Restaurant sound system not working

[DanteK]

Now, this isn't much of a "computer hardware" issue, but I'll post it anyway since I like this forum and it's still somewhat relevant.
Anyway, forgive me for not using proper terminology or having a lack of knowledge, I'll do my best to explain so bear with me.
Anyway, my family owns a restaurant, and the sound system (which consists of cd player -> A/V receiver -> lots of speakers) has botched after a night of loud music.
Now, I don't really have much info on anything, and nobody else seems to know much, so this involves a lot of guesswork. From my knowledge, some guy went there (don't know him, don't know if he has qualifications) to check the A/V thing to see if it works, and said that it's fine, but that a speaker is dead and is causing the A/V receiver to stop the circuit so it doesn't fry (or something along those lines). From what i remember, the word "LOAD" appears on the front of it. Now, today I went to try to get it to work with a different speaker (got some small sony one, 6 ohms), and plugged it in the 4 ohm output (forgot how many volts), with music coming from my phone. It didn't work no matter which config I tried (aux 1, aux 2, all speaker outputs), which leads me to believe the receiver is the thing causing the problem. There is an LED for "signal", which i assume should light up when sound is picked up from the inputs (I'm using a 3.5mm from phone to dual RCA on the AUX 1/2 inputs). The back speaker outputs are pretty weird, they're these square pieces of metal with screws to keep the cables in place when screwed in, can take pics tomorrow if needed. I think I'm wiring it right, 1 wire to the 4 ohm X Volt output and one to the output next to it (i think it was labelled COM or smth), though i tried it a few different ways to be sure. No luck.
So, the cables themselves are already there, and I think they all work, but I don't know how they connect the speakers (parallel/series), though everything was working fine up until now so i doubt that's the problem. The cables are in 2 groups of 3, I assume positives of inside/outside/bathroom and negatives of them. They are just bare cables on the ends, and from what I know just get placed under the metal plate and screwed in. I think if one of the speakers is failing and is affecting the rest, I would be able to buy a single speaker and replace them until everything works, but even so the other 2 groups of speakers (e.g. indoor + bathroom) shouldn't really be effected I think.
Anyway, I'm thinking of getting a similar or slightly more powerful A/V receiver and replacing it to see if that'll fix things, then if there's also a speaker problem buy one and replace them till music plays.
What do you guys think I should do?
Any advice? Or should I give up and get them to call in a professional to fix it?
I can try to give more info if needed.

[Matacks]

Okay, well I hope that you're able to get the information you need to fix that.   

 

Do you happen to know the model of the A/V receiver that you have in your restaurant?  This would be good to know.  If you could track down the manual to your particular model of A/V receiver or even find one online, that may help too.   

 

I think you are on the right track by trying to test the speakers separately.  A good thing to try may be to just hook two speakers up to the the receiver in a stereo configuration and see if it outputs any sound.   If trying to hook up two speakers doesn't work, that could be an indicator that the A/V receiver is broken. 

 

As for the speaker wire, I understand about the difficulty of figuring out the correct polarity.  You may find some help by looking really closely at the wires.  Often times speaker wire will have some very faint - or + symbols printed on to just one of the wires to indicate polarity.  Other times one wire will just have a stripe that runs along the entire length of the wire.  The striped wire is usually used to indicate the negative wire.  

 

Hopefully the receiver is not broken but if it is, buying a new receiver should fix the problem.  I'm not certain what type of receiver you would need for a restaurant though.  I've only used these types of things to hook up a home theater setup in a living room.

 

good luck

[Sors]

First, I would do a test without any speakers plug, just to see if the receiver doesn't have a problem by itself, if the system is not giving you that load error message without any speakers plugged in  then I would plug only the new speakers you are testing and check again.

[ShearMe]

Can you take a picture of the back of the receiver, and maybe some wires?

It sounds similar to a unit they had at a previous job which I fiddles with a fair amount.

[creatip123]

I'm thinking out loud, but is it possible the AVR got a protection fuse that got blown the first time it showed LOAD error? If that's the case, it's actually a good thing, as fuses are dirt cheap. Some fuses cost under $1. 

[Lutkeveld]

@DanteK

Do you have a multimeter? Unplug the wires from the amplifier and measure the resistance from + to + from each speaker pair.

They should all be around 3.5 or higher (that's the common resistance of a 4 ohm speaker). 

The dead pair is probably overdriven and has a blown voice coil (which measures as a short-circuit).

The lower the resistance/impedance, the more power the amp will push. WIth a dead short the over-current protection will be triggered.

So you need to open the amp and search for a blown fuse. Do you know how it looks?

[DanteK]

I tried the amp with one of my speakers (which i know works). It should've been more than powerful enough to power it by itself, but no sound, which lead me to believe the amp was broken. 

I think the actual power amp part may be working, but the sound signal isn't getting through to it. Could this be because of a blown fuse? (also I don't have a multimeter)
A friend told me they have a receiver which they don't use anymore, so I'll to try that out (assuming it has the right connectors), and if not I'll buy a new one.
Even if a speaker is blown, I think the other 2 circuits should be working with no problems. 
I'll take pics and note mode numbers if I run into more problems, but thanks for suggestions.

[Lutkeveld]

Yes, that could be. You can see when a fuse is broken or not, so it's easy to detect and replace.