Audio issue

[RobertN]

I am puzzled by issues with my stereo.

I have an older mid 80's(I got it new in '85) Yamaha A-700 integrated amp. Pretty decent older unit, 105wrms, 0.005thd at 8 ohms. The thing is built like a tank. Pop the top and there is a heat sink set that could cool a house. It is hooked to a set of Bose sattelite system with a passive sub. Pretty basic system. The DVD player, CD player, tuner, cassette, and yes, a turntable, are plugged in.

A few weeks ago, it started clicking on for 5 seconds, off for 5 seconds. Not the main power, but the speakers. It has always had a 5 second delay at powerup; there is a relay in the circuit. I have not had time to tear in to the unit till tonite.

I checked speaker and subwoofer connections. They looked fine, so I pulled the amp out, popped the top, and blew the dust out. Everything looks fine; no signs of overheating ect. I couldn't find anything visibly wrong.

I have a stereo, with a 5 cd turntable, in the garage too. I have some funky old car speakers hanging from the rafters(2). I also have a nice set of RCA in/outdoor speakers on the front patio hooked up.

So, I disconnected all that stuff and hooked up the Yamaha. Wanted to see if I could hear the relay cut out with the lid off the amp. Everything worked fine... I turned it up as much as I could without blowing the old car speaker; this is with both A and B turned on so the car speakers and patio speakers were going pretty good. It still worked fine! It's not the same load as the Bose, but if it was a load issue, the garage/patio combo should have made it tweak out.

Any idea what to look for in the sattelite/sub system? I wonder if a cross-over is flaky or something. I was going to check it with an ohm meter; not sure what to expect...

This has been a solid amp. previously I have had bigger speakers attached. I had a set of JBL's a while back that could shake a house off it's foundation. The thread about Klipsch peaked my interest; I would love to get another set of high end speakers hooked up some day...

 

[_RaT_]

I am puzzled by issues with my stereo.

I have an older mid 80's(I got it new in '85) Yamaha A-700 integrated amp. Pretty decent older unit, 105wrms, 0.005thd at 8 ohms. The thing is built like a tank. Pop the top and there is a heat sink set that could cool a house. It is hooked to a set of Bose sattelite system with a passive sub. Pretty basic system. The DVD player, CD player, tuner, cassette, and yes, a turntable, are plugged in.

A few weeks ago, it started clicking on for 5 seconds, off for 5 seconds. Not the main power, but the speakers. It has always had a 5 second delay at powerup; there is a relay in the circuit. I have not had time to tear in to the unit till tonite.

I checked speaker and subwoofer connections. They looked fine, so I pulled the amp out, popped the top, and blew the dust out. Everything looks fine; no signs of overheating ect. I couldn't find anything visibly wrong.

I have a stereo, with a 5 cd turntable, in the garage too. I have some funky old car speakers hanging from the rafters(2). I also have a nice set of RCA in/outdoor speakers on the front patio hooked up.

So, I disconnected all that stuff and hooked up the Yamaha. Wanted to see if I could hear the relay cut out with the lid off the amp. Everything worked fine... I turned it up as much as I could without blowing the old car speaker; this is with both A and B turned on so the car speakers and patio speakers were going pretty good. It still worked fine! It's not the same load as the Bose, but if it was a load issue, the garage/patio combo should have made it tweak out.

Any idea what to look for in the sattelite/sub system? I wonder if a cross-over is flaky or something. I was going to check it with an ohm meter; not sure what to expect...

This has been a solid amp. previously I have had bigger speakers attached. I had a set of JBL's a while back that could shake a house off it's foundation. The thread about Klipsch peaked my interest; I would love to get another set of high end speakers hooked up some day...

Probably have a voice coil in the mid or woofer that is exceeding the minimum ohm rating on the amp (typically 4 ohms) which causes to much current through the thermal overload protection or breaker. My guess is you were listening to ZZ Top cranked up to high and melted some wire on the speakers windings. Adding in A and B speakers still keeps a load of approximately 4 ohms to protect the amp. Continued high current driving will trip the amp output protection. I've blown the woofers on my ADS, M&K and KEF speakers. I don't listen nearly as loud anymore and have a Adcom 555II power amp so I rarely clip my speakers.

 

[goaliedad]

silly question- have you hooked it back up to the original speaker system? could you have "fixed" the problem while cleaning and inspecting?

 

[Soundguy]

I'm not sure what ODP that amp has.. but I'd be inclined to think as the others.. It was dropping into an Output Device Protection mode.. thermal or otherwise.. and cutting out. ( some newer systems use ACL as a method ODP .. and you won't hear a cutout.. but rather distortion.. ).

I agree with the others.. hook it back up and check it. If it's ok.. i'd say it was dirty and something may have been getting hot.. If it isn't working.. then I figure there must be a fault at the input of the load, or in a non-isolated stage of the load.

Soundguy

 

[RobertN]

I checked the sattelites; each was about 4 ohms. I checked the passive sub; one channel was about 5.6ohm on the input and output. The other channel was about 4M ohm. Something funny is happening there.

I tried pulling the input panel off the sub, but it will not come out of the box all the way. It's like they had it installed in the side panel, hooked up to the sub, and then assembled the whole cabinet together. The circuit board on the inside is bigger than the hole... No other screws are visible.

I always wanted a powered sub... Don't want to pay the $$$ at the moment though.

 

[_RaT_]

Try pulling the woofer itself out, on many older models, thats how you pull the crossover out of the box.

 

[RobertN]

There is no obvious way to disassemble the box. That is the puzzling part. It's like they hooked up all the parts, and then glued it all together. I've looked it over closely for screws and fasteners but have not found anything. I don't want to bust it open.

It was probably affected by Stevie Ray Vaughn... Or, I have cranked Tull's "A classic Case". Locomotive Breath sounds pretty cool with a full symphony backing it up! I don't tend to crank the Bluegrass as much...

 

[_RaT_]

I think Locomotive breath killed a few woofers in my younger days or was it Allman Brothers Jessica, or was it Eric Clapners Layla, no, come to think of it, I think it was Locomotive Breath. It was Paul Simons Kodachrome that ate a tweeter.

 

[Soundguy]

Try pulling the woofer itself out, on many older models, thats how you pull the crossover out of the box.

Not just the old ones.. I've got some concert series EAW bi-amp'ed cabinets flown at one of the gig's i work at.. and you have to take the 15's out to get at the passive crossover...

That's a nice job up on the lift...

Soundguy

 

[Soundguy]

I'm a 'tull fan myself... aqualung and locomotive breath are my favorites of his. Of course there's sabath.. and the old kenny rogers ( and the first edition ).. like.. 'what condition my condition is in'... excelent use of a flanger and a rotary speaker.. probably a leslie.. etc..

Soundguy