Rotel RB971 Fault

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by AdrianH, Aug 27, 2006.

  1. AdrianH

    AdrianH
    Standard Member

    Joined:
    Nov 20, 2005
    Messages:
    97
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Ratings:
    +2
    Hi,

    I have an issue where I have just sold a Rotel RB971 mk2 set to Bridged Mono mode and was working perfectly in my set up before despatch to it's new owner. Unfortunately when the buyer fired it up at his end and 'ear splitting hum' was emitted from the speakers.

    Has anyone any ideas what could have happened here?
     
  2. sdb123

    sdb123
    Distinguished Member

    Joined:
    May 17, 2005
    Messages:
    18,182
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Rushden, Northants
    Ratings:
    +2,252
    I take it that the 971 is a power amp....is the new owner running directly into it instead of through a pre-amp?
     
  3. chachi

    chachi
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Perhaps one of the bridging jumpers popped off internally in shipment (?)
     
  4. AdrianH

    AdrianH
    Standard Member

    Joined:
    Nov 20, 2005
    Messages:
    97
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Ratings:
    +2
    RB971 is a power amp, and yes the new owner is running through a Pre-Amp, I am getting the Amp sent back so will check the jumpers when I recieve (must admit this was one of my thoughts).

    Should get it back about mid-week so will keep you updated on my findings....

    Cheers
     
  5. chachi

    chachi
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Perhaps he didn't wire it up properly to the 'outside' posts ...
     
  6. AdrianH

    AdrianH
    Standard Member

    Joined:
    Nov 20, 2005
    Messages:
    97
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Ratings:
    +2
    Hi guys,

    Just got the amp back and checked out jumpers (ok) and made sure it is correctly wired up and yes we do get this 'mains hum'. I have just had a look round inside and everything seems to be ok, I am at a loss as to how something like this happens in transit as it looks virtually bomb proof?

    Any suggestions or recommendations of a good repair shop around the Derby area?

    Many thanks
     
  7. AdrianH

    AdrianH
    Standard Member

    Joined:
    Nov 20, 2005
    Messages:
    97
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Ratings:
    +2
    I've just put back to stereo mode by moving jumpers back to 'factory settings' and was about to hook up to my processor and wondered if there is a possibility of doing some damage to the processor/speakers - any feedback would be most gratefully received.

    Cheers
     
  8. morksbeanbag

    morksbeanbag
    Active Member

    Joined:
    Jul 25, 2004
    Messages:
    723
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Chesterfield, Derbyshire.
    Ratings:
    +49
    Doubt you could damage the processor, but don't use your best speakers, find something cheap to use as a test.
     
  9. chachi

    chachi
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    In addition to using cheap speakers, have you got an old VCR or cassette deck lying about for a direct source?

    Wouldn't use/risk a processor or 'good speakers' for this IIWIYS ...
     
  10. AdrianH

    AdrianH
    Standard Member

    Joined:
    Nov 20, 2005
    Messages:
    97
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Ratings:
    +2
    Did that in the end and the amp worked fine so hooked up to 'good' speakers/source and RB03 and it worked fine again (and sounded better ;) )! :thumbsup: ran it for two hours without a hitch so swopped jumpers to mono format and that went ok also!

    So all in all a good result - my guess is that the guy must have had a short on his speaker connection giving the 'hum' - thing is it cost me a sale and a fair few bob on paypal/ebay charges.....

    Many thanks for all your help - just about to post next query on my new 1066/1075 combo!

    AdrianH
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice