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 +

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

If that cap is on the output of a regulator, it is not critical. The
main thing is not to use an electrolytic because of ESR and ESL. Any
value from .01 to .22 should work, and you already know the voltage.

The unit might work with it removed, or it may be noisy, but a 7806 is
a simple passive regulator, there is nothing special about the cap,
only that it must be near the 7806 to keep it from oscillayting. Throw
damnear anything in there. It should work.

This is small stuff, don't sweat it, hopefully this was an isolated
failure and ther is no overload on the 6V line, but of course that
wouldn't blow a cap, so it is likely the thing will be fixed.

I would replace the regulator, not because it might be shorted, 7806s
are rarely fed with more than 12V an it's rare to see a cap of that
type with a lower voltage rating than 50V. However, the cap might have
been shorted and stressed the 7806, so for 44 cents I would replace it
as well.

JURB

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
--
Please remove one 'i' from my address when replying by email.

"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

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

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

On Fri, 24 Aug 2007 17:12:34 GMT, "Arfa Daily"
put finger to keyboard and composed:


wrote in message
oups.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

A 7805/7806 in a TO220 package would be rated at 1A. How long would a
0.1F cap be able to supply such a load, or even a 100mA load?

Then again, maybe the 7806 regulator supplies the bulk of the 6V logic
while a diode-isolated gold cap powers some volatile RAM?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.