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Naim Nap 135 Servicing thread

Discussion in 'reference' started by colasblue, Nov 23, 2014.

  1. colasblue

    colasblue pfm Member

    If you really must squeeze two 47uF tants into one pair of holes the best way to go about it is to scrape down the legs of the tants with a craft knife until they'll go in rather than try to enlarge the hole.

    An alternative and perfectly satisfactory approach is just to solder one in and leave the legs a bit long and then solder the other across the legs on the "dark side" of the board.

    I built my 160 clone that way.
  2. S_J

    S_J pfm Member

    Some modern tantalums (AVX for sure, maybe others) don't have particularly thick legs anyway, and the Naim holes are a bit bigger than they need to be. I've found in the past that two 47uF tants can fit into a single pair of Naim holes with no faff involved. Pre-bend the legs so that they sprout out of the circuit board and neatly branch out to each tant, don't stuff the tants down and tight together in the hope of keeping the legs as short as possible, that might put some stress on the legs/joints.
  3. juz400

    juz400 pfm Member

    I took alot of pics with my crappy camera, appologies as this was the best.

    Its a NAPA6-4 Board I purchased from this parish a few months back.
    I have marked the Tants as I can see them with a magnifying glass


    Im guessing that these are original STC mentioned by Colasblue as they dont look like the nice new AVX ones I have to go in.
    Also mentioned in this thread are caps mounted incorrectly
    Can anyone confirm I have the correct polaritys marked
  4. colasblue

    colasblue pfm Member

    That's actually a fairly late board revision to have those two 47uF caps in parallel and in their own holes.

    It may just about be new enough to have had yellow Kemets fitted as original equipment, they certainly aren't STC.

    OTOH somebody may have already changed them.

    The polarities you have indicated are all correct.
  5. juz400

    juz400 pfm Member

    They could possibly be AVX, the body and text the same colour, both say 106 and 35+ for the 10uF
    My new ones have that inverted L over the text as the installed ones dont.
    Good News that the polarity are correct, I guess it only adds to this thread in a positive way! :)
    Time to get the olde Weller warmed up!
    Thank you for your help and confirmation.
    (Im looking forward to New Years Eve to really try these out! 500VA, HackerCap and a 12" Bass driver each)
  6. colasblue

    colasblue pfm Member

    New bit on alignment added
  7. geoturbo

    geoturbo pfm Member

    Hello guys,
    not trying to hijack the post (moderators may move and open a New thread..) however quoting Matt reply due to am finding 100uF 16v tant in my 135s at feedback position..
    unofficial service made more than 5 years ago.. and hearing a crackling and hum in both my speakers.. am thinking to go for double 47uF MMK each to ser how they behave and if cure to crackling is round..
    Any hint by the experts will be welcome..

    Very good Colasblue by the way, Thanks a lot for sharing,
  8. MJS

    MJS Trade: Consultant at WH Audio

    Crackling is never the feedback cap, it's always the 10uF/63v axials on the power supply board.
  9. geoturbo

    geoturbo pfm Member

    Thank you Mark will surely give it a try
  10. geoturbo

    geoturbo pfm Member

    Cap swap done,
    just turned on the thing and scratching disappeared! (thanks a lot Mark. 50Hz hum remains in the speakers but this is for another story, not really a hum.. it sounds like a tictic @ 50Hz frequency).
    Hopefully will be able to make some serious listening soon.

    Oddly enough the scratching from the other channel/135 in the speakers disappeared too.
    Will of course substitute 10uF Pana NHG electrolytic caps on regulator boards of the other 135 as well, soon.
    I had some 47uf Elna Silmic II to try too and changed these as well.. would like to post the picture.. soon..

    Trimmers of this channel1 135 being oversensitive and not easy to set.. but eventually set Naps voltage @ +40.0V -40.6V, Napa bias @ 7.0mV.

    Having a very smooth pop from the speakers when turning on this channel1 135.

    Not having a pro multimeter indeed.. but measured DC Offset of 6.0mV (DC) and 1.2mV (AC).

    I am wondering if the 50Hz hum I am hearing in the speakers is now due to the measured 1.2mV AC voltage. Could it be due to this "small" AC voltage?
  11. Pete MB&D

    Pete MB&D Pete Maddex, the one and only!

    Some one said you can get a hum if the wires to the thermal trip aren’t flat to the bottom of the case.

  12. geoturbo

    geoturbo pfm Member

    Thank you for asking me to double-check, Pete.
    Assuming you mean the 2 long yellow wires, checked back and they are running flat to the bottom in both amps.

    The channel2 135 underwent the same above treatment now, with the scratching already solved from channel1 (!!!).
    Measured a DC Offset of 15.2mV (DC) and 2.2mV (AC).

    I plugged the hifi ac power distributor onto a different plug in the wall (now 10A only..) and most of hum in the speakers is gone (!!!).
    Still some other noise to be improved (a 50Hz tictic) but will leave it for another story (very likely coming from the modded pre 32-5+Snaps), and dreaming of a dedicated mains line..
  13. martin clark

    martin clark pinko bodger

    (added 28.6.19)

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