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Faulty AR-8s - Repair?


Djotsky

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Hello, Good Folks of Classic Speaker Pages, 

I am in a bind with one of my AR-8s's and during my research into the problem, a couple of sources on the Internet have pointed back to this website quoting the formidable knowledge base regarding Acoustic Research products. So I hope you can help me! 

I bought a pair of AR-8s's off my uncle about a year ago, along with an old Cyrus amp as part of a long-term hi-fi project. I used the setup occasionally and it sounded fantastic but it largely went unused. 

Cut to last Saturday,where I was gifted a record player and decided to hook everything up. But lo and behold, my left speaker wasn't working! 

I'm getting absolutely nothing from a speaker that was working perfectly and I can't quite put my finger on what the problem is. 

1. The negative terminal on the speaker is broken and will not hold the cable, but I am fairly certain that there is a good contact between the copper and the terminal contact (when the cable is wedged in there. Rough, I know). 

2. I have removed the speaker terminal assembly and found all of the wiring to be in good order, including the capacitor behind it. The capacitor does show signs of being burnt out (pic to follow) but even that is so minor that it could just be a speck of glue or a mark left from a soldering iron. 

3. It's conceivable that the amp output is faulty, thought I suspect I would have noticed a smell of burning electronics once I turned it on. 

I will post some photos when I get a chance. I am no stranger to a soldering iron so if it was just the cap, I'd be laughing. I would also like to fix the negative terminal  but the terminal unit is covered in glue and looks to be a sealed unit, so I would rather hear someone's advice on what to do there before chipping away at the glue. At the end of the day, it can be replaced with hotglue but I would rather go in with some idea of what is going on!

Does any of this sound familiar to anybody? Let me know if you need any more information!

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To check if the amp output (or something ahead of the amp in the signal chain is at fault) swap over the amp connections so that the left amp output now feeds into the right (working)speaker, and the right amp output now feeds the left (silent) speaker.

As can be inferred from jason4300's suggestion, if the left speaker stays silent, and the right speaker plays OK, then the problem seems to rest with that left speaker. If the left speaker is now OK and the right speaker is silent then there is a problem in the signal chain ahead of the speakers. It could be the amp or the source ahead of the amp

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Thanks for all of the responses, everybody! 

All of your suggestions were excellent. I, of course, did none of the basic troubleshooting that you suggested and immediately decided that the speaker was at fault. More fool me! I probably did this because the player is new and sure, how could a thing that is new be broken? 

Anyway. Here are the results of the tests suggested above:

Note: All tests were carried out using the player's RCA output unless otherwise noted.  

1. I swapped the Amp output to the Speakers around and the sound moved to the Left Speaker. 

2. I tried a different source into the same input to the amp and got stereo, so I realised then that both speakers were working. As a direct result of that experiment, I will not be posting a photo of the suspicious capacitor because I am not arsed opening up the speaker again. 

I think it's therefore reasonable to assume that the Amp and Speakers are working. I suspect the problem lies with the record player. It's a Grausch RPS100, the outputs are standard RCA and a headphone jack. 

It appears that the operation of the RCA output is a little funky, as is the headphone jack output. If I connect the player to the amp via the headphone jack, the sound is much quieter and primarily comes from the Left Speaker (a little does come from the Right Speaker). As for the RCA output, I'll describe it's operation here and if this appears to be familiar to anybody, let me know what you think is going on: 

1. If the L and R cables are connected properly, I only get sound from the Right Speaker. 

2. If I then remove the L cable from the back of the player, the sound continues to issue from the Right Speaker. 

3. If I then remove the R cable from the back of the player, the sound ceases. This all makes sense so far. 

4. If I then plug in the L cable to the L receptacle, the sound issues from the Left Speaker. 

5. If I then plug in the R cable to the R receptacle, the sound issues from both the Left and Right Speakers but then the sound to the Right Speaker will drop entirely after about 10 seconds. 

This doesn't make a whole lot of sense to me. Is my player broken or does it only output mono or something? I have inspected the electronics inside the player and nothing appears to be disconnected or broken. 

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Hi and welcome.

I'm a little confused. Never heard of the Brausch RPS100. Googled and found the Grausch RPS100. Guess that's it but it seems to be sold in the UK or Europe. Have no experience with it.

But I agree the problem is somewhere in the turntable or cartridge. Is there a typo in your item 4? Do you mean plug the L speaker into the R jack? Or are you saying the L jack works when there is no speaker connected to the R jack?

6 hours ago, Djotsky said:

4. If I then plug in the L cable to the L receptacle, the sound issues from the Left Speaker. 

Point #5 seems to contradict #1.  Usually the L channel is out, but after unplugging cables and plugging them back in, it's the R channel that's out? It's a puzzler.

Be sure to check the little wires going to the cartridge.

-Kent

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20 minutes ago, JKent said:

Is there a typo in your item 4? Do you mean plug the L speaker into the R jack? Or are you saying the L jack works when there is no speaker connected to the R jack?

Point #5 seems to contradict #1.  Usually the L channel is out, but after unplugging cables and plugging them back in, it's the R channel that's out? It's a puzzler.

Be sure to check the little wires going to the cartridge.

-Kent

No sir, you read that correctly! If sound has been issuing from the Right Speaker and I unplug both the cables, then plug the L cable back into the player's L receptacle, sound then issues from the Left Speaker. Then if I plug the R cable back in, I get stereo for about 10 seconds before the sound drops from the Right Speaker. 

I will inspect the cartridge wiring more closely tonight and see if anything is amiss. 

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