[Ham-Mac] pinout guide for iMac.

[Matthew Schiller]

As I think someone else mentioned... That chip is an i2c serial eeprom 
(if memory serves).  It's most definitely NOT the power amp.  The 
speaker puts out way too much humph for a power amp to not have some 
substantial connections to power/gnd, not to mention have a heat sink!. 
  If you do some examination of the main board you'll find the power amp 
in with other Audio circuitry.   I believe they did this, because the 
speaker outputs have potentially dangerous current capability, plus the 
connector used as the potential to short the speaker output to ground.  
Shoot if my memory was better I'd know for sure, while I didn't design 
the circuit I entered into the schematic capture program myself!  With 
the i2c rom the mac can detect if the proper thing is plugged in and 
not feed too much power to headphone, for example.  (granted someone 
would have to be pretty silly to rig up the appropriate adapter!)

-- Matthew Schiller
KD6BWE
Previous Apple Intern (15" iMac Main Logic Board hardware team)


On Tuesday, January 27, 2004, at 01:44 PM, David Anderson wrote:

> Hi again Louis,
> 			Well well, very interesting indeed, I knew that the USB powered 
> speakers with the Cube had an external amp, but did not think that the 
> new iMac speakers had! - I assumed (wrongly) that the small plastic 
> interconnect was just that a purely passive connector
>
> Why on earth did they do that? - Wouldn't it have much simpler to have 
> the amp inside the Mac? - Anyway, wonder why you need the connections 
> for the speaker socket? - Does the headphone socket not do what you 
> want? - For interfacing to a radio?
>
>
> On 27 Jan 2004, at 8:51 pm, Louis C Bruckner wrote:
>
>> David,
>> I will beg to differ.
>> I had a set of apple pro speakers to go bad 2 months after I bought 
>> my iMac and apple replaced them and did not want the old ones back.
>> I am sorry that I did not do further reverse engineering but I did 
>> find a chip located in the round plastic housing that interconnects 
>> the left and right speakers to the 4 conductor 1/8 in connector that 
>> has a metal shroud.
>>
>>
>
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