amp only partially working! no surround ????

Discussion in 'AV Receivers & Amplifiers' started by sparkymarky, Apr 10, 2004.

  1. sparkymarky

    sparkymarky
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    my yam rxv795a is driving me nuts!

    It has always worked pefectly and has hardly been used really.
    but now it will not decode any surround sound.
    by this i mean it will not put out any sound from my player (via optical lead).

    it won't even do pro logic from skybox (fed via 2 phono cables)


    The amp will output 2 channel (i.e all surround sound types off)
    from Sky but as soon as you move it to pro logic it outputs no sound.

    the dsp program effects like church/stadium etc still work but as soon as you get to pro logic/dd/dts nothing works.


    (btw, when you turn on dvd player the orange dts sign lights up on amp and can't get it off dts. Can't remember if this is normal or not???)


    any ideas please???


    i have tried: unplugging speakers in turn
    -switchin impedance selector
    -tryed a phono lead in the external decoder ports
    in case they are dirty and they player thinks that
    there is offboard decoding going on

    but still am stuck??????????????????? Hellllllllllpppppp!!!!
     
  2. sparkymarky

    sparkymarky
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    test tones also do not work on any channel.


    come on guys!
     
  3. sparkymarky

    sparkymarky
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    just realosed that the first post was not clear.

    basically the amp will only act as a 2 channel stereo amp.

    it wont output anything through the centre or rear channels (although you can 'hear' that the amp is on through the speaker if you know what i mean)



    does anyone know if the centre and rear channels are in fact one amplified channel? unlikely that 2 or three channels have all blown isn't it??
     
  4. bob1

    bob1
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    Try reseting the amp.
     
  5. sparkymarky

    sparkymarky
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    btw not sure whether i did the putting phono leads into external decoder ports right or not. do you have to have the amp set to anything special or input anything to it (i don't have any external decoder)
     
  6. sparkymarky

    sparkymarky
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    how do you reset it bob??
     
  7. bob1

    bob1
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    I don't know but on mine it's just a matter of pressing a button while turning on.
     
  8. lynx

    lynx
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    I don't think this is what you want to hear, however i had similar symptoms (i didn't the amp did) and it turned out to be a blown IC. The two stereo channels worked but the centre and surrounds were down. Of course this may not be the same fault on yours,just an other option to explore if all else fails.
     
  9. sparkymarky

    sparkymarky
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    sounds bad.

    what is an I C lynx???
     
  10. lynx

    lynx
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    Integrated circuit.
     
  11. sparkymarky

    sparkymarky
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    thought so.

    i reckon it may be the analogue to digital converter as obviously it works fine with 2 analogue sources but as soon as you select something that needs digital processing like DD or pro logic (which i believe had to go through the same stage) it stops working.

    i have had my x box on top of the amp and whilst some vents were left uncovered some were covered. i know that ics are heat sensitive.

    how much do you reckon to get it fixed??


    thanks for the replies
     
  12. lynx

    lynx
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    The ic cost around £20, however if you need one and can get the id code check out somwhere like cpc as they stock hundreds of ic's for a few quid.
     
  13. hornydragon

    hornydragon
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    Best bet is take it to a service centre that will have (get hold of) the main Schematic for the AMP and identify the DSP Chip thats knackered and replace it for you. I would expect £40-50 for a pro repair depending on Chip cost.
     
  14. sparkymarky

    sparkymarky
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    thanks hornydragon.

    i think i will do that.

    the nearest service centre is about 80 miles so i will take it there i think.


    if your estimate is accurate then £50 plus £15 petrol should be ok.

    i know its a fairly old reciever now and i have to weigh up getting repaired against a new one, but it does everything that i need. i'm not really interested in 6.1/7.1 or dpl2 so a new reciever would not benefit me , so i think i would rather get this one fixed.

    thanks guys for all your efforts
     
  15. hornydragon

    hornydragon
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    Best to call service centre first before such a long trip mate £50 is guestimate but shouldnt be much more unless Yamaha charge a fortune for the Chip! Get an estimate gone firdt,this should be FOC.
     
  16. sparkymarky

    sparkymarky
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    foc ??????
     
  17. bob1

    bob1
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    Free Of Charge.
     
  18. sparkymarky

    sparkymarky
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    well, took the amp/reciever to a repair chap.

    he took the lid off and a few other bits so that he could connect it to his test rig and it suddenly 'sprung into life' as he put it.

    he offered to do a full board reset although he wasn't sure what it involved and would cost me an extra £30 on top of the £15 i've paid him to diagnose the fault.

    i wonder if it just shut itself down on purpose (as i had an xbox sitting on top of it and it could have got hot) as a safety measure and now this chap has inadvertantly reset the safety mechanism?

    either way i've decided to take a chance and just collect it as it is
    (by the way a new board for the amp would have cost around £150 all in so not worth it).

    i can't see the benefit of getting him to do a full reset as a) he didn't know what it was so there may not be any benefits and B) it must have already been reset in some way and further resttting would have no extra benefit.

    have i made the right choice??
     
  19. sparkymarky

    sparkymarky
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    got it home and it all appears to work. £15 well spent me thinks rather than writing it off.

    Now to see how long it lasts for.....
     

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