Apple Mac mini designed with iPod dock?

She has an IQ of 1001,
She has a jump suit on,
And she's also a telephone...
              ELO, "Time", 1981


I have noticed a missing unpopulated connector on a vertical CD/HDD interconnect board. There are also a few components that were left out during assembly. There is surprisingly big (by mini standards) empty space around that area inside the mini case.

Connector has a full Firewire bus and extra control signals on it. What could it be? Integrated iPod dock at the top of Mac mini case? Interface to some other external device? Missing internal module? Extra row of external connectors on the back?

And most of all, has it been abandoned at the last minute or still being developed? Or is it waiting for its device to become ready?

Here it is in its full glory...

Starting from the left...

Missing resistor R1 and LED DS1 make drives access indication circuit. Like the one each PC has on its front panel. If installed, LED will light up on access to hard or optical drive. R1 value should be somewhere around 500 Ohms.

C3 is a decoupling capacitor for the Firewire supply voltage to external devices. Any small SMD tantalum rated at 20V or more will do. Positive terminal is up. F1 is a normal or polyswitch fuse rated at half an amp or so. D1 is just a high current diode, anode is on the right. C3, F1 and D1 together provide +18V supply to Firewire bus on connector J7.

D2 is a diode (anode is on the right) that provides +18V power back to the logic board (pins 89, 91 of edge connector J6). Since it is missing I assume certain part of the logic board schematic is not powered at the moment.

Actually, this D1 diode confuses me. It is there to stop the current provided by another Firewire device on the same bus from flowing back into mini. Imagine two Macs connected together with a Firewire cable. If the second Mac has higher Firewire power (specification allows up to 30V), D1 would stop that voltage from reaching inside the mini and frying its power supply together with half of the logic board.

It looks much like this circuit was designed for a standard 6-pin Firewire socket... Do I contradict myself now? Maybe...

J7 connector pinout

1 (rightmost) Edge connector J6 pin 90 Firewire TPB1-
2J6 pin 86Firewire TPB1+
3, 4Ground
5J6 pin 98???
6J6 pin 100???
7J6 pin 97???
8J6 pin 99???
9, 10Ground
11J6 pin 82Firewire TPA1-
12J6 pin 78Firewire TPA1+
13, 14, 15F1, C3Firewire +18V power
16Ground
17J6 pin 56???
18J6 pin 52???
19, 20J6 pins 63, 67, 71+5V

I would guess most useful project is to use Firewire connection. Data lines are already fully wired but you need to retrofit at least F1 and D1 to get the power for a full 6-pin Firewire socket.

This is the logic board part with clearly visible FW802B Firewire controller connections to J6 edge connector socket.


© Leo Bodnar, originally published 5th February 2005. Home