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Audio Research Pre Amp Problem


zuzu

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My SP 11 tube pre amp is not playing one channel. The other channel is playing great.I swapped everthing in the system including all the interconnects. Put in new tubes. even changed power amps. If I change the speaker connections from the power amp the other speaker plays. Not the speakers or speaker cables or the power amp. Once and only once I got both speakers to play by switching the CD inputs on the pre amp. I put on a different disk and one channel dropped out again. With everything set up correctly it's the right channel that is dead.

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Same thing happened with the sp8 I used to own.  Take the top cover off (after you turn it off/unplug and let it discharge) check the right channel.  AR uses fairly thick gauge wire on the in/outputs.  I found mine disattached and had to solder it back on, it could be loose a bit or barely making contact and that would explain the intermittent sound. Hopefully that is the only problem, definitely worth a look.

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Talked to ARC factory technician. He said to swap out the interconnect again with a different cable. Check the input solder connections as mentioned above, take the tubes out and put them back in, and [now here is the good part] Rotate all the knobs from one extreme to the other 50 to 100 times and likewise flip all the toggles 100 times. My Sp 11 is 25 years old and all my listening has been with a Cd player for the past 10 years. The unexercised knobs and toggles [which are self cleaning when moved] will clean themselves. I can't see if the pre amp works now because I sent my RF-7 crossovers to Dean. I should have them back in a few days. Stay tuned.

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  • 2 weeks later...

Did all the things suggested. Right channel still not working. Left channel sounds great. Unit has light dust all over everything. Do I dare get an air can and blow it off. Is there any technique to doing this once the cover is off? I see no mention of a fuse by anyone. I don't even see any mention of the unit having a fuse in the manual. In a schematic, which I have, what is the symbol for a fuse? My best guess is there is a loose or cracked solder connection that my eyes and skill can't detect. Could a TV techy with a meter, be smart enough to find such a solder crack or am I advised to send this back to the factory? YIKES!!!!

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The symbol for a fuse is a pair of little circles with a wiggly line between them...

cs_fuse1.gif

See here for more symbols: http://library.thinkquest.org/10784/circuit_symbols.html

Some equipment that use hex nuts to hold the RCA jacks can allow these jacks to rotate slightly, especially if you twist when making/breaking the connections. If you can open it up and inspect the insides you might find a broken/loose connection...

A tech could certainly help find problems. There is a method used to examine the circuits by starting at the end and working backwards by using a noise pop - when the pop disapppears that is where you look for the disconnnect... this takes some experience and instruments to perform.

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How about sending the unit back to Audio Research?


Cant do that. Because well, that would make SENSE!

Ah come on... Its allot more fun to watch a bunch of folks who cannot see the unit make guesses.

And after this pre-amp, I know of a truck that everyone can start making guesses about!

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How about sending the unit back to Audio Research?

zuzu seems to be having more than his share of trouble with his Audio Reseaech gear (CD player problems: http://forums.klipsch.com/forums/thread/890186.aspx ). I guess that it just works out that way sometimes, but I have used AR stuff on and off for a long, long time (now using an AR VT-100 amp... it's "a keeper"), and have never had a problem... not a one. Zuzu, I agree that you might be well advised to get on good terms with the folks in the Audio Research service department. Here's wishing you much improved "luck" with your great AR equipment!

Rob

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I'm extremely happy with my ARC gear. This is the first problems I ever had. The CD player seems to be fixed. The tech [Chris] at ARC talked the local tech thru fixing it on the phone. The SP 11 and its power supply are going back to the factory today, for the first time in 25 years, For cleaning, 6 relay replacements, new caps in the power supply, new tubes, and whatever else they recommend. When they get back, I'll start listening to my new Dean crossovers and then set up my new velodyne sub. Thanks

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