After several years with the same physical setup, I have a new hum in my
systm. I have a dual monitor PC with LCD screens placed between a pair of
Tannoys. The Tannoys are driven by the CRM outs on a Soundcraft Ghost.
The system has been very quiet. Last Friday, as I was powering up the
system for a Nuendo mix session, I had a hard drive problem. After
repairing the PC, and finally getting everything going on Saturday, I have
a hum.

The hum only occurs when 1) The LCD's are on and receiving a signal from
the PC and 2) when Bus A is being sent to the Tannoys. If I turn off the
LCD's (or the PC) the hum goes away. If I switch to bus b, 2trk A or 2trk
B, there's no hum. All of the tape ins/outs/inserts go to a patch bay,
where it's lined up with a pair of Tascam 24 tracks. I first brought the
bus A gain all the way down, with no effect, then I panned every channel
left, with no effect (hum is from both speakers), I then pulled every cable
except power and speaker cables from the Ghost with no effect.

So it seems that my bus A got screwed somehow. My Question is: is there
anything I can pull apart and look at? I am not an electronics wiz - I can
solder my own cables (and do). I'd rather not take the time (and money) to
get it to the local repair shop, and if I did, I don't know that the
problem would be reproducible without sticking the same PC in place.

With low expectations, but still hoping,
Greg