NAD 7140, Strange problem, help?
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NAD 7140, Strange problem, help?| Oktyabr |
Posted: May 26, 2009 12:14 am
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 Advanced Member  Group: Members Posts: 569 Member No.: 133 Joined: January 01, 2007  |
Just picked up a NAD 7140 stereo receiver for free with some speakers I purchased. I got it home, plugged it in, hooked up some speakers and an antenna and no sound. Played with it for awhile and noticed the AM/FM button was sticking. Cleaned the contacts on that and now it tunes in the radio but here is the strange part...
In STEREO mode the right channel almost sounded blown in both A and B selections. On closer examination I noticed that while the right channel(s) are producing sound it is as if the mid to lower bass frequencies are chopped off... only the highest mids and highs are present. The left channel(s) work as expected. I tried swapping out the speakers, the wires, and tried different FM channels with the same results. Here is were I am a bit baffled... When I hit the MONO switch both speakers work great, albeit not in stereo! So what's the deal here? If it was the output section of the amp shouldn't stereo/mono make no difference? I suspect it's directly in the FM tuning section but can't for the life of me figure out why it would be channel dependent... of course I am no radio technician either! Tips? Theories? Similar experiences? A good radio repair shop in the Puget Sound (Washington state)? EDIT: Just hooked up a CD player to it and both channels work great so it's obviously a problem with the FM section? Thanks in advance! This post has been edited by Oktyabr on May 26, 2009 12:23 am -------------------- Main: Yamaha RX-V663 -> Vampire Wire CC1M ICs -> Yamaha M-80 (lows) & Yamaha M-65 (highs) -> Monster Powerline2 x 2 -> Teledyne AR9
Late night: M-Audio Delta 44 -> Creek OBH-11 -> ATH-M50 ----------------------------------------------------------------------- Long gone but not forgotten: Snell J/IV, E/III (x2), A/IIi; Sachiko BLH; Yamaha NS690; ADS-L810; Cerwin Vega DX-9, D9, etc.; Teledyne AR9LS, TSW910; Polk SDA-2; Magnepan MG1, MG2; Dahlquist DQ-20i, DQ-30; Infinity Kappa 6.1v2, WTLC; Vandersteen 2C (x2); KLH Model 23; Advent L, NLA; Pioneer CS99A, CS88; to be continued... |
 
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| dingus |
Posted: May 26, 2009 12:55 am
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 How can people be so cruel?  Group: Admin Posts: 5648 Member No.: 3 Joined: June 29, 2006 |
the switch could be dirty ... beyond that i'm afaid i cant help.
-------------------- Teledyne AR9, Yamaha B-2x, Yamaha M-2, Yamaha C-2a, EAD DSP 1000, Squeezebox v3, Wadia WT-3200.
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| Jim Eck |
Posted: May 26, 2009 03:01 am
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 One of Jerry's Kids Group: Moderator Posts: 3876 Member No.: 38 Joined: July 12, 2006 |
I'm with dingus, clean the switches, do the mono and the am/fm button, while you are at it clean all of the posts and switches for good measure.
Jim -------------------- "Son, let this be a lesson to you: never do tequila shooters within a country mile of a marriage chapel."
- Al Bundy Fairchild 412-1B SME arm Pickering XSV-3000 GAS Thoebe Grant Fidelity B-283 California Audio Labs Delta Transport Paradesea DAC DBX-3BX-DS Sansui TU-7700 Adcom 585 Hafler Pro 500 Legacy Classic's Tube system Scott 299B, Thorens TD-160, Klipsch Heresy's |
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| socal sam |
Posted: May 26, 2009 05:35 am
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 Millenium Member Group: Members Posts: 1133 Member No.: 265 Joined: July 25, 2007 |
Also, clean the tuner trimpots. NAD used the cheapest trimpots and they easily corrode.
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| clint e. |
Posted: May 26, 2009 06:55 am
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 D161t@L 0N L1N3 / Analog at heart Group: Moderator Posts: 6194 Member No.: 40 Joined: July 13, 2006 |
Also, look for some broken solder joints or a bad ceramic cap. Nad use to have those in FM section of older units.
BTW, did you tried with another antenna cable? IMO, i found some FM cables to work great with some receivers, and very bad with others. --------------------   "It occurred to me by intuition, and music was the driving force behind that intuition. My discovery was the result of musical perception." (When asked about his theory of relativity) - Albert Einstein |
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