Re: I'm a newbie all over again..!

[rubywand@aol.com (RUBYWAND)]

In article <284391564wnr@klatch.demon.co.uk>, John Le Febvre
<John@klatch.demon.co.uk> writes:

>Somebody else pointed out that it was probably a patch to improve the
>sound output of the board and reduce noise.
>I will get more info tonight and post for future reference.
>
>

    This seems to be the correct answer. Just a couple nights ago I was
doing some work on our ROM-01 motherboard and noticed the 1-transistor
mini-board. On the underside of the motherboard, beneath the boardlette, a
surface-mounted resistor (SR1) has been scratched out. Leads from the
mini-board run to SR1's connection points as well as Ground and a +12V
supply point near Op Amp UM12.

    The circuit on the mini-board is a low-gain 1-transistor amplifier
which seems intended mainly as a buffer/voltage-level shifter between the
'old Apple' sound output of the Mega Chip and Op Amps which drive the
Speaker and Sound jack.

    By the way, the circuit was certainly installed at the time of
manufacture and was not part of the standard ROM-00 to ROM-01 upgrade. (I
was present during an upgrade. It took just a few minutes and no boards
were soldered on.)