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

mhardy6647mhardy6647 Posts: 13,889
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.

Comments

  • msgmsg Posts: 2,852
    Dislike.
    Yet, like.
  • mhardy6647mhardy6647 Posts: 13,889
    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.
  • bikerboybikerboy Posts: 1,058
    Led Zep will do that!
  • DSkipDSkip Posts: 12,901
    Simple is as simple does.
  • agfrostagfrost Posts: 1,877
    Hope you get it sorted out, Mark.
  • rednedtugentrednedtugent Posts: 9,865
    :o
    That is why you need backup SS equipment o:)
  • mhardy6647mhardy6647 Posts: 13,889
    :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:
  • rednedtugentrednedtugent Posts: 9,865
    sorry man :(
  • mhardy6647mhardy6647 Posts: 13,889
    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.
  • EndersShadowEndersShadow Posts: 14,192
    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.
  • mhardy6647 wrote: »
    :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:

    It is stuff like this that, when NASA asked me to be the lead Cosmo-naught on the first trip to Mars, caused me to say no. I'll let Tom Hanks be first. And when his cell phone battery pukes 10,000 light years from earth I get to say, "See, I told you so." Until "they" figure out how to defeat the Peter Principle (and we all know who "They" is) I'm staying in my Tacoma WA bunker. It looks like you do have backup systems for your Mothership, always a wise move. Are those Chinese tubes?
  • mhardy6647mhardy6647 Posts: 13,889
    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
  • mhardy6647mhardy6647 Posts: 13,889
    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.

  • After you cover your $25,000 deductible, you're insurance company should be good for the rest. You're in "Good Hands." :)
  • tonybtonyb Posts: 27,202
    Just goes to show...your never too old to blow stuff up. lol
  • ALL212ALL212 Posts: 570
    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.
  • pitdogg2pitdogg2 Posts: 6,565
    yuuup^^^^ you nailed by jimminy
  • mhardy6647mhardy6647 Posts: 13,889
    youse guyses is good
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