I have dealt with this problem on several occasions. Not with pro audio equipment, but with pro lighting gear. Virtually all halogen and arc-bulb club lights have very high CFM fans blowing directly on to the bulb and PCB. I use haze (atomized glycol, a physical reaction, much smaller particles) and not fog (thermal reaction, comparatively huge particles). In my utterly non-scientific experience, extended exposure to haze does less damage to equipment than a similar exposure to fog. That said, I have a small graveyard of blinkenlights that no longer function because of PCB issues. I'm really liking my new LED fixtures which generate almost no heat and don't use fans. </utterly off topic>