Date: Fri, 8 Sep 2006 22:41:09 -0400
From: "Teo Zenios" <teoz at neo.rr.com>
My latest acquisition came in today, a Mac IIci, that I
wanted to
use as an OS 6.08 machine
with a Daystar Turbo 040 (68040/33) accelerator. Anyway after
cleaning up the system and
I took the card out and notice there was a capacitor
missing on the
back with a nasty looking
black burn mark. So I started looking around inside for the burn
metal part and notice I did not
smell or see smoke or little capacitor parts (its a surface mount
with no numbers on it)
So what I want to know is how the thing functioned at
all without
the cap (burnt carbon acted
as a capacitor in some way)? and what caused it to stop working.
It looks as if that cap (C54) ties the upper righthand pin of the
oscillator, which I think is pin 14 or Vdd.
As someone else wrote, it is probably just a decoupling cap, but it
may be hard to tell for certain as I believe that the Daystar boards
have more than four layers, which means that there are traces we
cannot view.
If anybody have an original Daystar Turbo 040 33Mhz
card with the
cache on a separate board
could you let me know (if possible) what value C54 s supposed to
be? The cap looks to be tied
into one or two legs of the oscillator chip that controls the CPU
(Ecliptek EC1100 16.667Mhz
93-10).
There are no markings on C54. It looks just like the two caps next
to (below) it, but there are no characters which would betray a
value. I don't have a capacitance meter.
Jeff Walther