Let me introduce you to my new favorite form factor: The Embedded Compact or ECX. When I took this out of its box, even though I knew its dimensions, I was shocked at how small it was. I do want to caution that everything with these boards is proprietary including its cables and proprietary = expensive. So know what your getting yourself into. I've seen these available in either Atom or most excitingly Mobile Core 2 Duo configurations as this one is.
In terms of features you can see the PCIe x 4 slot, a DVI/VGA/HDMI out. However, there is actually an LVDS out as well inverter pins (yes the entire LCD conroller is embedded in this tiny motherboard). So you could connect the LVDS cable and inverter directly to this motherboard without any additional hardware. Now the question is can the native LVDS resolution drive the iMac's 20" screen? And does this solve the problem with the inverter for the 20" iMac - maybe?
The underside shows the RAM (4GB) in place (purchased separately) as well as a slot for a Compact Flash Card. This I also find to be a fantastic addition. I need all the space I can get and although I am not sure, I would be surprised is an embedded board was unable to boot from the compact flash memory. This could mean with a 64+gb card no need for a hard drive, no extra heat or power, and a much faster system.
Here is the 2.53 Ghz Core 2 Duo Mobile (Socket P Penryn Processor) and its very reasonably sized heat sink/fan.
This is the first board that I have felt makes an all-in-one doable. I have never liked the idea of shoehorning a mini itx or mac mini into the base at an angle. Plus I had extreme concerns about airflow. I imagine this sitting above the dvd drive with the cpu fan around the same place as the iMacs original fan. This board also allows incorporation of a dvd drive. Although not necessary anymore, I always felt it was part of the iMac's charm. In addition, if no other hardware is required that would leave the bottom for placement of a powerwave adapter (to use the original speakers) as well as extenders/ports to make the rear I/O look as original/professional as possible. It does use a power brick, but I am certainly ok with that as no internal powersource = less heat.
Now I could find this board impossible to work with, it may not fit at the top of the base, it may require a hard drive. I don't know, but keep this in mind the original iMac was an embedded compact motherboard, it only makes sense to use something along those lines.
I already know I can thread LVDS cables down the neck into the base with a replacement 20" LCD. However, I could also try to splice the existing panel to DVI. I'm not sure which way I'm going to go - but I am leaning towards LVDS (if the native resolution is compatible) as it is embedded onto the motherboard, thus will turn on/off with the motherboard etc. For people interested in doing this, you will need extra LVDS cable. The best place to get it is ebay. I find cables used in flat screen tvs are usually longer and of more use. Examples of LVDS cables from tvs are shown in the pic on the right.
The biggest problem I'm going to have is with that damn 20" inverter (I am not running high voltage cables through the neck again - too unsafe). Unlike the 15 and 17" I have not been able to get it to work independently. Although there are pins for the inverter on the motherboard, it is one short. I believe there is some voltage difference involving orange and yellow that turns the inverter on. I am hopeful that maybe by having an active dimmer hooked up that this may solve the problem. Obviously using the native inverter with the motherboard would be option number 1.
Option 2 would be to locate some other aftermarket inverter that will work. I have yet to find one that is "flat" enough to fit in the monitor casing, but I haven't looked for sometime.
Option 4 is using the 17". Although I'd prefer the 20", if getting the backlights to work on the 20" proves too difficult, I already know how to do so with the 17". And would be quite happy with a fully all-in-one modernized 17" iMac G4.
I'd love to hear advice from people who have some know how with led backlights etc. And as always I'd be happy to answer any questions.
Hi - great Blog!ReplyDelete
I am sorry but I can't find the exact description of this ECX board. Can you tell us the product number and the manufacturer?
In addition: I just realised your Option 3 - replacing the CCFLs to LED. I just exactly the same superbright LED stripes which you show there.ReplyDelete
Unfortunately my description is in German (http://www.brennecke.org/?page_id=485) but there are some photos, and of course I will answer any question :-)
The ECX board is made by a company called Quanmax. The product number is KEEX-4030. I purchased mine from a company called logic supply. Here is a link to the manual if you'd like to read about the featuresReplyDelete
And I am certainly interested in learning how to convert CCFLs to LEDs, it would make the entire inverter problem moot.
Thank you for the board number. In the mean time, I decided to go with an ATom270 Board, the Intel D945GSEJT, which also has an LSVD controller onboard (which seems to be disabled by default, grr). This board will fit into a completely empty G4 iMac housing.
As far as the CCFL-LED switch is concerned, I highgly recommend it and did it again today with a 17" TFT (Samsung LTN170X2-L02) which even did not require any Dremel action (only one CCFL). As you may see on the photos in my blog, there is one visible drawback: the "theater spots". I thought one could avoid these brighter spots by giving more space between LED stripe and backplate. But today I followed my idea with the new display and now it shows the same spots (well, they are not so bright as in the iMac 15"). However, they do not catch so's eyes when surfing in the Internet, but they might annoy you watching a movie or doing some office work the whole day.
I am currently working on a more sophisticated version of the "Inverter" board (which is currently only a current dispatcher). I would like to switch off the backlight and even dim it if possible.
JeanLuc, do you find the brightness comparable to CCFLs. Would it be possible to use LCDs to backlight just th LCD glass itself instead of edge lighting? I ask only because the decrease weight and thickness would allow me to fit a proper a good touchscreen such as a glass surface acoustic wave or capacitive screen. I appreciate your help.ReplyDelete
The board is a fine choice. I did try to fit a mini itx board or a previous mod - while it fits, it was actually the ports that I found frustrating. Plugging in the DVI cable and USB cables to the back of the board makes the board significantly longer. I had to use a dvi to right angle HDMI connector to save space.
Before you buy just take a look at the Keex-2030 ECX board. It has an identical atom n270 1.6ghz processor. Identical Intel G95GSE northbridge and ICH7M southbridge chipsets. They both use Intel GMA950 graphics and are both passively cooled. The ECX has a pciex4 while the mini itx has a mini pcie. The ECX also gives you an integrated compact flash option and an LVDS out ight on the mobo. They really are the same board, but the Keex is 14.2x10.6cm vs the
mini itx at 17x17cm. Plus you don't need a formal power supply. Just something to consider.
Thanks for the board recommendation. I will consider this. I already took a look at the KEEX-4030, but I found no vendor here in Germany. This might make things a bit complex...ReplyDelete
The LED's seem to be not as 100% bright as the CCFL, but this is more caused by the different color space. The ones I used seem to contain more blue and less red (which means a higher color temperature). So the overall impression is a bit different from the original CCFL. But on the other hand this is the same when you compare a standard older Apple Cinema Display with new LED monitors, so no real issue.
I dont' think it is very easy to change from edge lights to backside lights. The two TFTs where I replaced the CCFL with LED are built quite similar: There is a backside white plastic sheet, followed by a clear acrylic glass with some spots for light diverting. Then at last several silk-like coated white foils, also for diverting the light. In my understanding, they are prepared to take light from the edges, not from the backside.
You might give it a try. The best z-position is of course directly behind the acrylic plate – don’t know if the white back plate is still needed. Next the LEDs should be positioned closely together to avoid differences in brightness – this plate is only 3-4mm thick. This means to use a lot of LEDs - and then you probably have to dim then because these many LEDs will be much brighter than the ones from the edges (2x18 in my case of the iMac G4 15", only 23 in case of the Samsung 17" display). This might lead to the next problem: These LED stripes are made for 12V; they are grouped by 3 with a small resistor. Thus dimming will probably work only if you use a phase controlled modulation.
I just tried to fit an old MiniITX board into the iMac housing. While it fits into the bottom shell, it strangely covered some screw holes - which I apalledly identified as the four pillars of the dome. So in my understanding, the MiniITX will only fit in that housing with a tremendous milling. Any suggestions on that?
Otherwise I have to find a dealer for the KEEX-2030, which might be a quite similar effort than the milling ;-)
Trust me, grinding the faraday cage would be an absolute nightmare unless you have heavy duty equipment.ReplyDelete
Take the board a push it into the top half of the dome, you will see that at the right angle (about 45 degrees - so its like a diamond) you can get the board into the bottom. The problem I had is when I started putting connectors into the back ports. The ECX board really made my life a whole lot easier.
Let me know how you do - if you can not find it anywhere, I could try to price it for you here with shipping. Let me know.
Thanks - I found this 45° solution lately. Was stuck on the usual rectangular computer construction and did not think of this first. I started some inquiries for the ECX board anyhow, let's see if the board is available somewhere here in Germany.ReplyDelete
What's your opinion on the LED switch (My comment above)?
JeanLuc - there is no link to the 45 degree solution you had mentioned aboveReplyDelete
I just had a few hours spare time and got me an old 20" Cinema Display with that ADC connector (was sold as "defective"). Well, the stand was damaged but the display was still ok. However, I decided again to remove the CCFLs and replace them with LEDs. The 20" model is much thicker than the 15" iMac screen, and it uses 6 CCFLs, which means a lot space for the LED stripes. I completely removed them together with the Inverter and this time (with that much space in the CCFL housing) even these "theater spots" did not appear. The brightness could be a bit higher, but in a normal bureau surrounding with no direct light it's perfectly ok (with only 2x28 LEDs).
ADC displays operate with 28V on the inverter, so I decided to connect the two LED stripes in series. I also added a single-transistor solution to switch on and off the backlight re-using one of the inverter data cables with a 5V-level indicating the on-off state.
This all did not take more than two hours of work, I only had to take care of all the different screws and metal cages to put them back to their position.
There's one more thing with that Cinema Display. It contains a feature to detect the display's and the backlight's status, which means that it blinks 3 times telling me that there is something wrong with the backlight - which is actually corret because the CCFLs and the inverter board lie here before me outside the display :-) But that's a real minor drawback.
So if you go for LEDs in the future, there's only one thing with the 20" screen, and that is the reduced brightness.
Jean Luc - excellent work. When I took a long break from this mod I was because a year or so ago I figured that as soon as LED displays became more available and affordable this mod would become very easy. I figured I would just purchase a 20" led LCD and put it in the iMacs monitor housing. As the LEDs use DC voltage - no inverter is needed and they can be considerably lighter and thinner than CCFLs so it and weight would not be an issue. Unfortunately I had not counted on the complete abolishment of 20" displays in the 16:10 ratio. Even one year ago I could find a decent selection of monitors in this aspect ratio, but no more. Its encouraging to know that it can be done yourself. Just goes to show how many solutions there are to this mod. Great work!ReplyDelete
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It seems I'm on the right track, I hope I can do well. The result was something I did and was doing to implement it.ReplyDelete
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