MacTester57's HemiMac G4

[ersterhernd]

Yes I already tried that, MacTester. It was of no success.

I'm curious to see how you're going to implement the 2.5mm jack, and where the power for it is going to come from. If history repeats itself, I'm certain it'll be another 'Engineered by MacTester57' solution! On another note, this replacement LCD I received had a small scratch on it upon arrival. Have you ever tried to remove an LCD scratch? I've read about toothpaste, turtle wax etc, but so far have just used a little vaseline to camoflouge it. Don't want to add insult to injury by making it any worse.


Ersterhernd

 

[MacTester57]

Yes I already tried that, MacTester. It was of no success.

It could be USB related. Did you try to disconnect all not needed USB devices?

I'm curious to see how you're going to implement the 2.5mm jack, and where the power for it is going to come from. If history repeats itself, I'm certain it'll be another 'Engineered by MacTester57' solution!

Here it is. The (probably) first iMac Hackintosh with original Pro Speakers, connected via the proprietary 6-pin 2.5mm connector. The two pins for the locking chip inside the speakers were left floating.

Here you can see, how the wires from the speaker output on the amp are connected to the original connector:

This is the amp, which I've used: Link

The speakers, connected to the rest of the cut motherboard:

Everything hooked up and working. Note the "genuine" Apple box of the used USB audio device: Link

And a short video:

On another note, this replacement LCD I received had a small scratch on it upon arrival. Have you ever tried to remove an LCD scratch? I've read about toothpaste, turtle wax etc, but so far have just used a little vaseline to camoflouge it. Don't want to add insult to injury by making it any worse.

Vaseline is OK. Did it too.

MacTester

 

[ersterhernd]

Ahhhhh, THAT'S how you did it...

Essentially, a USB audio device similar to what I used, then piped out through a small USB amp routed through the 2.5mm plug. Ingenious, MacTester. I really like the internal amp idea. I've ordered a couple to have on hand for later projects. Dirt cheap, so why not...

I routed my audio out of the system through a 3.5mm jack and then into a 20W external amp which is screwed to the underside of my computer desk, so it's completely out of sight. Looking at the iMac, you only see the dome/screen and the two speakers. It'll make the speakers shake in their boots if I crank it too high, so I set it to the maximum 'safe' volume and do all volume adjustment thru OSX.

Great work on your project so far. I look forward to see how you wire your ethernet jack. I did both of my iMacs manually, wire by wire, and thankfully they both work excellent.


Ersterhernd

 

[MacTester57]

I think, that I've just found a potential issue with the original USB ports. The 5V and GND of all three ports are bridged. I guess, that this will not work, because each port needs its own 5V from the USB controller.

What do you think?

Today, I've removed both FireWire ports, which will be replaced with a USB 3.0 port.

MacTester

 

[ersterhernd]

I think, that I've just found a potential issue with the original USB ports. The 5V and GND of all three ports are bridged. I guess, that this will not work, because each port needs its own 5V from the USB controller.

What do you think?

Today, I've removed both FireWire ports, which will be replaced with a USB 3.0 port.

MacTester

Bridged??? Now maybe I know why I couldn't get a consistent result when I had mine soldered. It was fresh in my mind how your USB header got burnt by that Bluetooth module, so I gave up on the idea of re-using the ports. I never even thought to check resistance between the three ports. Can you cut the traces on the board to separate the ports? It would sure be nice to see you keep them. Just don't burn that NUC, it's not worth it.

My initial test results after wiring it up were all over the map. Now I know why.


Ersterhernd

 

[kiwisincebirth]

I think, that I've just found a potential issue with the original USB ports. The 5V and GND of all three ports are bridged. I guess, that this will not work, because each port needs its own 5V from the USB controller.

What do you think?

When I installed the four additional USB ports in my Self Build, I only wired the data pins D+ D- from the header sockets on the DB77KB motherboard. Ground and +5V came from the SATA power cable, and was wired (bridged) to all four USB sockets. So far I have not had an issue running several devices of these ports, although I haven't extensively tested it with multiple high current draw devices

http://www.tonymacx86.com/others/90651-g4-cube-inspired-self-build-4.html#post58784

To my knowledge the +5V USB line on a USB port doesn't have any active current monitoring, just simple current limiting, to prevent damage if short circuited. Current draw is reported (in System Information) from the USB data signalling, the same signalling that reports product and vendor ID's

If in your situation I would proceed (with caution), and:
1. Wire the data D- D+ from the USB ports to the G4 motherboard pins,
2. If feasible get a 5V supply voltage from pico PSU (or similar) to the USB bridged 5V pins.
3. Wire a common ground to the G4 motherboard.

The issue with the above is ensuring that the USB (and other) connector on the G4 motherboard are isolated from other components on that motherboard. It may be a simple as cutting traces to the USB data pins on the sockets to get isolation.

But a shared ground (or 5V) plane, quite often in a layer inside the motherboard, would be very difficult to separate.

For this I would strip all the components off the motherboard, thus removing any active/passive circuitry to that ground, except for the connectors you actually intend to use. Thus the ground would be truly be shared across all these connectors.

Of course a visual inspection, and a continuity checker to ensure appropriate continuity, and no shorts would be essential.

Just my 5c
Kiwi

 

[MacTester57]

Ersterhernd, Kiwi,

Thanks for reply. I'm not yet sure how I will do the USB wiring.

The next step will be the implementation oft the following functions on one single PCB:
-ON / OFF control of the Pico PSU in accordance with the NUC state
-PWM control of the "breathing" sleep LED
-Triggering the "Apple Chime" startup sound (only during boot, not during rewake from sleep)

The software tests on the bread board are finished and here is the first PCB layout concept. Its size will be about 45 x 26mm:

MacTester

 

[kiwisincebirth]

Ersterhernd, Kiwi,

Thanks for reply. I'm not yet sure how I will do the USB wiring.

The next step will be the implementation oft the following functions on one single PCB:
-ON / OFF control of the Pico PSU in accordance with the NUC state
-PWM control of the "breathing" sleep LED
-Triggering the "Apple Chime" startup sound (only during boot, not during rewake from sleep)

The software tests on the bread board are finished and here is the first PCB layout concept. Its size will be about 45 x 26mm

MacTester

If you want to reduce the size of the board slightly, you could move the bottom transistor (and base resistor) to the left and up one row.

Additionally have you considered combining the LCD brightness function into a single board with larger 14 pin pickaxe processor?

Kiwi

 

[ersterhernd]

Hi MacTester, you probably already know this, but if you have an unused 5v USB pin perhaps where your a1181 Bluetooth will connect, the USB power stays on during sleep and remains off when 5vsb is on the pico when the system is off.

Perhaps this pin (if you have it) could be used, too?

Just a thought. Your layout grid looks great.


Ersterhernd

 

[MacTester57]

If you want to reduce the size of the board slightly, you could move the bottom transistor (and base resistor) to the left and up one row.

Yes, you are right but the layout with both transistors in one row looks better in my eyes.

Additionally have you considered combining the LCD brightness function into a single board with larger 14 pin pickaxe processor?

For a new project, I would try that. However, I've already invested a lot of time in the current program(s), the brightness controller is already finalized and mounted (completely invisible) behind the PSU. Another issue is the limited multitasking ability of the Picaxe controller, if its PWM functionality is used.

Hi MacTester, you probably already know this, but if you have an unused 5v USB pin perhaps where your a1181 Bluetooth will connect, the USB power stays on during sleep and remains off when 5vsb is on the pico when the system is off.

Yes, I know. I don't want to "waste" an USB port and I think, that the current solution is better.

MacTester