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Potential Naim NAC52 fault

Discussion in 'audio' started by Soundwave, Sep 16, 2022.

  1. Soundwave

    Soundwave pfm Member

    Hi there was hoping someone might be able to help with an issue whilst I’m waiting for Witchhat to get back to me.

    Had 52 serviced by Witchhat a few months ago, on its return It was unboxed and setup but just sat powered up muted and not used due to a new baby and other stuff getting in the way of listening. Anyway, finally got an hour to myself yesterday and noticed an issue. With no source playing and volume at zero, when you turn the balance you get horrible sound similar to when you clean your stylus with some volume and the speakers move in and out an alarming amount just on one channel. This happens at higher volumes too, and still only on one speaker. Weirdly as the balance goes fully to the other clean speaker, you still get the distortion on the faulty channel, but music only comes out the good channel as you’d expect from a fully turned balance pot.
    The volume pot is also making a quieter similar sound on one channel and I have heard random static type pops and clicks.
    If you play some music it comes through clear on both channels with no added fuzz.
    I have double checked all connections and also swapped the 135’s around & speaker inputs to eliminate those 2 areas but the issue just changes from left to right as expected, so think those areas are good.
    Is there anything else I can do to see what is at fault? Just leaves the 52 or my supercap as suspects which was serviced by Naim about 3 years ago. Bit puzzled as surely service would have noticed faulty pots and coming only from 1 channel is kinda odd. It certainly wasn’t doing this pre service. Any advice gladly taken whilst I wait for a reply.
     
  2. NickofWimbledon

    NickofWimbledon pfm Member

    I had a weird issue with my 52 when plugging things together recently - one channel gone and no Aux 2 power to the Superline, plus what sounded like a dirty connection on the functional channel. While I was trying not to over-react, Simon at Infidelity suggested I swap Burndies (I too have WH cables and have been swapping Naim to WH for comparison). All problems magically vanished. My Naim burndy must be 30 years old anyway...

    Before sending the 52 back to WH and being without if for some time, can you try swapping burndies?
     
  3. Paul Hindle

    Paul Hindle Do you mock me?

    If you have the original grey Burndy that would be the chief suspect. Mine was falling apart before I replaced it with a Hatpin.
     
    NickofWimbledon likes this.
  4. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Sounds like a leaky cap (prob a tantalum) putting DC on the pots.
     
    MJS likes this.
  5. Mr Pig

    Mr Pig Trade: ^'- -'^

    Sounds like the pots need cleaned. As they get old it happens and cleaning them is only a temporary fix. Spin the knobs a bit. If the noise gets better or goes away, that's what it is.
     
    NickofWimbledon likes this.
  6. Soundwave

    Soundwave pfm Member

    Thanks for the replies all. WH have arranged for it to go back now along with SC and Burndy so they they can replicate the problem exactly. Their engineer suggested tants so we shall see. Thought that was a normal service item so bit annoyed at this tbh so hopefully it does not cost me anything.
    I only have the one burndy cable so can’t try a swap
    I did try winding the dials fully a few times on several occasions but to no avail. Loathed to put any cleaner on them as it’s a warranty job.
    Is it normal to hear the noises in the silenced channel when balance fully over to the good channel? That’s what threw me. Thought it would go quiet.
     
    NickofWimbledon likes this.
  7. NickofWimbledon

    NickofWimbledon pfm Member

    I am sure WH will sort you out, though you may need to keep calling them to get things done as fast as you would like. Good luck!
     
  8. Soundwave

    Soundwave pfm Member

    Just heard back from WH. Had a failed Tantalum cap so all fixed and on its way back to me. Not sure if this was one that was changed during service or an existing one that had gone pop. Anyway hopefully I will be a happy customer now.
     
  9. nobeone

    nobeone Total Member

    I imagine they replace all tants in a service, I suspect you got unlucky with an early failure on a new tant. Bathtub curve stuff, some fail quite quickly, then they will last well, then they start failing again. A soak test catches most early failures but ... there is only so long you can soak stuff for before you have to assume all is ok. Then you get to enjoy it for a decade or two, then it may need a service before age starts killing them again. Hope it all goes well from here and full marks to @Arkless Electronics for the experienced early call.
     
    Arkless Electronics likes this.
  10. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Or a new tantalum had accidentally been fitted the wrong way round...
     
    nobeone likes this.
  11. MJS

    MJS Technical Tinkerer

    Unlikely, JJ will have done thousands in his time and knows exactly which way round they go. Unfortunately the preamps aren't as good as the power supplies at letting you know when they're leaky or badly orientated. Turning on a brand new CDS on test with 84 of the bastards was always a lottery.
     
    nobeone likes this.
  12. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Maybe a more junior staff member did it.... dunno... anyone can make a mistake even if very rarely... or of course a "Monday morning/Friday afternoon made" cap just packing in for no apparent reason. It does happen now and then with any and all components.

    There's really no place for tantalums in audio.
     
    nobeone likes this.
  13. nobeone

    nobeone Total Member

    It was the scorch marks up the wall from a big old PSU cap that was back to front that I remember most ... tants are, I feel, part of the Naim sound ... whether you like it (many do) or not (many don't, I know which camp you are in Arkless!).
     
    Arkless Electronics likes this.
  14. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Tants generate more distortion than any other type of cap. They were a fad back around ... oh well about when Naim started out actually:D
     
    nobeone and Paul Hindle like this.
  15. MJS

    MJS Technical Tinkerer

    That was a Hicap with the reservoir caps back to front. The transformer happily supplied all the current needed to boil off the electrolyte, and boom. Made quite a mess that one - I was there when it happened. The cap manufacturers had changed the orientation of the vent cap, and the wiring team always used them as a reference :rolleyes:. Naturally, instead of re-training everyone to use the + and - markings they chose to black-out the vent caps and paint new dots on where they used to be. I am not making this up.
     
    Arkless Electronics and nobeone like this.
  16. Mozart

    Mozart Active Member

    What do Tantalum caps sound like?
    What do other caps sound like?
    Intriguing, I know nothing about this stuff.
     
  17. Paul Hindle

    Paul Hindle Do you mock me?

    I used to put caps in a toy gun when I was a kid. They went bang. They also worked whichever way round you installed them. Naim are obviously asking for trouble if you ask me.
     

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