"Franc Zabkar" wrote in message
...
On Thu, 23 Aug 2007 21:04:08 -0700, put finger to
keyboard and composed:

At site C401 of main board. Cap is some kind of polymer electrolytic,
but rectangular, not cylindrical. Roughly 9/16"H x 1/2"W x 1/4"D,
black plastic case,
with flat sheets of polymer/plastic inside. Markings as follows:

S 5.5V
0.1F
- 6A +

0.1F 5.5V sounds like a "gold" cap. These are normally used for
backup. I've never seen a rectangular one, though.

This is on the output of a 7806 regulator (IC401). Cap was cracked,
regulator ran warm but works out of circuit. Did Denon actually intend
to use a 5.5V cap on a 6V rail, or is this an incorrect substitution?
Solder joints on cap appear to be factory, but the silkscreen for this
part is round.

Thanks,
Tony

- Franc Zabkar

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. Are you sure
that there is not a diode between the regulator's output, and the cap? And a
7806 is not 'passive'. The 78 series regs are very much active shunt types,
containing a feedback controlled regulator drive circuit, that maintains
very close tolerance on the output voltage, and provides significant ripple
rejection of the order of 80dB as I recall. They also contain circuitry to
protect against shorts, providing voltage foldback in the event of an excess
current condition, and thermal shutdown for excess temperature conditions.

Arfa