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One channel does not worked on first switch

Discussion in 'audio' started by gints, Oct 8, 2019.

  1. gints

    gints pfm Member

    I have a question for technical people.
    Got new amplifier, Denon 2500, and at first switch on right channel did not work or worked for few seconds and then silence. Not sure about that. Switched off amp, switched on still no sound, disconnected speaker, connected back, sound was for a couple second and silence again. Amp off ,amp on, speaker off, on. After several attempts everything started to work fine. Speakers are over ten years old, was not played for a month. I need to know can this be speaker related, something with crossover, or amplifier is only possibility? If amp, is it some hidden fault or can be explained by not using it for some period? I once some time ago bought used bluray player it has similar situation. One channel did not work at first switch. Came alive after some time and was ok since.
     
  2. manicatel

    manicatel pfm Member

    Switch the speakers over, L-R & R-L. Does the fault still happen on the right?
    If so, it’s probably the amp. The Denon 2500 is not a new amp is it? I think it was a 2018 model but it should be under warranty so it may have to go back to the dealer.
     
  3. gints

    gints pfm Member

    Fault already gone, I cannot repeat it now. It come alive before I had a chance to switch channels at speakers. I did it with input, tried other inputs, no change at the time.
    It suppose to be new, box not very fresh, but everything else looks like new. Yes, It may go back, but it is online sale, overseas delivery, a bit hassle, I would like to avoid it if possible.
     
  4. gints

    gints pfm Member

    Is is something what can be checked at service centre or they also will be looking into dark as there is actually no fault at the moment.
     
  5. booja30

    booja30 pfm Member

    Why don't you switch your speakers now so that if it happens again you'll have more data? E.g. if you switch the speakers and it happens momentarily in the future you can either rule out the speakers or the amp.
     
  6. gints

    gints pfm Member

    At the moment there is new speakers connected, so speaker will be ruled out.
    I tried with old ones, they fine now.
     
  7. eddie pugh

    eddie pugh pfm Member

    Lazy muting relay on the Denon ?

    eddie
     
  8. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Protection relay quite likely.
     
    Wilson likes this.
  9. gints

    gints pfm Member

    Does that protection relay working without clicking sound? I did not notice any associated sound in amp when sound in speakers came and go.
     
  10. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Usually there is an audible click yes but sometimes the click is very quiet. Both channels would be off until the click. There's many issues which could cause your problem... the symptoms were such that dirty contacts on protection relay would be my first guess but of course not all amps even have a protection relay.
     
  11. gints

    gints pfm Member

    Other channel was fine all time. Main question is, can it give me trouble in future or affect sound quality? And there is nothing in speaker what can give that kind of fault?
     
  12. eddie pugh

    eddie pugh pfm Member

    On my Technics SL10 auto linear tracking turntable there is a muting relay that basically connects the signal to ground until the cartridge is safely landed on the LP It should then unlatch and allow the signal through to the phono out. The relay has been acting up lately and only unlatching one channel which results in one channel remaining mute

    The relay is a sealed reed relay and no longer available but I'm sure I could bodge a solution using a standard low signal relay

    eddie
     
  13. gints

    gints pfm Member

    Was playing bit more music today, moving new speakers, and notice that I cannot get proper centre image. Started to look into and at low level right channel is much quieter, with louder level difference is less, still can be noticeable. Not usable for late night listening.
    I connected Tisbury pre to amp's ext input, balance was good even with first click on Tisbury volume pot. Channel unbalance started to be less obvious with sound level which is about the same as with Tisbury pot on 7-8 click. So it must be volume pot? Can volume pot be responsible for right channel not working at first or that is not related at all?
     
  14. booja30

    booja30 pfm Member

    Yeah, especially if it's dirty inside. But I'm surprised a new high end Denon have such a cheap potentiometer that would do that. So maybe, maybe not.

    Does it crackle at all if you wiggle the knob around the lowest levels?
     
  15. gints

    gints pfm Member

    No, it is quiet.
     
  16. gints

    gints pfm Member

    Do not know how much is bypassed using ext pre input on amplifier. Is it only volume pot or is there much more of preamp circuit involved where can be hidden fault? I think it is good enough reason to ask for replacement.
     
  17. gints

    gints pfm Member

    Today connected my old speaker to old amplifier. The same right speaker stopped to work at middle of song. Opened terminal block. Looks that there was done some modifications, very bad soldering job, loose contact at terminal. Have to look into speaker more to see what else is done and what is a quality of work. I think now I can rule out amplifiers fault. What is this thing when fault reveals itself at the most inappropriate moment?

    Put back new amp to new speakers. From cold balance looks fine. I confused. Will see what it will do later. Is there possibility for drift?
     

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