JVC rx-7010vbk issues

Discussion in 'Archived Threads 2001-2004' started by SteveTomassetti, Feb 2, 2002.

  1. SteveTomassetti

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    The following was a review on another site for my receiver...

    Measured 1.5 Volts of "Zero Crossing Distortion" on the Center, and the left and right Rear Surrounds Channels at a -10db at 1K Hertz input leve. At a 5 volt output that's a whopping 25% distortion. Swept through the whole audio spectrum 20-20K Hertz. Got the same results. Front left and right Main channels look real clean. Sound clean too. Probably because JVC has bias trimmers on those circuit board for adjustments. You can look right through the ventilation opening on the top to see this. On the other channels the bias trimmers are missing and no provisions(holes drilled and solder pads) have not been made for the adjustment trimmers or fixed resistors. Center channel at low SPL is unbearable to listen to. Cliff Dryesdale's (tennis commentator) voice that distorted will cut you like a knife.

    I emailed the reviewer further and here are more of his responses...

    On the 7010 I could see through the vents in.top cover 5 printed circuit cards mounted from front to back in the amp,slightly right of center. Two of the PC's have little trimmer potentiometers on them which I assume is the bias resistor on the emiiter side of the power transistors for the right and left channels. The bias voltage for the Center, LR, & RR surround power sections probably have fixed valued resistor which determine the bias voltage. I could not see the little trimmers on three of the PC card. By using a tone generator and a scope and removing one of these fixed resistors and replaceing it with a variable resistor (trimmer) you can adjust the bias voltage for the lowest value of distortion. Then with a ohm meter measure the value of the trimmer at this low distortion point and repace it with a fixed resistor of this exact value. Then repeat the same steps for the other channels. If I had some schematics it would make the job easier for locating biasing resisotor. Maybe the schmo's are on JVC web-site. If I were you I would contact someone at JVC and bitch to high heaven for them to fix it for you or give you a new one or better yet your money back. Threaten to sick The Better Business Bureau on them or tell em your going to contact Sixty Minutes.

    Do I have any hope in getting anything from JVC here? Anyone have any advice on what I should do?
     
  2. SteveTomassetti

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    any ideas? or am I screwed?
     
  3. Vlad Gurovich

    Vlad Gurovich Auditioning

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    Steve, do you actually have any problems with the receiver, like the ones the reviewer mentioned? Because I dont...
    I havent run it through any specialized tests, but the Sattelite TV broadcasts and DVD sound fine, the latter being Dolby Digital 5.1 sound. I tested it with matrix shootout scene and the sound was sensational. Of course i am not using high end speakers with this receiver, just the Hitachi 702HT 5-Piece, 100-Watt Home Theater System I got for $80 from amazon last year.
    Do you have any specific problems with the JVC RX-7010 receiver or that reviewer made you concerned?
    BTW Here is the link to speakers(Amazon doesnt carry them anymore, but it has some info on the set)
    http://www.amazon.com/exec/obidos/ASIN/B000056BM9/
     
  4. SteveTomassetti

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    Vlad,

    Yes, I have had the problems, which led me on a search for the solution. I took the unit to an authorized dealer and pretty much got yelled at saying the unit was performing to spec. I play scenes like the Matrix lobby and others, any yes, it does sound great... I only hear the distortion on voices, which makes normal movie watching unbearable. Picking the scenes that push your system to the limit sound great because it drowns out the distortion. I've emailed, wrote, and called JVC multiple times and I get the same answer... take it to an authorized service center. It just sounds like is a poor unit. I'm selling it and getting a Denon, constantly tweaking and modifying a receiver right out of the box just for it to sound OK is ridiculous.

    I'm using a HTD level III speaker setup.

    Thanks
     
  5. Vlad Gurovich

    Vlad Gurovich Auditioning

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    Can you point me to a specific example of distortion? Does it happen all the time there is a dialog? Any particular scene in Matrix that gets distorted? I just wasnt able to reproduce your problem...Sports commentators during olympics sound just fine....
     
  6. SteveTomassetti

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    Interesting...

    The distortion is from the center channel only. If i cut off the center and divert it to the mains, dialogue sounds great. I've used 3 different center speakers and all have the same results. I finally came to my wits end when watching the Tron 20th Ann. edition. The first scene in Dillinger's office with Alan,its only dialogue and it is unwatchable. Other movies where it is obvious: LA Confidential: DeVito's commentary at the very beginning of the movie, T2: Sarah Conner's opening commentary while panning thru the scenes of destruction. It is more obvious the lower the volume. I'll pop the Matrix in tonight and find a scene, but basically its any scene with just talking and no music or sound effects. It may be a problem with just my receiver, but I have had it to a service shop, where they basically told me I was crazy. Thanks
     

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