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Commodore 128 Video DAC Board Available

All,

Sorry for the delay, I had a minor health problem that pushed me back a week.

So, I built the first prototype, and it turns out that there are 2 bad connections to the ground plane. I'll be talking to the PCB vendor to try to figure out what went wrong, tomorrow.

With the 2 fixups in place, though, the board works fine.

Thanks!
- Alex
 
All,

I just ordered what will hopefully be the last round of prototypes. I moved some traces to prevent the ground plane disconnection that affected my first run.

Here are what will, hopefully, be the final boards.

Top:
top-v2.jpg

Bottom:
bottom-v2.jpg

I'll post another update when I successfully build this test board.

Thanks!
- Alex
 
All,

I have completed the building of the test board, and it tests successfully!

I will post an update, tomorrow, with details on how I'm going to go about selling these.

Thanks for everyone's patience!
- Alex
 
Alex,

Looks great. The only thing I see missing is a parts list. I've got some things to order for Mouser and Jameco, I could add these parts in...though it is probably just as easy and cheap to buy the whole kit from you!

Also, do you have any notes for how to connect the adapter to the GBS-8220? I see a header on it, but not sure what I would need to connect it...unless the 8220 has those type connections on the other end of the included cables? An ebay auction I found has photos of the cables, but they appear to be bare on the other end...

You note this works for PC CGA connections...does it just use a straight-through DB9 cable, or something special?

Thanks!!

Wesley
 
Wesley,

Yeah, all of that info was on the original thread, on Commodore128.org, which seems to have gone missing, recently.

The parts list is as follows:

Code: 
Qty  	Reference	Part Number		Description
======= =============== ======================  ================================
1	R13		309XBK-ND		RES 309 OHM 1/4W 1% METAL FILM
1	R14		324XBK-ND		RES 324 OHM 1/4W 1% METAL FILM
1	R15		365XBK-ND		RES 365 OHM 1/4W 1% METAL FILM
2	R4,R5		4.64KXBK-ND		RES 4.64K OHM 1/4W 1% METAL FILM
1	R6		4.32KXBK-ND		RES 4.32K OHM 1/4W 1% METAL FILM
1	R19		13.0KXBK-ND		RES 13.0K OHM 1/4W 1% METAL FILM
3	R10,R11,R12	10.0KXBK-ND		RES 10.0K OHM 1/4W 1% METAL FILM
3	R7,R8,R9	15.0KXBK-ND		RES 15.0K OHM 1/4W 1% METAL FILM
4	R3,R16,R17,R18	75QBK-ND		RES 75 OHM 1/4W 5% CARBON FILM
1	R1		2.2KQBK-ND		RES 2.2K OHM 1/4W 5% CARBON FILM
1	R2		3.3KQBK-ND		RES 3.3K OHM 1/4W 5% CARBON FILM
4	C2,C3,C4,C5	478-3193-ND		CAP CER 0.1UF 50V 20% RADIAL
1	C1		493-1144-ND		CAP ALUM 10UF 100V 20% RADIAL
1	IC2		296-3577-5-ND		IC TRIPLE 3-IN NOR GATE 14-DIP
1	IC1		TC74ACT244PF-ND		IC BUFF/DVR TRI-ST DUAL 20DIP
1	IC3		296-4348-5-ND		IC QUAD 2IN POS-NAND GATE 14-DIP
1	X1		621-009-260-042-ND	CONN DSUB PLUG 9POS R/A GOLD
1	IC4		AD8044ANZ-ND		IC OPAMP VF R-R QUAD LP 14DIP
1	POWER		A1921-ND		CONN HEADER VERT 2POS .100 TIN
1	H2		A1923-ND		CONN HEADER VERT 6POS .100 TIN

There is a 6-pin pigtail that comes with the GBS-8220 board, that you can solder to the board, where you see that I attached headers. From left to right, those connections are:

Ground, horizontal sync, vertical sync, red, green, blue

The power connector (the 2-pin header) is, from left to right:

+5 VDC, ground

You will need to solder the supplied (with the GBS-8220) 2-pin pigtail to these 2 pins.

Those are DigiKey part numbers. Note that a number of the resistors are precision parts, and this is important for color fidelity.

As far as CGA goes, a regular straight-through CGA cable works fine.

For anyone else who orders, please note that I have parts on order, and shipping will happen as soon as I get parts in, and assemble boards.

Thanks!
- Alex
 
Last edited:
ajacocks said:
There is a 6-pin pigtail that comes with the GBS-8220 board, that you can solder to the board, where you see that I attached headers. From left to right, those connections are:

Ground, horizontal sync, vertical sync, red, green, blue

The power connector (the 2-pin header) is, from left to right:

+5 VDC, ground

You will need to solder the supplied (with the GBS-8220) 2-pin pigtail to these 2 pins.
Click to expand...

Left to right with which end up? :)

So the 8220 provides 5v power to this converter via the 2-pin wire? I had assumed that wire provided power to the 8220...but I guess if it is tied to the power jack on the board, power would flow through both. Any thoughts on a power supply since the 8220 doesn't come with one? I was thinking maybe one from a USB hub. Do you know if the center pin on the power connector is positive?

Also...I noticed your web page says "or lo-res EGA"...can you clarify that statement? Would be even more awesome if this thing would do EGA conversion too...

Sorry to keep pestering you with all the questions... :)

Just sent an order your way for the board...many many thanks again! I'm very excited...

Thanks,

Wesley
 
I have several 8220 cables.
So for example, could I simply take two of the 2-wire cables and solder the bare ends together so I end up with a single wire with connectors on both ends?
That would make it much easier than going through the crimping.
 
Steve,

The 8220 should have come with 2 different cables, both with connectors pre-attached to one end. One of the connectors has 2 wires, and is for power. The other has 6 wires, and is for sync and data. Each of them will need a connector, as specified on my assembly page, attached to the other end, which comes from the manufacturer bare.

Thanks!
- Alex
 
ajacocks said:
All,

I now have stock of the boards and parts kits, and I have updated my inventory page, on the blog.
Click to expand...

I've placed a kit order. Looking at the specs for the GBS-8200 and GBS-8220 the only difference I can see is the second VGA output. Does anyone have any reason to believe the 8200 wouldn't work with this?
 
I'll also have to chime in and say it works great! At least on an IBM Compatible with CGA graphics...I don't own a C128. I can't tell you how awesome it is to be running on a VGA monitor off the original video card on my old Tandy...

Thanks,

Wesley
 
Was I supposed to get the connectors for the wires from the GBS-8220 to plug into DAC board? I got the connectors that go on the board, but not the connectors that plug into it. :)

Heather
 
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