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No noise from NAD.. ?

Discussion in 'General Audio Discussion' started by 50nstillhifi, Aug 16, 2018.

  1. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
    Carolinas
    P1080756.JPG P1080760.JPG P1080764.JPG Got my hands on a NAD 7130 Receiver, in mint condition, except for the audio output :(

    I really like this unit, wanted to always have one and I don't believe this issue to be serious.

    The unit powers up, however I don't hear a relay.. which I found to be curious as I don't see one either. All fuses on the main board appear to be good. All else, digital tuner board, and the other switching functions look great.
    There are jumpers and they all seem to be in the proper connectors.
    Not sure why there is no audio but an audible pulse is noted at the speakers at powering up leading me to believe the issue is not in the amplification circuit.

    Any assistance would be appreciated and speculation welcome :bigok:

    Thanks... AKers!
     
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  2. leesonic

    leesonic Hold on, here comes the bass. Subscriber

    Messages:
    4,666
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    It sounds obvious, but are the pre/power jumpers installed?

    Lee.
     
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  3. Dazaa

    Dazaa Super Member

    Messages:
    1,131
    Location:
    London England
    Tape monitor switch?
     
  4. 62vauxhall

    62vauxhall AK Subscriber Subscriber

    Messages:
    1,907
    That turn on thump would make me think the amplifier section functions. Have you tried headphones?

    Not your model but I made an attempt once to revive a 7240PE and believe I recall more fuses than I expected. A total of 6 I think and two of them were not in plain view.
     
  5. maxhifi

    maxhifi AK Subscriber Subscriber

    Messages:
    2,961
    Location:
    Edmonton Alberta Canada
    When I get an amp which presents as dead, the first thing I do is measure from the metal case of the TO-3 output transistors to the chassis, you should have your + and - rail voltages. Then check the bases for about (+-) 0.5-0.7V, and then check the emitters, they should be around zero. All good? check continuity between the emitter and the respective (+) speaker terminal, try the switches. If no, then the speaker protection relay or speaker selector is suspect.

    If that's all good, try an inject a signal at the power amp section input and see if you can pick it up at the speaker terminals. If yes than it's in the pre, if no, keep digging, etc.
     
  6. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
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    Thank you.. and yes, they are.
     

     

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  7. 50nstillhifi

    50nstillhifi Super Member

    Messages:
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    Thanks... will give that a go!
     
  8. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
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    Hmmmm.... I have located 4 fuses... but will search for others as well.
     
  9. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
    Carolinas
    No.... it was tried in both positions.. no change.
     
  10. trinhsman

    trinhsman AK Subscriber Subscriber

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    No expert here, but I had a Nad once and it had speaker buttons. Are they depressed? Tape monitor button? And lastly, as you have said you will look, hiding fuses.
     
  11. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
    Carolinas
    Yes.. thought the same, peculiar buttons.. but all are rotary or push, not difficult to be sure of the positioning.
    And the buttons were worked, back and forth, just in case.

    I am however going to try the headphones.. lacking a 1/4" adapter right now. This should validate the working amp section or not.
     

     

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  12. Dandy

    Dandy Super Member

    Messages:
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    Have you just tried the radio, or also an external input, e.g. CD? Do the tuner LEDs light up?

    Plugging in and out headphones might just free up the speaker switch.
     
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  13. pskaudio

    pskaudio No user serviceable parts inside me... Subscriber

    Messages:
    450
    Location:
    Delaware
    I picked up a 7140 with a similar issue. Turned out to be one of the preamp section's voltage regulators went bad. Hope this helps.
     
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  14. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
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    Gonna free up some time and get back into this NAD.. will let you know the results!
     
  15. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Messages:
    32,818
    Location:
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    Reminds me of a story. In my early days at AK, I came across a broken NAD receiver. It was (and mostly still is) over my head to diagnose and replace transistors and so forth. I offered it for free on AK and shipped it to someone on the West Coast. He wrote back and said there was a fuse on a circuit board inside that was blown, he replaced it and it fired right up. Dang it. :( I learned to at least take the covers off before putting a unit on the 'advanced repair' pile.
     
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  16. teal'c

    teal'c It's all moo Subscriber

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    On the plus side, you gave someone a scroe story.:thumbsup:
     
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  17. TomBig58

    TomBig58 AK Subscriber Subscriber

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    Luckily no issues with my 7130 yet. The previous owner said he had it serviced. A bit underpowered for most of my speakers but it performs very well as a pre-tuner. I really like it.
     
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  18. Dandy

    Dandy Super Member

    Messages:
    4,506
    Location:
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    Also, see if there is a signal from the preamp stage, by taking the output from the pre to another working power amp. (You have got more than one amp, haven't you?) ;)
     
  19. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,076
    Location:
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    Yes... I do Dandy! :rockon:

    And great troubleshooting technique.. will give it a go.. and post the result.
     
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  20. ConradH

    ConradH Addicted Member

    Messages:
    7,927
    Location:
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    Quick check- touch the pre-out/main-in jumpers with you finger. Do you hear a slight buzz? If not, power amp is probably down. Stupid thing, but be sure the speakers are wired correctly- this amp is horizontal (mine is vertical). This doesn't seem to have a relay, but it does have a circuit breaker on the output of each channel. No idea if they're reliable or go open. If you read the last couple threads on NAD, the switches can be very resistant to cleaning, and that will kill the output until they make contact.
     
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