Connecting old Apple monitor to modern video card solved

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Joined: Dec 20 2003
Posts: 354

I've been trying to connect a Macintosh Color Display (M1212, 640x480 @ 66.7) to a Cube. I have finally succeeded, and wanted to share in case anyone else ever wants to do something like this and doesn't want to source an adapter or has an adapter which is incorrect for your particular monitor.
While monitor pinouts for DB15/HD15 are common knowledge, I found this particular adaptation to be confusing, and resources on the web extremely scarce. There is one Apple Developer doc that *hints* at a solution. My first dozen attempts at wiring it myself failed, and the first adapter I tried (590-0322, for 17 inch multi-scans I think) didn't work, even after cutting it apart and trying some re-wiring. The proper adapter that I should have gotten to begin with is the 590-1120. Testing for continuity on all pins reveals the solution:

DB15 HD15
1 6
2 1
3 13 (HSYNC)
4 4 (ID 0, when adapter is attached)
5 2
6 7
7 15 (ID 2, when adapter is attached)
9 3
10 12 (ID 1, when adapter is attached)
12 11 and 14 (VGA ID and VSYNC)
13 8
14 10 and 5
15 connects with DB15's 3

This was the same as 590-0322, except that the GND on 14 went to 10,5, and 11. I was able to make this adapter work with my monitor simply by snipping HD15's 11 and jumpering with 14.

Although Apple's Doc for its powerbook G3 adapter (the doc for the Cube's adapter, different part number, does not mention this) mentions that the computer looks to pin 11 first- if it is attached to VSYNC, it knows the adapter is attached and it looks to the traditional monitor IDs.

What I found to be not-so-obvious, and why I guess my own wiring didn't work at first, are the connections between 14 to 5 and the V and HSYNC connections. I had assumed that a DB15 monitor only takes composite sync so I didn't hook those up- I just combined them into pin 3 (which has worked for others, like in the iMac/Color Classic hack). Something about this didn't work here, perhaps because the link with pin 11 would become composite and not VSYNC, causing the computer to not realize that it should be looking at the old-style ID pins. Perhaps something inside the sizeable monitor cord connector keeps that signal from flowing back up the wire- after all, the only signal going to the a/b is composite (I've dug around in there), so it gets combined in the cord.

I hope this helps somebody avoid having to buy an adapter, or to be able to fix an existing adapter that is for a different monitor. I'm also interested in learning more about how the sync stuff works, if anyone knows.

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Joined: Dec 20 2003
Posts: 354
Ack! I can't edit the post

Ack! I can't edit the post >:( so I'll have to add here: my careful spacing in the wiring chart was taken out in the posting! Sorry if it looks confusing, not my fault. The second column of numbers should be lined up under "HD15."

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davintosh's picture
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Joined: Dec 20 2003
Posts: 554
How about...

... a Griffin gView adapter?
http://www.griffintechnology.com/products/monitor_adapters/
I've had good luck with the gView working with a lot of really old monitors. It's a bit spendy -- $50 -- in some cases it'd be cheaper to buy a different monitor.

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eeun's picture
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Joined: Dec 19 2003
Posts: 1891
[code]DB15 HD151

<br />
DB15   HD15<br />
1         6<br />
2         1<br />
3         13 (HSYNC)<br />
4         4 (ID 0, when adapter is attached)<br />
5         2<br />
6         7<br />
7         15 (ID 2, when adapter is attached)<br />
9         3<br />
10        12 (ID 1, when adapter is attached)<br />
12        11 and 14 (VGA ID and VSYNC)<br />
13        8<br />
14        10 and 5<br />
15        connects with DB15’s 3<br />

.
.
.
Wink {code} text here {/code}
I only remember that from struggling with the same problem in the old forum.

And thanks for sharing your adventure. I've still got one of those monitors (somewhere) and might need that chart.

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