Subwoofer Fuses Keep Blowing.

Chris G

First off, I'm not an electrician.

A week ago, I repalced two powered subwoofers for a retail client of mine, (plugged them into the wall and plugged in the RCA jack for each). On Sunday they both stopped working.

Yesterday I opened up one of the old ones that I replaced and changed the fuse. It worked. This leads me to believe that the new ones have blown fuses as well.

I think the subs should have dedicated circuits, no? Is it possible something else is on their circuits and blowing the fuses? They have a microwave and a mini fridge in the back, but I don''t think they would be on the same circuit as the subwoofers (although the fridge an microwave are most definately on the same circuit as the amplifier, in fact the amp shares space with a whole slew of crap on a power bar, but I can't believe a wonky signal from the amp would blow two subwoofers simultaneously, and isn't the fuse there for ac protection, not low voltage...sorry long bracket thought, and I'm getting in over my head with attpempt at theories).

I've talked to the manufacturer (Paradigm), and the supplier, and it's still a bit of a mystery. So perhaps it's a question for an electrician, (go figure). I just assumed the manufacturer would be qualified in electrics so I never bothered to ask before. BTW, is there a certain type of electrican I should be hiring for this?

mdshunk

Are they driving this sub with a component level or line level RCA input? That blown fuse in the unit has nothing whatsoever to do with the electrical source to which it is connected.

Chris G

An RCA jack runs from the Pre out on the amp to a high pass controller (Paradigm x-20) and then rca out from there. Not sure if that answers the question.

Chris G

Just in case pics help..

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DaveTap

Marc are you sure? I've seen some powered subs that had fuses both in series with the DC power supply, and the outputs. But your right the incoming line shouldn't have an affect.

Chris where are the fuses? On the amp output or power input?

mdshunk

No... I've just never seen fuses in the power supply on a powered sub, is all. Just the output.

Chris G

I "think" they are on the power input. I have one of those chirping circuit testers and when I held it to one end of the fuse, (the burnt out fuse when it was still in the old sub) it didn't chirp. And I only had it plugged in to a wall receptacle at the time. Replaced the fuse..chirp on both ends. Does that make sense?

I just took off the back cover of one of theold ones and took a pic. The fuse is near top left...don't know if that helps.

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DaveTap

Hi Chris if that black wire is your power cord I'd guess the incoming power too. But there might be a quick easy test... is there a LRL? (Little Red Light) or power indicator? Othewise get out your volt ohm meter.

Sparky Joe

Dude, it looks like a they have a few bucks tied up in their stereo system, run a dedicated circuit (no microwaves or fidges or whatever else on it) Then buy a good surge protector, perhaps even one that connects at the panel.

If any fuses or woofers blow from there it's manufacturer problem or user problem.

Or the guy that connected it screwed it up, sorry to burst your bubble.

Plan 9

There's a loose neutral and this is a 3 wire circuit. The equipment is occasionally getting spiked with 240 volts.

Man I'm good.

Chris G

It's an auto on system. It needs power form an outlet, and a signal from the amp to turn on, so no LRL..

Money is not an issue.

I'm the fourth person to look at their system. The previous three were all audio installation companies. One of them wired the satelite speakers out of phase, the other switched the calcualtor adapter with the x-20 adaptor, (12v vs 24v). The other showed up and ran off. This has been a nightmare for my client. This is a large company, (3000 employees 200 stores). This is their flagship store with an ugly sytem. My client is freaking because the PO's for this are takiing a life of their own. They're desparate. Why in the hell else would they ask there general repair guy to fix it?

Also, the subs are 20 feet above ground level, and I need a scissor lift to take them down each time. Although I think I can open up the back and replace a fuse while I'm on a ladder.

If a dedicated circuit would fix the problem, then I'm a happy man. Call an electrician, close the docket and get paid. Bu I can't keep asking the client to fork over money for a "possible" fix, (money is not an object to fix the problem but it is to experiment with the problem).

So, what causes a fuse to blow? Is it a surge from the power line or from the amp? Remember, both subs blew at the exact same time. Slow burn fuses, if that matters. The last person to work on the amp was a recording studio technician, (that I hired, he fixed the out of phase problem). He works with million dollar systems everyday, so I trust he did it properly. He is also a little miffed too.

It's tough one because the problem appears to lie in a grey area where audio technicians and electricians cross.