Postby ClubAndCountry » 07 Dec 2009, 08:31
If there's *any* question whatever that the fan isn't working right, stop using the amp and replace it. If it sticks, the amp is toast. Best of all, replace the fan and then sell the amp before anything else bad happens. Apologies if this doesn't go down well with anyone who owns one, or any colleagues of SteveD's who may have been responsible for designing it. It's just my opinion, but I will not work on these amps any more because I cannot guarantee they won't fail and I don't want to be the last to have been inside.
Regardless of what it sounds like (which personally I don't care for either), the Mode 4 is a failure waiting to happen. The power section is nothing more than four Valvestate AVT series/MG series IC power modules. I've seen so many failed ones of these I've lost count... and two Mode 4s so far with burned out ones. (Or perhaps incinerated is a better word.) Regardless of their supposed built-in thermal and short-circuit protection, IC power modules like this are just not as reliable as discrete-component power sections in real-world use. Sadly they are becoming pretty much standard in most cheaper solid-state amps.
The whole amp is just a glorified Valvestate really - with four times as many of the parts that most often fail in the ordinary Valvestate models. And I actually quite *like* Valvestates for what they are, and what they cost - but they are not quite professional quality amps either in tone or reliability. I would not personally own any amp with this sort of power stage design, especially not one that relies on effective fan cooling.