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Topic: Apple Color Display to CC CRT VGA hack -- HELP! (Read 482 times) |
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tmtomh
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Apple Color Display to CC CRT VGA hack -- HELP!
« on: Jan 21st, 2003, 11:14am » |
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Hi all,
So as per an older thread here (which I read twice before starting), I've taken an Apple Color Display (13" Trinitron) and put it in a CC. More specifically, I've put the ACD main board (a/b), video board (thing at the end of the CRT in the little metal box), and yoke, and put it on a 10" CRT from a CC. The CRT is still in the CC, and the ACD's analog board is resting on the top edges of the plastic sides of the CC's inner frame.
I power on this contraption (via the ACD's currently disembodied power-on switch, which is still connected to the ACD's a/b), and the picture is shall we say distorted, as follows (sorry I don't have a digital camera):
There is a large circle on the screen. It takes up most of the screen, leaving only the corners outside its perimeter. This circle is greenish, and the background (the area outside the circle) is magenta-ish. It's almost like a cartoon spotlight is being shined on the screen from behind it. This weird screen image is also overlayed by five wide vertical bands that take up the whole screen-. They are of varying colors (usually some variation of repeating RGB), with relatively soft divisions between them.
Aside from this obvious difficulty, this "10 inch CC monitor contraption" works fine. It hooks up to a Mac and all the desktop icons and text are readable. The Monitors and Sound Control Panel shows it doing 640x480 @ 67Hz. Also, the screen image is not shimmery, and it doesn't change at all when I move the computer or (carefully) jiggle wires.
As far as I can tell, this is not a digital problem. This problem is completely in the analog realm. And both the ACD and the CC's video were working perfectly previously to this.
Two other notes:
(1) I adjusted every adjustment I could--and I was actually able to get very good convergence in terms of text being sharp and no color fringes on the text or icons. I did some adjusting on the main board (there are about 12 pots for various things), the video board and the yoke. All controls work properly (size, center, brightness, contrast, R, G and B balance), but none impact this problem.
(2) I connected the ACD's two grounding wires to the CC CRT's grounding harness (they don't clip on like the CC a/b's wire, so I crimped them on and they're holding fine). Also, I spliced the end of the ACD's degauss cable onto the CC's degauss cable, as the CC's degaus connector doesn't fit on the ACD's main board. They both seem to be simple white-black wire setups, but the ACD's wires are solid inside the insulation, while the CC's wires are stranded.
So is the monitor just not degaussing when it powers up? I would tend to think that, except that (a) the vertical bands are very uniform and straight, and (b) the "circle" on the screen has pretty clean edges and looks very symmetrical. I always thought a magnetized screen had more irregular problems.
Any help here would be appreciated--GREATLY appreciated.
Thanks!
Matt
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| « Last Edit: Jan 21st, 2003, 11:19am by tmtomh » |
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StuartBell
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #1 on: Jan 21st, 2003, 12:31pm » |
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Based on my experience with a 575 yoke on a CC CRT, I'd suggest that you investigate moving the new yoke along the neck of the CRT, if necessary removing the rubber bumpers on the back of the CRT which limit forward travel of the yoke.
Stuart
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tmtomh
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #2 on: Jan 21st, 2003, 2:00pm » |
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That did it, Stuart--thanks!
I have a fair amount of adjusting left to do, but the circles and banding are gone! 
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Chris Lawson
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #3 on: Jan 21st, 2003, 2:19pm » |
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So to summarise:
You have successfully driven a 10" Trinitron CRT from a CC using the electronics from a 13" High-Res RGB display.
Right?
If so, there remains the problem of how to get the video signal from the CC's motherboard to the a/b from the 13" RGB display. Once that's sorted, it should be a reasonably simple procedure to build an Alchemy- or Gazelle-based Takky by using the 13" RGB analogue parts and a separate PSU, which would completely remove the CC's a/b from the equation, along with the mods its use entails.
cl
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Chris Lawson
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Trash80toG-4
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #4 on: Jan 21st, 2003, 5:31pm » |
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on Jan 21st, 2003, 2:19pm, Chris Lawson wrote:
. . . there remains the problem of how to get the video signal from the CC's motherboard to the a/b from the 13" RGB display.
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How about the mirroring slot in the 5290, there's a similar one on one of my 630 mobos, (the DOS compatible?) IIRC.
Is there a pin for pin correspondence between that slot and the MedusaMac harnesss for the older 575/CC or the 630 (580) and better PPC machines?
That might be a productive line of research.
jt
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| « Last Edit: Jan 21st, 2003, 5:32pm by Trash80toG-4 » |
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Chris Lawson
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #5 on: Jan 21st, 2003, 5:46pm » |
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on Jan 21st, 2003, 5:31pm, Trash80toG-4 wrote:
How about the mirroring slot in the 5290, there's a similar one on one of my 630 mobos, (the DOS compatible?) IIRC. |
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Well, I would just suggest pulling it out of the harness, since you need some way to get signals into the board anyway, and that harness/edge connector combo is the easiest way to do it 
cl
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Chris Lawson
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tmtomh
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Color Display to CC CRT VGA hack -- Update
« Reply #6 on: Jan 21st, 2003, 8:58pm » |
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Okay, here's the best I can get:
Screen size:
Top and bottom: negligible black bars -- 1/8" or less
Left and Right: borderline acceptable -- 1/4" to 5/16" black bars, measured from the edge of the plastic screen bezel.
Convergence:
This is a slight problem. For some reason, I cannot get the upper-right corner of the screen to converge properly. The blue gun is in the proper convergence position, but the red gun (and I suppose the green gun; not sure) "droops" ever so slightly in the upper-right corner, so that the righthand edge of the menubar, and the hard drive icon and label, have a slight red edge visible on their undersides and a slight blue edge visible just above them. Adjusting convergence at the video board and on the yoke has minimal effect on the problem while throwing convergence out of whack on the rest of the screen.
Fortunately, it's not a major problem--it's only visible when looking straight or from a severe downward angle (i.e. your eyes are much higher than the top edge of the screen). When looking at it from the angle most of us end up in -- your eyes just a bit above the screen so you're looking down slightly -- the problem is well within normal tolerances.
So I think my next step will be to fit my Performa 6214 harness, mobo and DB15 video board in the case and hook the ACD's monitor plug onto the 6214's video board. For this temporary setup, I will essentiall have an ACD and a 6214 hooked up together inside a CC case. I'm sure this sounds like a horrible, awful kludge, but if I can figure out how to get the ACD and 6214 PSU's to take just one AC plug and to both turn on from one switch, then I think it will be pretty cool. The monitor will still attach to the computer's mobo through an "external" connection, but the whole thing should be able to fit inside the CC case because of all the extra room freed up by using the ACD main board, which is much smaller than the CC's a/b. Besides, that's how the original iMac's monitor was hooked up to its mobo. 
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| « Last Edit: Jan 21st, 2003, 9:57pm by tmtomh » |
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tmtomh
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #7 on: Jan 21st, 2003, 10:13pm » |
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on Jan 21st, 2003, 2:19pm, Chris Lawson wrote:So to summarise:
You have successfully driven a 10" Trinitron CRT from a CC using the electronics from a 13" High-Res RGB display.
Right?
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Well, yes, as long as 1/4" black borders on the left and right don't disqualify it from being called successful.
Also, I haven't tried putting the back of the CC on yet, but I suspect that there might be a slight problem with the ACD's main board sticking out the back a little bit. The board's small, but a couple of the wires connecting the video board (the thing stuck on the back end of the CRT neck) to the main board are a bit short, which limits one's ability to shove the main board forward toward the front of the CC case. But, as always, folks who are more competent at this stuff than I am will have no problem splicing in some AWG20 or 22 wire to lengthen these couple of connections.
Quote:
If so, there remains the problem of how to get the video signal from the CC's motherboard to the a/b from the 13" RGB display. Once that's sorted, it should be a reasonably simple procedure to build an Alchemy- or Gazelle-based Takky by using the 13" RGB analogue parts and a separate PSU, which would completely remove the CC's a/b from the equation, along with the mods its use entails.
cl |
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Well, as I noted in my previous post, my quick and dirty idea is to just use the ACD's external monitor cable to hook into the Alchemy's or Gazelle's (or in my case, the Codycep's) video daughterboard. For those of you out there who, unlike me, are adept at splicing and/or rebuilding cables and/or making custom connectors, you could easily shorten the ACD's video cable to just a few inches, and the whole thing would easily fit inside the case. It seems a whole lot easier than wiring the tiny little ACD mainboard video connector into the appropriate pins on the wiring harness.
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StuartBell
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #8 on: Jan 21st, 2003, 10:43pm » |
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on Jan 21st, 2003, 10:13pm, tmtomh wrote:
Well, yes, as long as 1/4" black borders on the left and right don't disqualify it from being called successful.
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Just a thought; presumably you're using a 'Hi-Res' display at 67Hz? I just wonder what would happen if you fed the a/b a VGA signal at 60Hz refresh? It might refuse to display anything. Or might it give a wider display area? Just a wild wondering!
Stuart
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tmtomh
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #9 on: Jan 22nd, 2003, 5:10am » |
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on Jan 21st, 2003, 10:43pm, StuartBell wrote:
Just a thought; presumably you're using a 'Hi-Res' display at 67Hz? I just wonder what would happen if you fed the a/b a VGA signal at 60Hz refresh? It might refuse to display anything. Or might it give a wider display area? Just a wild wondering!
Stuart |
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Yeah, good question. That was my first thought, except I don't know how to feed the a/b a 60Hz signal. The Monitors and Sound CP shows only the 67Hz option, and the "show recommended resolutions" pop-up menu doesn't have the usual option to change it to "show _all_ resolutions." I might try SwitchRes (which is supposed to allow you to choose more resolutions than Apple's own control panel does), but I'm not optimistic -- I think it might be a hard-wired thing. But we'll see.
While I'm on the subject of this hack, anyone have any (hopefully simple) ideas about how to get the ACD's PSU and the PSU of whatever computer mobo I put in there to act as one? Aside from relay issues, there's no way in h@#$ that I'm going to be able to plug an AC cord into the back of the ACD main board without gutting a giant hole in the rear of the CC case. And then there's also the ungainly matter of the ACD's on-off solenoid switch assembly -- I'd love to ditch that too.
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StuartBell
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #10 on: Jan 22nd, 2003, 7:19am » |
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on Jan 22nd, 2003, 5:10am, tmtomh wrote:
- I think it might be a hard-wired thing. But we'll see.
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It is. You need to make the logic board think it's driving a VGA display, by altering the sense wires, then the System will offer VGA as a display mode.
Stuar
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tmtomh
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Color Display to CC CRT VGA hack--another update
« Reply #11 on: Jan 22nd, 2003, 8:14pm » |
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So now I've got the Perf6214 wiring harness, speaker and mobo in the CC's chassis. A Western Digital 8.5GB IDE hard drive I had lying around is in there as well (the SCSI cable coming off the 6214's harness isn't connected to anything).
Also in the case is the 6214's video daughtercard, which connects to a 34-conductor ribbon coming off the harness, and provides a normal Mac DB15 monitor port. Plugged in to that port is the "external" video cable from the ACD. The 6214's speaker also plugs in to the 6214's video daughtercard (rather than the harness or the mobo).
Outside the chassis--because I haven't lengthened the appropriate ribbon cables -- are the 6214's PSU and fan.
When I try to boot this contraption, the fan and hd spin up, and the hd makes the first noises a hd makes. But there's no startup bong and no video.
The problem, I believe, is one of two things: either (1) the dead PRAM battery is preventing the video from starting up, and since the speaker connects via the video daughtercard, also prevents the speaker from working; or (2) for some as-yet-unknown reason, the video daughterboard just doesn't work in this setup, even though it worked fine when it, and the harness and mobo, were in the 6214's case.
My guess is that it's just the PRAM battery.
So this is all looking rather promising I think, with one major exception: power. I'm sure for some folks here this is an easy one, but for untalented ol' me, it's a real issue. I've got two separate PSUs, one of which won't fit in the case until I lengthen its (proprietary?) 14-conductor ribbon, and another of which I can't plug an AC cord into without mutilating the back of the CC's case. I'm also a little skeptical about fitting the 6214's PSU in at all, though it must be possible given the Takky's that many folks have already created.
So I assume that the way to deal with the PSU issue is to have the AC cord plug into the 6214's PSU, and then hook up a relay between it and the ACD's PSU. Is that right? If so, um, how the heck do I do that exactly? Is it just a matter of tapping into the three-conductor wire that connects each PSU's circuit board to its AC plug?
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Chris Lawson
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #12 on: Jan 23rd, 2003, 8:09pm » |
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on Jan 23rd, 2003, 6:47pm, ccc_trix wrote:| A relay? If there is a power plug that fits the CC case (attached to the a/b, PSU or just stand alone), couldn't you solder some wires from it to whatever needs 120V AC power? |
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Rather inefficient since that keeps the a/b powered on all the time.
However, if you use a 120V relay, it should be a simple matter of putting the switching side on the CC's plug and connecting the switched side (the side controlled by the power pins of the relay, rather than the power pins themselves) to the a/b of the monitor. You'll want at least a 5A relay and possibly a 10A one depending on what the rating on the monitor is; I don't remember.
cl
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Chris Lawson
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Chris Lawson
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #13 on: Jan 24th, 2003, 4:51pm » |
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on Jan 24th, 2003, 4:45pm, ccc_trix wrote:| I don't really understand why a relay is needed though. |
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To save you the trouble of reaching for two switches 
Quote:| Will any monitor pull more than 5A? |
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It wouldn't surprise me. 5A at 120V is roughly 600W, and whilst that sounds a bit high, it never hurts to over-engineer a bit.
cl
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Chris Lawson
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Chris Lawson
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Re: Apple Color Display to CC CRT VGA hack -- HELP
« Reply #14 on: Jan 24th, 2003, 5:33pm » |
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on Jan 24th, 2003, 5:04pm, ccc_trix wrote:| Yes but why can't you have one switch and splice it's output to two things, rather than using a relay? |
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If the switch can handle that, you could, but the way the CC is set up, when you turn it on, it doesn't actually turn on the computer. It just turns on the analogue board's degaussing circuit. Once the power-on signal is received, the degausser turns off and everything else turns on.
cl
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Chris Lawson
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