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Help replacing a relay in an Alesis amplifier.

 
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PostPosted: Fri Sep 12, 2008 8:20 pm    Post subject: Help replacing a relay in an Alesis amplifier. Reply with quote

I have an alesis rs300 amp that I actually don't hate as much as I probably should. I know virtually nothing about electronics but I know how to solder and I know a little bit about components. The amp has stopped passing audio. When I turn it on, it would usually take a few minutes before it started working. Right before it would pass audio, I always heard a click sound, which I believe is the sound of a relay switching. Now when I turn on the amp, I never hear this click, and the amp never passes audio. I've looked inside and as far as I can tell, there is only one relay. It says DW321-D12s. I believe it is 12v 10a. Other that that, I really don't know anything. I believe this relay to be the problem. How do I find one? What other information about the relay do I need to know to find one to replace it? I believe if I find the part, I can have a friend install it for me if its beyond my abilities. If this is the wrong place for my post, im very sorry. If you know of a more suitable forum for questions like this, please let me know.

Thanks a lot!

Nick
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Sat Sep 13, 2008 5:55 pm    Post subject: Reply with quote

I am not familiar with the specific amp but I can tell you that basically relays are used for means of protection in amplifiers & majority of the time it is NOT the relay itself that is causing the problem.
While it is possible for any relay to fail(unusuall), probably it is not energizing because of some type of fault; either a supply or output stage?
Any competent tech with a meter should be able to test a relay in the circuit & determine why it's not energized.
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Mon Sep 15, 2008 9:14 am    Post subject: Reply with quote

Most likely, that relay is used to disconnect the speakers from the power stage in order to salvage them in case of a serious fault in the amplifier (i.e. a broken down output transistor causing it to deliver DC to a speaker, or a high freqency oscillation). If the relay not gets energized when you turn the amplifier on, then it is probably either a fault in the protection circuitry or a "real" fault somewhere in the amplifier.

In some PA amplifiers (for instance, Mackie rack mount units), those protection circuits use very high impedance circuitry and are sensitive to leakage currents due to dirt or moisture. It is very common that such amplifiers fail to operate on rainy days or in winter, when just taken in from a cold car. The reliability can be somewhat improved by thorough cleaning of the relevant areas of the PCB and coating with a suitable insulating varnish.
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