Conference hips::uk_audioo

    Re:.0
    
    >The problem is the record deck (Technics) keeps losing one channel
    >every now and then. The amp (Rotel) must have some kind of extra
    >amp for the phono sockets, because if i changed the phono plugs
    >over to any other plugs, it comes out ok, but *very* faint.
    
    They *all* have that. Phono cartridges put out a very weak signal
    compared to a cassette deck, tuner or CD player. Some even have
    the choice between MC and MM cartridge inputs. (A few quick figures:
    MC cartridge puts out 0,1 mV, MM puts out 1 mV and line levels for
    tuner and CD are 100mV up to 1V, just to get you in the ballpark.
    Standard phono inputs are almost always MM)
    
    >From this way i have determined that it must be the amp sockets
    >that are dodgy.                          
    
    Maybe. What happens when you move the LINE OUT cables from the deck
    to another input, say Tuner or Aux? What happens when you fiddle
    the tape monitor switch or the input select switch? Just move it
    a bit, not so much to move it to another selection. If you hear
    crackling or grating noises from the speakers when you do that,
    the switch is dirty or bad. VOLUME DOWN!!! And what about the cables?
    Do they have plugs on both ends so you can change them for another
    pair? (I've seen Techies with cables fixed to the deck, no plug
    on that side.) Does the channel drop when you play records? Apparently
    not, otherwise you'd have said so. 
    
    Instead of flicking the power switch, which isn't that good anyway,
    try tapping near plugs and switches until the sound comes back.
    Not too hard, you want to determine where a fault is and if you
    rock the whole amp like a San Andreas hiccup, you'll never know
    the problem spot.
    
    Let me know and good luck.
    
                                                - Rik -
     
         
    

    You can also go into an electronics store or ask a nearby tech and
    get a can of contact cleaner. Open up the amp and spray the switches
    and controls (It's old you said? Warranty void, naaaah, no problem
    there). If you really want to get daring, look for bad wire
    connections; wiggle them a bit and see if the problem goes away
    or gets worse. Get the plug out of the A(aaarrgh)C socket while
    your fingers are inside the amp ....
    
                                                 - Rik -

    rik,
    
    thanks for input. The record deck makes a sort of humming noise
    when no record is playing and it only loses its channel when a record
    is playing.
    
    i think that it is not grounded properly (the humming), and this
    stops as soon as you place the 'needle on the record'.
    
    i'll open it up tonight and have a peek.
    
    lewis.

    Oops, misinterpretation. I read your base note as if you were talking
    about a record player plus a cassette deck (plus amp) setup. .3
    brought the enlightenment.
    
    Could be several other things now: those Technics record players
    (model? cartridge? is it automatic?) sometimes have a switch between
    the cartridge and the outgoing cables. Sounds like something could
    be wrong there. Also most record players NEED a separate ground
    cable from the player chassis to the amp chassis; there is a separate
    wire next to the signal cables and a small ground clamp/screw near
    the phono inputs on the amp. This will stop the humming. The losing
    of a channel (and subsequently resetting by rebooting the amp) is
    more likely than not originating in the phono preamp. There are
    several scenarios how this happens, it depends on the design so
    I can't give you a definite clue, but try pushing and moving the 
    components lightly. Also ask the same tech from .1 for a can of
    freezer spray (decide for yourself in the matter of amp vs. ozone
    layer), and try chilling each component in the phono preamp. To
    make life easier, most Japanese amps have a kind of block structure
    silk-screened on the print, e.g. tone control, phono preamp. 
    
    Again, good luck.
                                                       - Rik -
    
    PS. This is the other way around: normally I'm getting remote diagnosis
    assistance from the south of France and then I'm supposed to fix
    it..... 
    

    re; -1
    
    Thanks, will try this also.
    
    P.S. I wish i was in the south of france!

    Actions on next wakeup (to be performed daily):
    
    1) Do full brain test.
    
    2) Replete with coffee.
    
    3) Connect brain to fingers before entering notes, especially before
       - associating 'deck' with 'cassette'
       - associating 'France' with 'south of'
    
    
                                   - Rik - (somewhere north of France)
    
    
    
    P.S. You ARE in France or did I misread .0 entirely???

    I am in france. I'm near Geneva.
    
    Not in Valbonne. La de da de da...

    How are things working out?
    
    Now that I've come back from holiday to read .7 and realise that
    I could have given you a hand in repairing without stretching my
    arm too much. (Been skiing, stayed with a friend in Geneva for a
    few days)
    
                                                 - Rik -

    Well Rik,
    
    To be quite honest, i havent really done much with it. It wasn't
    happening that much recently so i left it. But now i've been moving
    and havent had time to play around with it.
    
    When i've get it set up again, i'll try again and keep you posted.
    
    Cheers,
    
    Lewis.