NeXT RGB Board

Started by gtnicol, December 14, 2013, 03:20:29 am

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gtnicol

I believe this is a board NeXT used for connecting to projectors (I originally thought they were Extron boards, but apparently not). I've never actually put one of these in a cube, but I am thinking of trying it out this weekend. I can't think of what that cable would be connected to. Any ideas?


barcher174

I'm curious, what are those screws under the cable?

cubist

Quote from: "barcher174"I'm curious, what are those screws under the cable?

Heat sink for 78xx/79xx series voltage regulators.  The heat sink being a big piece of copper plane in these cases (most likely).

pentium

Ooh, I know that board *scans through Fall '90 catalogue*

It does actually list it as the Extron board from Extron Electronics (and if you want more info, you called Extron's Santa-Fe Springs office)

QuoteThe board accepts the 63khz horizontal, 68.3hz vertical high-resolution scan rate data directly from the internal vidoe data bus. Data timing are manipulated in memory to generate an interlaced video output at approximately 31khz horizontal and 34hz vertical. The result it the same apparent video resolution at a lower scan rate that's compatible with many multican type monitors and projectors.


Aside frrm half a page of text and a photo I have no additional details however it seems Extron did make another adapter which took your monitor connector and broke it to a monochrome composite output using RGB so I suspect the four BNC jacks are RGB and composite sync however this won't give you color.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

gtnicol

I thought it was an Extron too, but the logo on there says NeXT. The output appears to be RGB+S... I guess the theory of this is that you could have the board in a cube hooked up to a projector etc. while still being connected to either a soundbox and/or a display, and it would mirror the video on the display. It *seems* to be a pretty simple device, so it might be something people could replicate (be great if we could find the connectors for the bus... could make out own boards).

The screws are for a 7805C.

Quote from: "pentium"Ooh, I know that board *scans through Fall '90 catalogue*

It does actually list it as the Extron board from Extron Electronics (and if you want more info, you called Extron's Santa-Fe Springs office)

QuoteThe board accepts the 63khz horizontal, 68.3hz vertical high-resolution scan rate data directly from the internal vidoe data bus. Data timing are manipulated in memory to generate an interlaced video output at approximately 31khz horizontal and 34hz vertical. The result it the same apparent video resolution at a lower scan rate that's compatible with many multican type monitors and projectors.


Aside frrm half a page of text and a photo I have no additional details however it seems Extron did make another adapter which took your monitor connector and broke it to a monochrome composite output using RGB so I suspect the four BNC jacks are RGB and composite sync however this won't give you color.

gtnicol

Any thoughts on the cable? That one has me really curious.

jroark

There is no NBIC, I wonder if all those 7x ICs are the NBIC? Does the cable just plug into the MB or maybe a ND?

gtnicol

I think all the memory is used to buffer, and thereby change the scan rate. I initially thought that the cable might plug into the motherboard or dimension, but there's nowhere for it to connect to!

pentium

QuoteI thought it was an Extron too, but the logo on there says NeXT.

The photo I have has the NeXT logo on it too.

Edited: Oh, I know what the ribbon cable is for! Look in the lower right of an 040 board in the video section.


There's an unpopulated header with the correct number of pins and in reach of the tiny cable. It's an internal video header!  :shock:

Edited: Oh god, my mind is now swirling with ideas like an 040 in the painted black case of an iMac G5.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

gtnicol

Now that's interesting. I think I have a motherboard with that header broken out, so yes, that makes sense.

pentium

By off chance, is the header on the backside of your 040 board? There's no way the cable can reach the other side of the board.

Edited: Also, is there an extra component under the connector? There's a lone empty set of pads on the board I pictured.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

jroark

Cool, if it's just RGB/S a VGA expansion board could be possible.

I see a bunch of 74x ICs, 6x CA3054 DUAL OP-AMPs, and a couple AMD AM7201-25PC FIFOs

gtnicol, maybe a parts list and some closeups of the top and bottom?

Anyone good at tracing circuits?

gtnicol

I'll have to dig up the board, but yes, from memory it had a gray connector on the back of the board.

I'll try and get some better photos... my scanner doesn't quite handle the size of the NeXT boards.

Quote from: "pentium"By off chance, is the header on the backside of your 040 board? There's no way the cable can reach the other side of the board.

Edited: Also, is there an extra component under the connector? There's a lone empty set of pads on the board I pictured.

gtnicol


pentium

WOAH! The connector is on the 030 board too!
Yep, you got an extra Motorola chip. I can't make out the part number on it though. Might be important.

Edited: looking at my own 040 board it IS very important to that connector. At least 11 traces snake from the pads to the connector.

Let me take some high-res photos of this.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram