Tim Downie wrote:
John Rumm wrote:
Tim Downie wrote:

I am surprised..how long has it been doing it, and how long have you
had it?
Had the sub for 5-6 years now. Hum has slowly been getting worse.
Ah, that does change the probably cause a bit... I would have to go
along with dodgy smoothing cap as well (the time frame would also
possibly coincide with a period when a large number of duff
electrolytics were made, many of which started going tits up after a
couple of years.

Next question, where's a good place to buy replacements?

Before you say "RS" or "MAPLIN", neither of them seem to stock capacitors
with the same spec.

The present ones were made by Licon. 12000 microfarads, 63V. On the other
side they say LSM, 85C(M), VENT.

Terminals seem to be two pins that pass through pcb. (Don't know the spacing
yet). Overall package about 34mm diameter & 46mm high.

How crucial is it to replace like with like? 12,000 seems to be an odd
value. Most catalogues that I've looked at so far list 10,000 & 15,000
microfarad capacitors but not 12,000. Is there any harm in "over-specing"
slightly?

No..none at all.

They are generally -20%+50% anyway.

I HOPE that fixes it..but hum and hum reduction is a black art..I spent
about 6 months tracking down one cause after another on one design..


Tim