iMac G4 20" - and now, something slightly different

[nhaneezy]

hope this mod is allowed here. if it's not please remove post

so after years and years of thinking about this mod, i finally scratched the itch and got started.

the goal of iMac G4 20" using:

mac mini 2009 logic board
original power supply
arduino dome-fan driver
TMDS to HDMI to DisplayPort on mac mini

so i thought of using a mac mini instead of a nuc or other solutions others have used here. that's why i'm not sure if this post is allowed here, but aside from that difference a lot of the electromechanical engineering challenges ARE similar.

why a mac mini? it was nice to not be bothered with the hackintosh aspects of the build. it'll be a genuine mac not hampered by finding parts that are compatible with OS X. it's compatible with El Capitan, so at least i'll be good for updates for the next year. although i oogled over the genius MacTester57's implementation of the startup chime sound, it was really nice to hook up the mac mini's internal speaker wires directly to the original iMac's internal speaker and have it work off the bat.

i'm going to try the same idea with the sleep indicator LED.

i can't think of a way to drive the case fan yet, i don't think there's a way to directly drive one from the mac mini logic board's circuity.

i'm going to keep this thread has a running journal of my work. i was going to wait until i was finished to post a cleaner tutorial but got really excited once i saw the iMac's LCD come up the first time. took my breath away. the only artifact i got is one green pixel in the lower left quadrant. other than that the video is pristine. so i can report that video works fine going through a DVI to DisplayPort cable, into the mac mini or macbook pro

when the mac mini goes to sleep the backlight turns off as well, which gave me relief. system profiler lists it as "iMac Display"



now that the lcd seems to be working, my next step is to tidy up/solidify all the connections. which is just as tedious as performing the TMDS->DVI conversion itself. then, i'll attack the arduino thermistor-controlled fan driver. i was about to go the picaxe route but realized i didn't own a pic programmer. and i thought i'd be a fun time to try arduino programming anyway.

could not have been possible without nights of reading and rereading the work done by MacTester57 and Ersterhernds and dremeljunkies. so i give many many thanks to them

 

[zombillano]

Now I see... You are trying it with a G4, not with a G5 It looks great, which model of mac mini are you using? I'm sure that you are going to make a very good mod, using an original mac will save a lot of time and effort. I can't wait to see how this ends! Also, I'm going to start next week with my project too, It is an 17" iMac G5. I will follow your progress

 

[MacTester57]

Hi nhaneezy

Welcome to the community.

hope this mod is allowed here. if it's not please remove post

Why it shouldn't be allowed? It's good to see a new iMac project here after a long period of inactivity!

could not have been possible without nights of reading and rereading the work done by MacTester57 and Ersterhernds and dremeljunkies. so i give many many thanks to them

Thanks for the praise and the mention!

i'm going to try the same idea with the sleep indicator LED.

...

then, i'll attack the arduino thermistor-controlled fan driver.

I recommend the following for your custom electronics:
- Based on an Arduino Pro Micro. They are very handy and cheap
- A DS 18B20 digital temperature sensor instead of a thermistor
- My current Arduino based SMC solution (based on the work of kiwisinceirth) can be found here: http://www.tonymacx86.com/pcb-templ...management-controller-including-software.html

Good luck!

MacTester

BTW: I'm writing this answer on the HemiMac G4, which is running fine on 10.11.1

 

[megapastore]

Guys, I'm amazed by your work

I'd like to do the same without altering the TMDS cable, so I'd like to get the pinout of the TMDS female connector female. In this case, I can try to build a basic electronic card where you can exit in DVI or HDMI. I need a bit of help with the TMDS connector female's pineout


Thanks in adavance

 

[nhaneezy]

alright after many months of on and off work, i've finally come to a place where i'm ready to stop working on it.

i had to trim a lot of the "exotic" implementations i wanted. these included the sleep light, microphone, ethernet, and pro speaker support.

BUT

i'm happy that i have a functioning iMac G4 20" that runs blazing fast!

i was able to reuse the original iMac antenna by buying adapter cables and plugging them directly into the bluetooth/wifi card on the mac mini logic board. i found the adapter cable on eBay.

i spliced the iMac case speaker with the one on the mac mini and sound came out of them at the same time. which was nice. the mac mini speaker should be kept in place anyway, it looks like it's integral to the fan cooling path.

the same trick worked on the new noctua fan i put in. i was going to use an arduino but i found that soldering the mac mini logic board fan and the noctua case fan together actually worked. it was dumb luck i had no justification to do that. what's awesome now is that the case fan only kicks on whenever the mac mini's fan goes above a certain RPM. and that's exactly what i wanted.

lastly, i just want to echo what a lot of people have mentioned here. the space inside is TIGHT! i thought i had a lot of real estate, given that i was able to fit the entire mac mini inside the optical drive bay. but there actually isn't a lot of space underneath the optical drive bay either.

the reason i haven't been updated for months is that i had two major setbacks. i had everything ready to go and then went to button everything up. and then it wouldn't boot up. something must have shorted somewhere and upon opening it all up again, the power button cable ripped off the mac mini logic board.

the female connector actually lifted off the board. i had to shave some board mask off around that area. just to find a way to solder the power button back on. otherwise i would have been out an entire mac mini logic board. if i wasn't able to do that, i would have scrapped the whole project.

the iMac is now such a joy to use. it's speedier than i thought it would be. a 7 year old mac mini still has a lot of umph to it, especially maxed out to 8gb of ram. el capitan updates with no problem. iCloud, messages, everything works as it should. it's an actual mac inside a mac.

and on a final note i now have a fond appreciation for the hot glue gun.

 

[nhaneezy]

RG178 MMCX Female Straight U.FL IPX Pigtail RF Cable


horrible way to get USB going. i cut up a USB extension cable and barely got the soldering correct. then i said screw it i only need one USB port on this thing anyway


towards the end of the project i found a better way to prop it up so i could work on it. if i had it like this in the beginning it my back would have thanked me more.


oh and the SSD i used wasn't compatible with the mac mini, and i spent two weeks figuring out if i was doing something wrong. i had to revert to using a hybrid ssd/hdd that was compatible. it's not as fast as a pure ssd. but i'll take what i can get at this point.

 

[zombillano]

So... Are you going to stop with this mod? Because it is so cool, Can you do some more detailed pictures? Just to leave more information just in case that somebody else wants to do something like this

 

[nhaneezy]

unfortunately everything already closed up. but I'm happy to answer any questions about the experience i picked up during the build.

the next time i'll open it up is if apple releases an updated mac mini, with a logic board that's hopefully even smaller than the ones currently.

i'll be sure to document a lot more if i ever do that!