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Need instructions for Enhanced Cable Tech "Liberty" VGA adapter....

Hi!

I'm trying to get my old PowerMac 8500 up and running. The only display I have that is (well, should be...) compatible is an old Apple Studio Display 15" Flat Panel (Rev B.). This is the second iteration of that display, with the VGA connection, not the earlier Mac 15 pin D-sub connection, which is what the 8500 has ( http://support.apple.com/kb/SP135).

I have two adapters that I'd think should do the trick of getting me something on the display. An NEC MultiScan unit that has several resolutions printed on it, but no adjustments, and an Enhance Cable Technologies Liberty adapter.

The NEC one gets me noplace, and so far, neither does the Liberty.

The Liberty has a knob with several letter stops (A-M or N), and a set of 9 (I think) DIP switches. Instructions on the back list many resolutions, but only give instructions for the last 3 DIP switches, which are for sync. It mentions to consult the instructions (which I can't find or don't have) for using the other DIP switches to get "expanded" ID codes.

I've tried all of the knob stops, and a couple DIP switch settings, but nothing seems to get me an image on the display. The display does work, it just isn't detecting a signal, and it will tell me so.

I think the 8500 may be going into "headless" server mode (no video) when it can't detect a monitor attached, so once it boots (and it IS booting), I can't get anything until I re-boot again. I'll have to dig up an OS9 install CD, to see if that helps me any. When I stored it some years ago, it was running Mac OS X 10.2 via a boot loader (it has a Sonnet PPC G3 processor upgrade card), so that may be an issue, too.

But, I was hoping that maybe someone has the instructions for the Liberty adapter kicking around in their junk drawer. All I need is the instructions for the DIP switch settings.

Regards,

Larry W.

PM 8500, Mac OS X (10.2.x), Apple Studio Display (G3 colors)

Posted on Feb 22, 2011 10:44 AM

Reply
6 replies

Feb 22, 2011 1:31 PM in response to Grant Bennet-Alder

The Apple Studio Display and the 8500 share most of the same set of resolutions. from 640x480, up to the display's native 1024x768. At this point, I'd settle for anything that gets me an image on the display.

Yes, I can use a multimeter, but I'm hopeful that someone has the instructions for this once-common adapter, so I can avoid the tedium of checking all the pins and switch settings and permutations thereof.

Feb 22, 2011 1:32 PM in response to Larry West

I assume that you're connected to the onboard DB-15 monitor port (which has a maximum of 4 MBs of VRAM), as opposed to a PCI graphics card - which could have a problem of its own. While a dead PRAM battery can cause a lack of video signal, unless you're connected directly to the DB-15 monitor port, you can't rule out the Mac-to-VGA adapter as the problem. The "Liberty" adapter that you've described sounds a lot like one sold by Belkin years ago, that I still have. It had a rotary switch and (8) DIP switches. If that matches the one you're using, here's the manual with settings from Belkin Support. A new 3.6-volt, ½AA lithium battery might be a good investment, if you plan on using the 8500.

Feb 22, 2011 1:40 PM in response to Larry West

the tedium of checking all the pins and switch settings and permutations thereof


If it came to that, it would only be pins 4, 7, and 10 (the ID bits) and one of the grounds. Despite how many switches there are, the settings for the ID bits are the only ones that change.

The VGA signals {Red, Green, Blue, and their grounds, H-Sync and V-Sync and their one or two grounds} all must be present to make a picture.

Message was edited by: Grant Bennet-Alder

Feb 27, 2011 8:26 AM in response to Larry West

Well, bought some new PRAM batteries from OWC. Installed one on the 8500/150 (also bought spares for my G4 & SE/30), zapped the PRAM several times, and still nothing. Then dug out my DVI-VGA adapter for my MBP, just to verify that nothing had gone sour with the display since I last put it in the box. All good there.

But, it turns out that I had a solution all along in the "Accessories Kit" in the box the Studio Display came with. There was, still sealed in 16-year-old plastic, an adapter that came bundled with the display! Cut open the plastic, installed it, hooked on the display, and presto-chango, I'm watching Jaguar boot up!

Though, Jaguar isn't so swift on this machine, even with a 250Mhz G3 processor... Might have to do with only 240MB of RAM... Once I got it back running Mac OS 9.1, though, it's a pretty snappy machine. It even reports a processor speed of 279Mhz!

Now I can get what I need from the machine, and move it on to a new home. Also check out all the rest of my SCSI devices for data I think I need, as this is my last SCSI machine that'll take more than one internal device!

And I may even see if I can make the Liberty adapter work like the Apple-supplied one.

Need instructions for Enhanced Cable Tech "Liberty" VGA adapter....

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