Dang -- my "Simple 2A3" amplifier. Just. Blew. Up.

mhardy6647mhardy6647 Posts: 14,340
For an as-yet unknown reason, the cathode capacitor on one channel of my (slightly modified) JE Labs "Simple 2A3" amplifier variant just self-immolated.
Big ol' pop.
Magic smoke.
Acridity.

Fug.

I am wondering if one of them big ol' Sofia "meshplate" 2A3s suffered a filament short... or just what the dang deal was.

Funny thing -- I thought that the other channel was lower in volume, and I was troubleshooting that when the fun began... but maybe the soon-to-immolate channel was actually higher in volume(?!?).

Fortunately, we do still have SE 2A3 backup at the ol' casa.

Paramours are go!

9835310896_f77fa68f7c_b.jpgDSC_0105 by Mark Hardy, on Flickr
(photo from a long time ago...)

Thanks for letting me -- ahem -- vent

PS - I did not try the Sofias in the Paramours :neutral: Tossed a pair of cheap-Jack "ValveArt" 2A3s in 'em. For now.
"Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

Comments

  • msgmsg Posts: 3,143
    Dislike.
    Yet, like.
  • mhardy6647mhardy6647 Posts: 14,340
    as an aside - it was the low-volume channel that popped a capacitor; I forgot I was lookin' at it upside-down! I am not too good with spatial stuff.
    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

  • bikerboybikerboy Posts: 1,059
    Led Zep will do that!
    D:UltraRendu usb w/LPS-1->Amanero I2S converter ->I2S->TPA Buffalo III dac w Salas ps->BAT VK-51SE w/BP Preamp via XLR to Parasound A-21-> SDA-2.3 w/ RDO, Soniccrafts caps, Larry's Rings;
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    :
    V:Vinyl rips-> ESI Juli@24/192
    SACD: Denon 3910 via I2S.
  • DSkipDSkip Posts: 13,202
    Simple is as simple does.
    audiothesis.com/

    Speakers: Usher: CP-6311, Be-10, T-515; Rosso Fiorentino: Elba, Fiesole, Volterra, Polk: T50, Signature S60, S55, S35, S30, S20, S15, RTA 15tl, Sonner Audio Allegro Unum
    Preamps: Shuguang S200MK, Dayens Ampino, Parasound P5
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    Cabling: Wireworld
    TV: Sony XBR-75X940C
  • agfrostagfrost Posts: 1,906
    Hope you get it sorted out, Mark.
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Marantz DV-9500 * Modded Adcom GDA-600 DAC
    Micro Seiki DQ-50 * A hodgepodge of cabling * Belkin PF60
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  • rednedtugentrednedtugent Posts: 10,282
    :o
    That is why you need backup SS equipment o:)
  • mhardy6647mhardy6647 Posts: 14,340
    :o
    That is why you need backup SS equipment o:)

    ummm...

    24708700600_ce3816961b_b.jpg010 by Mark Hardy, on Flickr

    ;)

    The most likely "root cause", I reckon, is that the output tube on that channel shorted. I am frustrated because I don't have any means to test a 2A3 :( -- other than use test (i.e., plug it in another amp and see if something blows up). A shorted output transoformer's another potential cause.

    I can replace the cap and start checking voltages (with no 2A3s installed).

    It just wasn't something I was expecting to be worrying about this week :neutral:
    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

  • rednedtugentrednedtugent Posts: 10,282
    sorry man :(
  • mhardy6647mhardy6647 Posts: 14,340
    Well, the tubes have plenty of miles on 'em... and the caps per se are no problem to replace.
    I am just not looking forward to troubleshooting :#

    The oogy stuff from inside the eviscerated cap dissolved some of the print off the bottom terminal panel of the OPT on that side. Fortunately the other one's still legible.
    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

  • EndersShadowEndersShadow Posts: 14,456
    First world problems.... just roll in another amp and put that one to the side till you feel like troubleshooting lol....

    The audio gods are saying, time to play with some other amps that haven't had any love in a while.
    Advice is free, the Flea Market is earned - F1Nut

    Lessons cost money, good ones cost LOTS - Tony Beets

    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)

    My system makes me happy and changes too often for me to care to update a list..... you guys are good at spending my money!
  • mhardy6647mhardy6647 Posts: 14,340
    Affirmative, Houston. Chinese 2A3s -- but relatively good ones (the TJ/Sophia "meshplates"), as such things go.

    16187805777_019bdb6d9f_b.jpgDSC_0128 by Mark Hardy, on Flickr

    Affirmative, Houston, backup amps (and tubes) are installed and on-line.

    :)

    35012452392_88f03899cc_b.jpgDSC_8376 (2) by Mark Hardy, on Flickr


    FWIW. Here's a forensic photo of the accident scene. Trigger warning - not for the squeamish.

    35011906962_64b4e0d2ff_b.jpgSimple 2A3 after the fire 08Jun17 by Mark Hardy, on Flickr
    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

  • mhardy6647mhardy6647 Posts: 14,340
    I couldn't measure the DC resistance of either 2A3 (i.e., they're both at the residual level of the DMM I used, 0.3 ohm) -- so I cannot tell if one is different than the other (i.e., shorted). I don't (hard to believe though it may seem) have a tube tester that can check a 2A3!

    On the bright side, the DCR of both OPT primaries is (are?) identical: 157 ohm. The OPTs seem to be OK.

    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

  • tonybtonyb Posts: 27,357
    Just goes to show...your never too old to blow stuff up. lol
    legacy Focus 20/20
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  • ALL212ALL212 Posts: 583
    edited June 8
    Well...after looking the picture over it's quite obvious what the issue is here.

    Looks like you used a #4 star washer instead of a #6. Your flummox adapter's are both backwards and you didn't rosin up your bow.
    Aaron
  • pitdogg2pitdogg2 Posts: 7,060
    yuuup^^^^ you nailed by jimminy
  • mhardy6647mhardy6647 Posts: 14,340
    youse guyses is good
    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

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