Yamaha EMX660 Mixer (Limiter light stays on, no output to speakers)

[ifeelfine]

Greetings! My Yamaha EMX660 mixer's limiter light indicator (the one on the power amp 1 side) is on full-time at power up and I have NO output to my speakers.
The unit powers up as normal and the fan still works. My mixer was returned to me with this problem after loaning it to a friend, who loaned it to another with my permission. So, I have no idea of the circumstances that caused this problem, and both "friends" plead ignorance. My guess is that someone in their band didn't know what the hell they were doing and plugged something into my mixer when they shouldn't have, or where they shouldn't have, or just plain didn't follow PA system 101 causing too much of an overload on the mixer.

The owner's manual only describes the purpose of the limiter indicator and the troubleshooting section doesn't cover this particular problem. I checked for output to my speakers in the main-main, main-monitor, and bridge configurations (turning the mixer off before switching positions of course) and the problem remains. I took the unit apart to visually inspect all circuit boards and their components, fuses, and traces for signs of being blown, burnt, arcing, etc ... and everything looks fine ... as far as I could see with the naked eye and a flashlight.

Internet searches revealed that I more than likely have a blown power amplifier. Is there a quick and easy way for me to isolate this problem to being a blown power amplifier? If this is the case, can anyone tell me approximately how much it would cost to have an electronics technician replace it for me (part & labor charge). Thank you kindly!

[Enzo]

I'd agree, a blown output is most likely. And I'll add, it may not be your friends' fault at all. Circuits fail for many reasons, and if anything ever failed when you were using it, was it always because you used it wrong? The output of a channel could have been weakened by a momentary connection problem or faulty cord MONTHS ago, and is just now getting around to finally croaking. Oh yes, they could have screwed it up, yes.


The unit is stuck in protect mode. The way to determine this is to go inside and look for unwanted DC voltage on the output circuits prior to speaker relays.

There is no replace, there is repair Repair includes replacing bad parts, but also adjusting whatever needs it and repairing damage to the copper on the circuit board. Very hard to say what all is damaged inside, so difficult to estimate, at least without seeing the unit. In my shop, that would cost you a minimum of one hour labor at $60. And probably not over $200. Shop rates vary.

[ifeelfine]

Yamaha EMX 660 Mixer

Thank you for your reply Enzo!

[scootscoot1112]

Hello, I know its been a while sense this thread has been active but I was wondering if you ever fixed your emx660? I seem to be having the same problem. The whole front side of my board is working but I cant get any signal out the back power amp side. I checked the basics and its nothing obvious so I was hoping you might be able to help me out, thanks.

[ifeelfine]

scootscoot1112: I did get this fixed, but had to take it to a certified Yamaha electronics technician and paid about $165 to have it repaired. Unfortunately, I don't recall
what components were replaced and I no longer have the receipt with the description of repairs. I'm pretty sure it was a couple of diodes and maybe a resistor or 2 that were replaced. Inexpensive components but the main cost involved were in the disassembly, reassembly, troubleshooting, and testing of the unit ... as was expected. It's been working fine since then. Sorry I can't be more explicit in what exactly was replaced, I just don't remember.