[g]

On Jul 23, 12:02*pm, jamesgangnc wrote:
On Jul 23, 9:42*am, jamesgangnc wrote:



My adcom 535 II has started exhibiting hum and scratchy noise. *I
isolated it from my other components and it still does the same the
with nothing connected. *It's doing it on both channels but one
channel is a bit worse that the other. *Which is a bit annoying since
the amp is two independent amps in one box. I'm suspecting the
electrolytics in the power supplies. *When I play around with them it
affects the scratchiness. *I don't have a schematic for this amp but
it looks like the power supplies are basic unregulated rectifier/
capacitor arrangements.

I'm thinking I should replace all 4 electrolytics. *I was browsing the
newark selection and it looks like I could raise the size a bit and
still fit in the space. *The original ones are 6800uf at 63v. *There
are a number of 8200uf that will fit. *The lead spacing is a bit of a
chore since the originals are a lot wider that today's typical 10 or
12mm.

Any suggestions on my diagnosis or on bumping up the size?

My scope shows a noticable sawtooth at 60hz on the power supply
output. *Looks like there are a some .22 film capacitors on the power
supply board as well. *I would think they would be filtering out the
scrathchy/static sort of noise I'm getting. *I suppose it's possible
that the power supply caps explain my hum while the static sort of
noise is a different problem. *There are several small electrolytics
on the amp boards as well. *Anyone got a schematic for one of these
amps they could share?

I guess it would be easier to use rec.audio.tech
Its hard to believe the caps would not filter with no signal input.
I would first check all connections including crimps.
I don't like crimps.

greg