wrote in message
ups.com...
On Aug 24, 4:11 am, "Arfa Daily" wrote:
I'm pretty sure that I did see a rectangular one once, but whatever, if
it
is 0.1F at 5.5v, it is *not* just any old cap put there to stop the
regulator oscillating - it is definitely a goldcap for backup.

Yes - the output stability cap would be something like a 0.1uF
ceramic.

Are you sure that there is not a diode between the regulator's output,
and the cap?

Hmm, I thought it was a direct connection (via jumper), but I'll
double
check that. There is a "+5V" silkscreen label in that general area,
which
brings up another possibility - perhaps that regulator is supposed to
be
a 7805. I'm working on getting the schematic, that should clear
things up.

TM


I guess it will. I have seen 7806's used with a diode and goldcap. The diode
drops the rail to around 5.3v, and also ensures that there is no reverse
leakage path from the backup cap through the regulator to ground. Most
system control micros are quite happy with a rail of just over 5v, and lots
of hifis have got such a voltage on the 'nominal' 5v rail.

Arfa