iMac G4 20in NUC mod - CelestialTower

Hi, I know theres a few of theses here on the site but I've had this iMac for months and now that my university is out I finally have time to do this!

This mod is INCOMPLETE however I've made progress and I'm waiting on one more part to come in (12v to 24v dc-dc step up) it should be here tomorrow, so ill be able to test the display without the original PSU.

I've got my personal blog where the most up to date information is/will be:

http://celestialtower.com/Site/iMac.html

I plan on "tutorializing" further sections better but it's a start right?

I also have noticed other people are doing this same mod right now So I figured we should help each other out, I was going to mention how to get dremeljunkie's (http://www.dremeljunkie.com) old images by using thewaybackmachine but a more diligent person beat me to it.

My goals: (copied from my blog)

The goal of this projects is rather simple (not really): Modify this 10+ year old computer with modern components while retaining full functionality/design.

So heres what I want:
Native Power Button
Native Power Supply
Native LCD
Native Microphone (Built in)
Apple Pro Speakers (Modded for 3.5mm jack)
DVD Drive (this is something many tend to leave out, purely for aesthetics I’d like one)
Native Display Light
Some stuff I may or may not do:
Apple chime on boot
Brightness control via buttons on the back (or interfaced with a separate input device that would plug into a port on the back???)
Internal Speaker
Hard drive just a cheap 500gb 2.5in SATA HDD(5400rpm for reduced heat) (This is something ill do if the systems proves useful)

On the form @InsaneCultist is working on his right now and @ersterhernd did a successful one but he had to downgrade to a HD 4000 graphics based NUC due to graphical issues. I want to thank ersterhernd because he potentially saved me money. I am curious if an HD 4400 NUC would solve the problem, I really want the native SATA port and USB3 but I don't really need them...
Regardless as soon as the screen is confirmed working I'm buying an NUC. Hopefully my tutorial doesn't suck too much,
Thank you!

Awesome! Another 20" G4 on the forum!

Good luck with it. Will watch your progress. My 20" is still working flawlessly, btw...


Regards
Ersterhernd

I read your whole thread back when you first wrote it, That really must have been frustrating with the graphical issues! Sorry about that...But thank you you and dremel junkie really inspired me to take on this project! I have been researching if perhaps the HD 4400 wouldn't have the graphical issues you unfortunately had, but it looks like they are based off the same architecture (see image). But then I remembered something (recently) when apple switched to the mini-display port connecter/thunderbolt for display output I bought a Mini-Display to DVI adapter and when used with a DVI cable to my monitor it worked flawlessly but when I put a "third" adapter in the middle (DVI-HDMI) I got graphical glitches on the screen like crazy. So i figured your config failed because you had (from what I understood) it like this: iMac wires--->DVI--->HDMI--->Mini HDMI. I figured a DVI to Mini HDMI connecter might solve the issue Link: (http://www.amazon.com/Accell-J132B-004B-Type-C-Female-Adapter/dp/B0098HVY0Q/ref=sr_1_2?ie=UTF8&qid=1401328935&sr=8-2&keywords=dvi+to+mini+hdmi) I know it's a stretch but then @InsaneCultist here on the forum had the same idea so I hope it works out for him, I'm glad to know I might be on to something since someone else thought the same thing.

Once again thank you! I never would have guessed the HD 5000 would cause trouble like that. I'm fine with Hd 4000 graphics I just really wanted that SATA port/USB 3 combo (no thunderbolt).

LCD Test Problems:

I think I have everything hooked up correctly (double checked)
I'm using the molex 12v to 24v method to test the LCD and I got the back light working(I think; it stays black but the whole screen lights up)
But with anything connected to the DVI end I get a white flicker in the middle of the screen as if the image almost was there then the display goes black again but stays lit like before.

Anyone have any ideas I wasted a day on this and got nowhere... I disconnected EVERYTHING twice and reconnected to be sure

I can post pictures tomorrow I've been up till 4 am so maybe a fresh look tomorrow would help. Any advice is appreciated!

Update:

Ok the "Hot Plug" detection works but the screen still stays black while the computer recognizes the screen as "iMac" with all the correct resolutions. So did I kill the inverter and if so how; i was careful to never leave the screen on for more than a few seconds during testing could it still have died? I've got an extra screen (yes I got a 20in iMac g4 screen with a few dead pixels just in case but not the whole computer) that I could steal the inverter from but I'm not sure... Here's a video of the momentary white flash I get with me connecting it to two different computers one with intel iris (macbook pro) and my old Hp hack with hd 3000 (probook 4530S):

http://youtu.be/BX10voSkHfc

It improved quite a bit with my Macbook; have no idea why


And a few picture's of the (messy) wiring,DVI connector (got a relatively clear one!), and a close up inside the dome:



For now ill reconnect everything to the DVI connector (again) because I checked the voltage that my up converter was throwing (23.5) this should be fine besides my multimeter isn't very accurate anyway...

Some of the pins connecting to the DVI plug aren't straight so that might have something to do with it...

So any advice please?

Sounds like you may have a ground that isn't solid. Try connecting any grounds directly without alligator clips. Mactester suggested this fix recently and it worked.

Probably worth a try.


Good Luck.

E and MacTester recommended to me that the shielding on the TMDS wiring be wired to the Ground on the DVI connector. I did this before I tested the display, but I would go ahead and add that in to see if it makes a difference.

-IC

I tried this right after you suggested it:

Only problem it won't let my power brick turn back on until I removed it (I used an alligator clip) It worked the first time but upon a second power on/off my brick looked like it died. The first time made no difference anyway still no picture

So confused I think I have it perfect... I have to directly connect 1 more of the ground wires. I've done all but the inverter ones mostly because they won't easily reach...oh well I'll try that now.

Thanks anyway!

Edit: I wasn't clear the brick and screen is fine it just won't work with that grounded. Worded that bad; sorry.

I directly twisted the ground's for everything but the two inverter grounds; but i used separate alligator wires for them and connected both to a spare wire that tied around the up converter ground; all other grounds have been directly tied around their own molex ground except the extra wire from the hot plug switch it has to share a ground with something else. I do have the extra inverter but I'm apprehensive to use it because it could die too...hmm...just don't know there was no smell/smoke; but it seems IC had the same issue and somehow worked it out. (http://www.tonymacx86.com/imac-mods/130689-ics-20-imac-nuc-flowerpot-2.html) No image, with backlight, etc.

I'll just straighten all the DVI pins and separate them with electrical tape before I mess with the inverter. I'll update later.

UPDATE:

I cut the amount of alligator wires used in half and all but the inverter wires are grounded without them. It has made no difference it behaves the same...I doubt the inverter's dead at this point; but I'm at a total loss of what to do...any other trouble shooting steps? I'm using some 20 AWG spare wire in-between some points because the wiring was too thin/difficult to handle and thanks to this the hot plug detection worked. I also stole wires from my 15 in iMac G4 (if that helps).

I know what it can't be:


It can't be my DVI pins I've redone it three times and at this point I know it's fine.

It can't be the step up converter; I used a muiltmeter it was around 23.5 volts.

It can't be my hot plug section implementation because that works fine, OSX see's the screen just fine (windows 7 too).

What it could be:


The inverter; not sure how but it's a guess.

My AC-DC power supply (ill post a picture it has a 12v and a 5v rail and I used the molex splitter as Jberg suggested)

I used an adjustable wire stripper on the inverter cables and I think the result's aren't perfect but It shouldn't matter because there aren't signal wires (right?) but I'll order a stripper to handle to wires to be sure...

The inverter grounds? I guess the alligator wires could cause a problem but I can't twist a wire around them to directly ground them with the step up because they are too short and ill need to strip more which I won't do until the correct wire stripper arrives. But i don't think this is the case.

What I've tried:

Re did the pin out on the DVI connector (3 times)

Re wired everything 3 times (now with half the alligator clips)

Grounded the DVI to the cable shielding (got it to work) thank you IC

Used a DVI to HDMI to plug into my Macbook pro (intel Iris), Probook hack (HD 3000) the display is seen just fine and the backlight is on and the screen flashes but no image

Used a DVI to DVI to plug directly into my Desktop hack (dual boot's windows 7) Same result as above

I've attached the pictures below; Im cleaning up and giving up until I can get a friend of mine to help me out (perhaps tomorrow?)and until I get the smaller wire stripper so I can better strip the inverter cables and not waste anymore wire using my cheap adjustable one. I tried a jumped ATX power supply as well and it made no difference.

I know this is a long post so I thank anyone that took the time to read it;