if they can get the ADB soundboards to talk non adb , I started a thread under worklogs. As I have a surplus of ADB cards the thought is we can hopefully modify them to become non adb compliant , if it works we can resurect a lot of the earlier NeXTs using the ADB to Non ADB soundboards , a custom cable and a flat panel ..... now if only we can figure out a way to get the model 152 power supplies to work with flatpanels as well!
From looking at the boards, I think the primary difference is really the ASIC and the connectors. At the end of the day, the boards are really just multiplexing and splitting signals onto the bus, so someone with good hardware skills should be able to design a simple replacement.
That said, I have a raspberry pi just waiting on on the side for this... voltage level conversion is probably the main issue.
I share the belief that the best way to handle this is to come up with a complete replacement. I just purchased some level converters a couple weeks ago with the intent to look into driving this using a Pi. The problem is the 20mhz frequency of the bus. I think we will be stressing what the GPIO can handle.
Also the power supply should not be too difficult. There must be a sense amp somewhere on the 12V rail.
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Brian
Never mind, definitely not a sense amp for the power supply. I have a board out and will try to look into this.
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Brian
I also agree a full replacement is a better approach. Here are a few relevant links -
http://68k.org/~degs/http://www.mind-to-mind.com/blog/2011/11-10-2011.htmlhttp://www.mind-to-mind.com/blog/2012/02-12-2012.htmlGiven the comments in the last link I think the best approach is an FPGA. I doubt that a Linux based system like the RPi will be able to satisfy the "hard" timing requirements. An Arduino is probably not fast enough to read and write the input and output buses both running at 20 MHz.
BTW the opencores project have an I2S module in VHDL -
http://opencores.org/project,i2s_interface,overviewPersonally I'd integrate a VGA adapter into a sound box replacement - put in a sync separator for colour systems to solve the SOG problem and/or properly split the greyscale signal to the RGB pins for B/W systems.
Also just have stereo jacks for mic and speakers. Lots of VGA monitors have build in speakers.
This -
http://www.ebay.co.uk/itm/A2split-for-Apple-II-IIe-IIc-IIc-IIgs-Floppy-Disk-3-5-5-25-adapter-splitter-/161281159847could be useful for examining the monitor bus signals. The seller also has a number of different DB-19 connectors.
I'll see if I can dig out the ASIC design... it's the thing that handles multiplexing . All the other chips are relatively standard from what I can see.
If you have the ASIC design that would be insanely helpful.
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Brian Archer
I'm pretty sure I do. FWIW. The bus on the cable is 5Mhz, not 20Mhz, so I'm pretty sure a pi can handle that. It's a waste though...
Power supply modification directly might be a non-starter. I think it would require significant rework. There are alternatives however. Each nextbus slot is afforded ~25W of power from the supply. From my tests it appears that we need a minimum of 5 - 6W of power draw to keep the supply turned on. If we have less than that we risk damaging the supply even if we can override the protection circuitry. This would be a very bad idea. So that leaves us needing a way to burn off 5 -6W with a constant load. Using power resistors is one option. I made a circuit using 4 25W 20ohm resistors (2 in series and both legs in parallel for a total of ~20ohm resistance). This will work, but generates a significant amount of heat. We would not want this inside the cube. Generally speaking if you want to burn power you need to convert it to either heat or work ( movement, light, radio, etc). So I propose 2 solutions. The first is to use a 12v fan which consumes > .45A. I did not have one on hand but I did have 2 fans which added together accomplished this. This worked well, but of course there is a noise component. On the other hand, it's hard to fault having additional cooling inside the cube. I have a 90mm fan on order which is rated for .5A so let's see how that does. We will have to find old stock as almost none of the newer fans will use that amount of power. The second solution is to just connect a 12V, 6W lightbulb. These could probably be found at any auto parts store. The down side to this is the annoyance of bright light shining from the cube and we would still likely need a fan to blow out the heat. For either of these solutions we would be sacrificing one of the nextbus connectors to draw power from. I envision just a plugin card with a fan connector / bulb slot which could easily be installed or removed.
Thoughts?
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Brian Archer
I think the later power supplies don't need the draw to stay on.... I'd have to verify though.
Ok here is what I had in mind:
https://www.dropbox.com/s/32u54u22pzultrv/IMG_0483.jpghttps://www.dropbox.com/s/p6u0mbzeewtjnma/IMG_0482.JPGhttps://www.dropbox.com/s/jnwxhx8979yo3zr/IMG_0481.jpgThis is the simplest solution to the problem. The cable could also be modified to accept a bulb. This example is a 10W halogen I found at a target for $4. A lower wattage bulb could be found to minimize the brightness. Use the -12V power.
Here is the nextbus pinout:
https://www.dropbox.com/s/qm650a2wf55wzvf/screenshot_15.pngThis can be hacked together for <$20, and requires no permanent modification.
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Brian
Nice!
I hope this doesn't lead to wanting to put a window in the side of the case and have multi colored twirling neon fans, etc.
:)
Quote from: "barcher174"Ok here is what I had in mind:
https://www.dropbox.com/s/32u54u22pzultrv/IMG_0483.jpg
https://www.dropbox.com/s/p6u0mbzeewtjnma/IMG_0482.JPG
https://www.dropbox.com/s/jnwxhx8979yo3zr/IMG_0481.jpg
This is the simplest solution to the problem. The cable could also be modified to accept a bulb. This example is a 10W halogen I found at a target for $4. A lower wattage bulb could be found to minimize the brightness. Use the -12V power.
Here is the nextbus pinout:
https://www.dropbox.com/s/qm650a2wf55wzvf/screenshot_15.png
This can be hacked together for <$20, and requires no permanent modification.
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Brian
Instead of a light how about a wireless wifi card!
It will be difficult to find one that uses > 5W, but really you can use a combination of whatever to satisfy the requirement. Maybe a wifi router and small fan. Maybe I'll print a board that has -12, 12, and 5V broken out so that it's easy to add whatever to satisfy the requirement.
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Brian
I got a .45A, 12V fan, and by powering it from the -12V supply, everything is working as expected. Alternatively I tried a 5W bulb and the brightness is much more manageable. I think the bulb is a good option if you don't have a dimension installed because there is no noise component.
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Brian
