Smoked! - Contractor Talk - Professional Construction and Remodeling Forum

Inner10 · 05-12-2009, 11:20 PM

I had a PA amp catch fire today, brand new after 20 minutes of operation an output transistor smoked popped and ignited, flames came through the vents by an inch...

Until now I've never seen such a thing, I've had caps blow, speakers ignite but never an amp; anyone ever seen this?

Apparently the amp was designed to protect the fuse lol.

Tinstaafl · 05-13-2009, 06:05 AM

Quote:

Originally Posted by Inner10

IUntil now I've never seen such a thing, I've had caps blow, speakers ignite but never an amp; anyone ever seen this?

I was an electronics tech for quite a few years; I've seen it happen to amps, radio transmitters and TVs--though in every case, the fire died out pretty quickly from lack of real fuel to feed on. Definitely a wakeup call!

Fuses are insurance, but no guarantee. Particularly if the driver/final is handling a fair amount of power, it's quite possible for it to fail in such a way that it develops a really hot spot without exceeding the unit's total rated current.

hbiss · 05-13-2009, 01:16 PM

Care to tell us who the amp was made by and which one? Just as a heads up to watch out. Awhile back I remember some QSC amps had a similar problem.

-Hal

Inner10 · 05-13-2009, 11:10 PM

Atlas AA 120, I've installed dozens of them without problems...I've had lots of amps smoke and caps explode but this was the first time I had to blow-out flames...good thing I was still there balancing the system when it happened.

Synacom · 05-14-2009, 06:26 AM

It would be interesting to get some feedback from UL on the product if it is listed. One of the things we are seeing in many industries is counterfeit parts. They are knock offs of the real thing, look very similar and even have the UL labels. Please post if you find out any more about it.

Inner10 · 05-14-2009, 09:59 AM

I've already returned the unit, the piece was infact UL / ULC judging by the stamp on the back; that was the first thing I checked. I'm amazed that the flame burned until I blew it out. Trasistor was burned and cracked, wire insulations a little melty and smokey, big resistor beside transistor got pretty nuked also.

Chris Simms · 05-15-2009, 05:56 AM

Its amazing how those things work off smoke. Qnce you let the smoke out....it don't work any more !

Inner10 · 05-15-2009, 04:03 PM

Quote:

Its amazing how those things work off smoke.

Traditionally I'm very carreful not to let the smoke out, but this time I let the flame out too!