Need iMAC G5 monitor hack (-> get input)

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renorave's picture
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Need iMAC G5 monitor hack (-> get input)

Just one year ago I spoke with one guy who sold his iMAC (last generation G4 with 17") with a nifty change:
You could hook up an video signal so it was displayed on the screen. I believe it must have been then a digital signal.
Who knows more about it. Unfortunately I lost the email address of this person.
To put the ideas further: I just bought an iMAC G5 with 20" screen and I would like to use this machine with my G5 Dual as backup and workhorse:
1. The screen when needed as additional viewing part for the main screen of my G5
2. The computational power of the iMac via iGRID (see also my forum topic in "Software Hacks")

With this you could have everything neatly in one place (wired with Firewire over IP or Ethernet) and have a multitude of uses which a solitude screen (eg. 20" AL Cinema Display) doesnt offer. (The new Mac Mini is only G4 power and further iMACs might even have Dual G5 Power)

I think it is worth digging for it.

Just another idea: the monitor cable hooks into the motherboard with a specific clamp. This opens perhaps the door for a hardware workaround if the software hack doesnt seem to be available or feasible. You would need the electric definition of every pin of this clamp, but this shouldnt be too difficult to find out. Also a sort of "semi-auto-switch" like available for USB Bus systems would do the the switch-over between internal use for the iMAC G5 and external input from any other source.

Please let me know what you think and know. I am happy to share every further developments with you.

renorave

Jon
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The only feasible way to have

The only feasible way to have the PMG5 display on the iMac would be something like VNC. Software only. The idea of hacking the LCD cable to use a more standard connection such as VGA is old and is quite impracticle. It would most likely cost more money to buy the cables and conversion circuitry than to just buy a decent LCD monitor.

Others will likely chime in with advice, but going software only is the only really viable option.

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Software - good!

Thanks Jon,
for the comment and hint towards "VNC". But I dont know what VNC stands for - sorry to admit. Do you have more detailed information about where to go or to ask if this could be a feasible monitor hack?

All the best

Oliver
(renorave)

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.

realvnc.com

VNC Rocks :coolmac:

mak

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Is that all?

I checked on VNC. They look like a remote desktop utility to me and they are in very beta status (they write about the latest version of VNC client, that it is "..very buggy". So, for the time being this doesn't help much. BUT, I will give it a chance and let you know about the results.
Please - you all out there knowing other possibilities - please still write and share your thoughts!

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Try these combos
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I use OSXvnc (http://www.reds

I use OSXvnc (http://www.redstonesoftware.com/osxvnc/OSXvnc.html) to remotly control my 1997 G3 MiniTower from my MDD G4. It works really well, i've never has a problem with it.

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I give it a shot, but ...

... can you work with your second cpu (in my case a iMac G5) to use the screen seemlessly while working with, say Final Cut Pro. I want to use the screen of the iMac G5 as it was a regular screen. With other words controlling is nice, but can I use the screen of the iMac if it were a second screen hooked onto my Dual G5! With VNC it looks like I have two separate brains with two separate monitors. I want two monitors to think in one unity and - if possible - have two machines working as being one brain (which might be possible one day with Apples XGrid Technology).

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no practical way to use . . .

a G5 iMac's screen as a simple display. The LCD driver circuits are integrated with the iMac's logic board (just like with a 'Book.)

I'm not saying it's impossible simply because some wise-acre is gonna call me on it. With the right LCD driver you could drive the iMac's display from an external source, but for the time and $$$ cost one could just buy another display.

hth,

dan k

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re: no practical way to use . . .

Now see, I just stumbled up against my knowledge limits. The service doc uses the term "TMDS video cable" and I don't know if that means its wiring is related at all to TMDS as used for external DVI display connections. Or is it, as I suspect, simply a very broad term which could describe almost any signal set feeding a modern LCD, kinda like LVDS as used with laptop displays?

So does the internal cable being TMDS mean it may be possible to drive the LCD from an 'normal' external DVI display signal source, or not?

BTW, the service pics show the LCD end of the cable attaching to a flat connector similar to those used with laptop displays. Does that mean anything? Also, based on those same grainy pics, it looks like the internal video cable may be around 20 wires, give or take a few.

dan k

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DVI or not, that is the question...

.. Dan, seems to be that it could be possible just to bypass the regular video cable by just connecting the 20pin clamp. Would it be great. Soldering a DVI socket to feed it from another computer seems to be tempting. Is there a way that you deliver me that information sheet you have??! I will collect all information here (VNC software solution, clamp alteration etc.etc.) and post it here with my quoting. I believe the monitor quality of the iMac makes up to the effort. Also it is fun, to find it out.

oliver

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Re: DVI or not, that is the question...

.. Dan, seems to be that it could be possible just to bypass the regular video cable by just connecting the 20pin clamp. Would it be great. Soldering a DVI socket to feed it from another computer seems to be tempting.

Ahh, but you can't just easily solder to those sorts of wires, as I recently found out. Here's a pic of a cross-section of a similar type of cable (TiBook.)
IMAGE(http://mywebpages.comcast.net/macdan/images/cable_ends.jpg)

Really tiny wires, each complete coax wire is only ~1/3 of a millimeter thick. Good luck doing anything useful with that! Now the iMac's cables are probably a little thicker, but I bet not much. Plus, LVDS/TMDS cabling is very sensitive, even with great care, I think it unlikely you'd be able to get a clean signal in there.

Is there a way that you deliver me that information sheet you have??! I will collect all information here (VNC software solution, clamp alteration etc.etc.) and post it here with my quoting. I believe the monitor quality of the iMac makes up to the effort. Also it is fun, to find it out.

The docs I have make very little reference to the cable itself, other than it's a TMDS cable. The cable BTW is part of the display and is not available separately. If you muck it up you'll have a tough time finding a replacement, the only source is gonna be from used/broken machines. There's gotta be lots of those around, right? NOT! Sad

Good luck, but in my judgement you're not gonna get anywhere with this hack. If you're a newbie about LVDS/TMDS stuff now, you're probably not a good candidate for pulling this off. If you want to learn more though, google lcd tmds "dvi-d".

dan k

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