13 Feb
2008
13 Feb
'08
1:03 p.m.
On 13 February 2008 at 12:45, Joe Hartley <jh(a)brainiac.com> wrote:
kc> Could you share with us the symptom and specifics of the solution
kc> involving replacing a cap? I'm wondering if the noisy channels
kc> problem mentioned here a couple of times is related somehow.
Heh - I just Googled to see if I could find a good link to describe
the process and the first link I come up with is a post of mine to the
Planet CCRMA list about the problem!
My symptom was a horrendous buzz on all 8 output channels.
One unit I had started having troubles with buzz on the output
channels a few months after I bought it. At first power cycling the
unit would get it to behave, and at first it was only a few channels.
Eventually it was all channels, and I couldn't get it to behave.
I returned the unit under warranty and got a replacement.
When I took
apart the breakout box, I saw a quadrupling circuit on the left hand side
of the bottom board (toward the front of the case, underneath the small
board that's on top) that had a couple of oozing caps.
That happens more often in electronic equipment than the public generally knows.
Remember the laptop battery recall from months ago? I've seen quite
a few recalls for capacitor problems over the last 3 decades of
working in the electronics industry, first as a part-time soldering
and assembly person, and now as an analog IC designer.
I replaced them with 2200uF 35v caps from DigiKey:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=493-1879-ND
If you've ever done electronic soldering before, it's a trivial procedure:
remove the 2 small 2200uF 25v caps and squeeze the larger caps in there.
Doesn't sound too bad.
The 35v caps are recommended, it was the
underspec'ing of the caps that was
causing the problems in the first place.
Did you measure the voltage somehow, or did you get documentation
from M-Audio somehow to figure out the new recommended voltage rating?
Excellent write-up. Thanks a bunch!
--
Kevin