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samsonlonghair
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Re: Early Intel iMac - Repair it or mod it?

by samsonlonghair Fri Dec 22, 2017 10:58 am

CRTGAMER wrote:One area to check if possible is the amp draw of each monitor. Should be similar, suspect the newer LG with more efficient circuits should have less amp draw. There is a risk of blowing out your motherboard if the signals all do not match. On the other hand, if the power lead is another isolated connection a better shot. Apple's reputation of proprietary a concern if all the pins are electric feed identical. A volt read of each pin from both the Apple and LG boards might help, but then it is still a guesstimate.

Good point, CRT. Luckily for me, most of the amperage is drawn through the other wires.
samsonlonghair wrote:Image
These electric lines connect the inverter to the cold fluorescent lamps that light up this display. :idea:

See these wires? These are the ones that draw power the necessary to light up the display. This is where most of the electricity is consumed. The iMac has its own invertor that supplies DC power to the whole machine, not just to the LCD panel. If I understand correctly, the backlight lamps should only draw as much power as they need.

As far as the electrical draw of the LVDS connection, that's the part I'm least concerned about. LVDS is first and foremost an electrical standard. Texas Instruments published a paper on LVDS that explains the electrical specifications better than I can.
An Overview of LVDS Technology (adobe .pdf file)
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samsonlonghair
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Re: Early Intel iMac - Repair it or mod it?

by samsonlonghair Wed Dec 27, 2017 2:01 pm

Update: I poured a lot of work into this project over Christmas. I had to modify the LVDS cable a little bit, but not much. I also took the time to upgrade the processor, flash a newer firmware, and install an SSD.

I think I'm just about ready to put everything back together. In theory, it should work better than new. Cross your fingers, wish me luck, and knock on wood. I'll take a few pictures when I get home.
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samsonlonghair
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Re: Early Intel iMac - Repair it or mod it?

by samsonlonghair Fri Dec 29, 2017 2:19 am

Dig this!
Image

How do you like it?
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CRTGAMER
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Re: Early Intel iMac - Repair it or mod it?

by CRTGAMER Fri Dec 29, 2017 10:58 am

samsonlonghair wrote:I had to modify the LVDS cable a little bit, but not much. I also took the time to upgrade the processor, flash a newer firmware, and install an SSD.

Blah Ha, Congrats! Looks factory, great job.

Concerning the LVDS cable, were any pins moved around or just making the different connector match up? If you have the modified pin layout on paper perhaps a picture of it for future reference?
Image
CRT vs LCD - Hardware Mods - HDAdvance - Custom Controllers - Game Storage - Wii Gamecube and other Guides:
CRTGAMER Guides in Board Guides Index: http://www.racketboy.com/forum/viewtopic.php?p=1109425#p1109425

Image
Image
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samsonlonghair
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Re: Early Intel iMac - Repair it or mod it?

by samsonlonghair Fri Dec 29, 2017 11:15 am

CRTGAMER wrote:
samsonlonghair wrote:I had to modify the LVDS cable a little bit, but not much. I also took the time to upgrade the processor, flash a newer firmware, and install an SSD.

Blah Ha, Congrats! Looks factory, great job.

Concerning the LVDS cable, were any pins moved around or just making the different connector match up? If you have the modified pin layout on paper perhaps a picture of it for future reference?


Thanks, CRT! That's what I was aiming for. I wanted that stock iMac look. :D I'm glad you like it.

No pins were different, thank goodness! I didn't need to rewire anything. I just had to trim away the plastic around the edge of the connector for a better fit.

I learned a lot about the inner workings of an iMac from this project. I also have room for improvement. I think I might like to work on another iMac again in the near future. Maybe I will hit up Craig's List to see if anyone is selling one locally. :mrgreen:
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Re: Early Intel iMac - Repair it or mod it?

by CRTGAMER Fri Dec 29, 2017 11:57 am

samsonlonghair wrote:Image

Google seems to indicate that there are a number of monitors that use the exact same LCD panel. The cheapest one I could find was the LG Flatron W205TQ for $20. I went ahead and picked it up on the 'Bay when I saw it for sale.

I had to modify the LVDS cable a little bit, but not much. I also took the time to upgrade the processor, flash a newer firmware, and install an SSD. No pins were different, thank goodness! I didn't need to rewire anything. I just had to trim away the plastic around the edge of the connector for a better fit.

I learned a lot about the inner workings of an iMac from this project. I also have room for improvement. I think I might like to work on another iMac again in the near future. Maybe I will hit up Craig's List to see if anyone is selling one locally. :mrgreen:

That is sweet. I included your earlier picture that shows the difference. Suggest posting this suberb fix on any major iMac Forum site, get the word out! Replacement 17" and 20" LCD widescreen monitors are plentiful and inexpensive at Thrift and Recycle Center stores.

Now if there were a similar guide for the earlier G3 CRT combos, some have a history of the video failing. Usually an over saturated pink screen caused by the PCB failing and not the tube though.
Image
CRT vs LCD - Hardware Mods - HDAdvance - Custom Controllers - Game Storage - Wii Gamecube and other Guides:
CRTGAMER Guides in Board Guides Index: http://www.racketboy.com/forum/viewtopic.php?p=1109425#p1109425

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Image
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Re: Early Intel iMac - Repair it or mod it?

by isiolia Fri Dec 29, 2017 1:06 pm

samsonlonghair wrote:How do you like it?


Lookin' good - I wound up looking more into the panel for the one I have, since it will apparently run up through 10.11.x I guess due to having a discrete GPU. My otherwise-similar vintage 2007 Macbook topped out at 10.7.5. Wound up ordering one on eBay, since a handful of sellers are actually pricing them reasonably ($46ish) and some RAM, so we shall see how it goes.

I kinda tore the original down a lot trying to see what caused the issues it had, but nothing I could seem to fix. /shrug It's actually a layer behind the LCD itself, and the portions that didn't bubble up are still quite attached.
Image

Meanwhile, I zeroed the HDD and installed 10.7, keeping it on for a day or so with no issues...so I think the base machine is fine.
Image

Otherwise, while I was visiting family, I acquired several old PC towers to add to the couple of mine I still had. Primary thought is to get decent Windows 98SE and XP machines set up, but I have a lot more hardware leaning into the Vista/7 type era. Probably a different thread for that stuff though.
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Re: Early Intel iMac - Repair it or mod it?

by Michi Fri Dec 29, 2017 1:44 pm

samsonlonghair wrote:Dig this!
Image

How do you like it?

Awesome job, Samson. Looks slick.
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Re: Early Intel iMac - Repair it or mod it?

by samsonlonghair Fri Dec 29, 2017 1:46 pm

CRTGAMER wrote:That is sweet. I included your earlier picture that shows the difference. Suggest posting this suberb fix on any major iMac Forum site, get the word out! Replacement 17" and 20" LCD widescreen monitors are plentiful and inexpensive at Thrift and Recycle Center stores.

Thanks, CRT! I appreciate your vote of confidence. :mrgreen: You know what they say, "Necessity is the mother of invention," Right? I've been impoverished most of my life. (who am I kidding? I'm barely above the poverty line now! :lol: ) I learned early on the value of fixing what's broken instead of throwing it away. My grandfather taught me that we live in a "throwaway culture" where nearly everything seems disposable, but if you invest your time and sweat into fixing something you get an even greater value. Sometimes this requires a stubborn personality because it's always easier to quit and give up when you hit a wall. You just have to get creative and improvise until you come to a solution. The solution isn't always obvious, but if you keep attacking the problem from different angles, you just might figure it out.

Don't get me wrong, it ain't all "grampa wisdom" and gumption. :lol: I also use google and ifixit just like everyone else.

Troubleshooting
CRTGAMER wrote:Now if there were a similar guide for the earlier G3 CRT combos, some have a history of the video failing. Usually an over saturated pink screen caused by the PCB failing and not the tube though.


Hmm... This is an interesting problem. I don't have a lot of experience working on Cathode Ray Tubes, but I'm sure you're familiar with them, eh CRT? :wink: I understand you own more than one G3 iMac, right? Do any of them have a pink screen problem such as you described? If so, what's the model number and emc number? I'd like to look into it out of curiosity.

Before we say for certain that this Pink Screen issue is a hardware problem, let's make absolutely sure we rule out software problems. What if the problem isn't actually in the CRT display itself? Maybe this comes down to the instructions that the Mac is using to communicate data to the display. It never hurts to try zapping the PRAM and the NVRAM. That's a simple quick fix that works more often then one might guess, and there's practically zero risk to harm your system. Might as well rule out simple things before we progress to more complicated things.

I'm assuming you probably have OS9 installed in a dual boot configuration, right? I would try booting into both OS9 and OSX. You might also try booting to a target disk in another mac. Do you have the pink screen on both operating systems? If not, then you have found where your problem lies. If the Pink Screen persists irrespective of the operating system, then I think we need to look at the firmware next.

I have heard that some of the G3 iMacs need a firmware update, or conversely, that they need to be restored to their previous firmware. This would probably be a job for OS9 I think. Make sure you download all the different firmware revisions for your G3 iMac. Have them handy on a flash drive or burned to a CD-R. Try the most recent firmware first. If that doesn't alleviate the problem, move onto progressively older firmware. If none of these works, make sure to re-reinstall the newest firmware at the end of this step. Newest firmware is nearly always the best firmware.

Once we rule out the Software and the Firmware, let's move onto the hardware. From here we remove the internal monitor and try to replace it with compatible parts. Standard disclaimer: Be careful; CRT monitors can carry enough charge to harm/kill a careless person. I'm sure I don't need to tell you that, CRTgamer.

I think I mentioned before that older tray-loading G3 iMacs have an internal VGA connection buried inside the machine. I failed to mention that back in the day, Apple used a proprietary connector for VGA signals. Sound familiar? :roll: Apple's gonna apple. The old school Macintosh VGA connector is fifteen pins just like every other VGA connector, but it's shaped a little differently. Instead of three rows of five pins, The Macintosh video connector has two rows of pins (eight on one row, seven on the other row). The one in a G3 still transmits a VGA-compatible signal, you just need to source a cheap adapter. These used to be more common back in the day, but I haven't spied one in a few years. Looks like this:
Image
more info on the adapters here: http://www.retrotechnology.com/herbs_stuff/mactovga.txt
If you can find one of these adapters, you could replace the monitor inside a tray-loading G3 iMac pretty cheaply.

Edit: Found more info on connecting a VGA monitor inside a tray-loading iMac here:
http://lowendmac.com/mail/mb07/0725.html
Last edited by samsonlonghair on Fri Dec 29, 2017 2:16 pm, edited 1 time in total.
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samsonlonghair
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Re: Early Intel iMac - Repair it or mod it?

by samsonlonghair Fri Dec 29, 2017 2:10 pm

Michi wrote:Awesome job, Samson. Looks slick.

Thanks Michi! I'm glad you dig my iMac. It means a lot to me. :mrgreen:
isiolia wrote:Lookin' good - I wound up looking more into the panel for the one I have, since it will apparently run up through 10.11.x I guess due to having a discrete GPU. My otherwise-similar vintage 2007 Macbook topped out at 10.7.5. Wound up ordering one on eBay, since a handful of sellers are actually pricing them reasonably ($46ish) and some RAM, so we shall see how it goes.

Thanks, Isiolia!
Ordering a Macbook or ordering an iMac on eBay? Either way, I'd love to see some pictures when it comes in.

I'm glad you're working on that iMac. Good luck on your project; I can't wait to see how it turns out. 8)

isiolia wrote:I kinda tore the original down a lot trying to see what caused the issues it had, but nothing I could seem to fix. /shrug It's actually a layer behind the LCD itself, and the portions that didn't bubble up are still quite attached.
Image

I can honestly say that I have never seen that before. Maybe the layer of plastic got too warm? If you run a hardware diagnostic, does it report back that the iMac has ever overheated? Just spit-balling here.

isiolia wrote:Meanwhile, I zeroed the HDD and installed 10.7, keeping it on for a day or so with no issues...so I think the base machine is fine.
Image

Awesome sauce! I am so happy that your iMac is still running without the display. They're cool-looking when you can see their interiors, aren't they? Also, I like that Mac keyboard with the black keys. Looks slick!

A couple ideas off the top of my head: What if you upgrade to a better monitor than the one that originally came in that iMac? For instance, what if you dropped in a higher-resolution monitor, or a touch-screen, or an HDR screen? How about a screen with a wacom stylus so you can draw right on the screen. If you're not super-concerned about keeping your iMac looking stock, you could add all kinds of creative features that Apple never saw fit to add to the iMac.

isiolia wrote:Otherwise, while I was visiting family, I acquired several old PC towers to add to the couple of mine I still had. Primary thought is to get decent Windows 98SE and XP machines set up, but I have a lot more hardware leaning into the Vista/7 type era. Probably a different thread for that stuff though.


You know what? I think I'm going to update the first post and the title of this thread. Now that I completed the original project, It's time to broaden the scope of this discussion. Plus, I want to hear the input of our other forum members. You clearly have experience working on Macs, Isiolia. I think Fast mentioned modding a G4 iMac. I'd love to hear more about that and see some pictures. :mrgreen:
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