Originally Posted by RDKing2
Lost a channel on my 14k last night, the mute and tem lights are lit on the B channel. Found two blown fuses on one of the channel boards. Replaced them and they just blow again. Poking around in the amp with my mutlimeter it appears there might be a short somewhere. The clicking is a relay on a board that the power cable connects to right after entering the chassis. While I know how circuits work I am not sure what all the components do so diagnosis is going to be tough for me. Any pointers on where to start would be great if someone can help. TIA
The mute lights indicate a short, which usually happens after component failure. Component failure can be the result of an upstream problem or just a faulty part that went kaboom.
The main concern with 14,000 watt amplifiers is heat. Even at 92% efficiency there is still the potential for over 1,000W to be lost as heat. When you cram all of that into 2RU, you exasperate the situation. These amps have to be kept cool. Modding the fans is the 1st place I would look if there is a component failure that leads to a blown fuse. Personally, I wouldn't mod the fans without making sure there is a minimum of air flow with any mod being considered.
Another consideration is switching the amps to 120V operation. I've used 30A home runs and many of these high powered switching amps can't handle the current. So, if you list you particulars (what operation mode, speaker load, A/C supply, speaker wire length, gauge, what source were you playing at the time of the failure or the last previous listening session and at what level was the playback, or the level indicator LEDs, etc.) it'll be easier to get at the source of the problem.
I would also add that you need to check the transistors (the 3 prong components connected to the copper heat sinks) on the faulted board. Usually, if it gets as far as the fuses popping, all of those transistors will be shot, as well as other components. If so, the best fix is to order a new channel board and just replace it.
Finally, IMO, if the temp lights came on as well as the mute lights, I would check the fan switch (that's just what I call it) Triac on the under side of the board. It's attached with a 1/4" diameter black button that looks to be melted on the other side, like a plastic rivet. If it was heat that caused the initial problem, sometimes that triac will fail and your fans won't kick up in speed to fix the heat problem (this will always happen if your fans are not sized and spec'd to the task, as in a modded fan situation). If it failed, you'll see it blown out and probably see bare metal in the center exposed from the blowout.
Because there are some seriously crazy people pushing subwoofers to incredible lengths, there is always the question of abuse. These amps give a lot but that doesn't mean they can't be operated into an early grave. I don't agree with fan modding these amps. If the fan noise is too much, either move the amp to a separate location or buy a lesser amp with self noise that suits you. To repeat, they MUST be kept COOL. That's why they were designed with copper radiators and 4 fans.
If it wasn't heat, then it might be too much current. If it wasn't too much current, I would suspect a faulty component. Listing the particulars in your specific case, as I mentioned above, will help track down the original problem.