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PostPosted: Wed Sep 06, 2017 11:49 am 
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Joined: Wed Sep 06, 2017 11:30 am
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Location: Thessalon, ON, CA
I recently bought a Pioneer SX 880 at an auction , untried for 40 $ , clean as new . Got it home hooked it up to some equally old Yamaha NS 680 speakers . Sounds absolutely fantastic until halfway on the volume then it will hit bit of a loud peak and then it shuts down the music , needles drop then in a couple seconds you can hear something click inside and the music comes back until it hits another peak then it does it again . Stops when the volume is turned down below half . Very frustrating . I'm guessing its some kind of relay or something that is tripping but I don't know . Any ideas , anyone ????


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PostPosted: Wed Sep 06, 2017 12:26 pm 
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Joined: Sun May 28, 2017 1:25 pm
Posts: 63
Location: Toronto, ON, CA
Quite often the relay will shut down the unit because there is a short somewhere-speaker wire or speakers. You could have a faulty driver in the speakers .But make sure your speaker wires are clean and the positives and negatives are not shorting.Also, try shutting off the speakers and using headphones to see if it still does it.


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PostPosted: Wed Sep 06, 2017 1:58 pm 
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Joined: Sun Oct 02, 2011 3:20 pm
Posts: 42
Location: Port Coquitlam, BC, CA
skunkroaster wrote:
I recently bought a Pioneer SX 880 at an auction , untried for 40 $ , clean as new .g . I'm guessing its some kind of relay or something that is tripping but I don't know . Any ideas , anyone ????


If you have a DVM or VOM check the receiver's speaker output and measure the DC voltage for each channel. The reading should be close to zero volts ideally with the volume control set to minimum.

There are 3 reasons why the output relay protection kicks in and disconnects your speaker.

1. Excessive DC offset from the power amplifier output. The one I asked you to check above
2. Too much output current demand which can be a combination of volume level and speaker impedance at a specific frequency
3. I dunno. That thing is about 39 years old. At that age, a full rebuild is in order if you expect it to work at its full potential. Anything can go wrong.

Resist the temptation of adjusting any of the trimpots or spraying DeoxIT.


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PostPosted: Wed Sep 06, 2017 3:04 pm 
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Joined: Wed Jul 23, 2008 5:04 pm
Posts: 1642
Location: saskatoon, SK, CA
Or bias is way too high.
If checking dc offset may as well check the rest too.

Yamaha ns680?
Owned 670 and 690...never heard of 680s


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PostPosted: Wed Sep 06, 2017 4:16 pm 
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Joined: Tue Jun 14, 2016 8:33 am
Posts: 1031
Location: Kingston, ON, CA
It may be big and heavy....but it is not a beast.

And running it at half volume is running it hard. Punishingly hard, especially when it is that old.

It's like taking a geriatric who's never worked out and forcing it to run a marathon, at gunpoint.

Failure is guaranteed.

That amp needs to be thoroughly checked out and totally re-capped before you do such harsh things with it.

Please, stop beating on it and forcing it to the failure point.

the capacitors in that unit are now...40 years old. Forty years old. You're lucky it works as well as it does and has not blown up yet. Stop, just stop.

_________________
(Ken Hotte, of) Teo Audio


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