5e3 static issue

Discussion in 'Amp Tech Center' started by Q tip, Nov 17, 2019.

  1. muchxs

    muchxs Doctor of Teleocity

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    IMO your tech is a (fuzzy little kitty cat). I barely need to take my socks off to count the parts inside one of these. "Could cost a ton of money to troubleshoot?" What a schnozzle!

    I have no difficulty killing EH tubes or similar "Tung-Sol" reissues. It ain't 1965 anymore. Russian tubes sure ain't RCA or Sylvania.

    Going around in circles. Schnozzle tech already passed on it and handed it back to the customer.


    I'll take a WAG: A zorched "Tung-Sol" 6V6 gave the cathode bypass cap a blast of high voltage. The cap isn't designed to endure 300- plus volts.

    Seems like the heroic little cathode cap re- formed when its environment returned to more or less normal.

    The circuit will function with the bypass cap entirely removed. It may function better with a new one in its place.
     
    Last edited: Nov 24, 2019
  2. The Ballzz

    The Ballzz Tele-Afflicted

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    @Q tip

    ^^^^ What He Said! ^^^^

    Additionally, that cap should be cheap/easy to replace. I'd sure love to see a gut shot of this amp, as I've never seen one of this particular model!

    Thanks & Best Of Luck To Ya!
    Gene
     
  3. Q tip

    Q tip TDPRI Member

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    If I understand you correctly you are saying I can just pull C10 and put nothing there and see if the noise is gone?
    Thank you for responding.
     
  4. Q tip

    Q tip TDPRI Member

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    I'll post some gut shots later today for you.
     
  5. muchxs

    muchxs Doctor of Teleocity

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    Yeah, your 5E3 will function with C10 removed. Just don't goober the solder joint(s) while you're there. You may get rid of one source of crackle and cause another.

    Nichicon just upgraded their 50v caps. The old 22uf @ 50v is now 22uf @ 63v, slightly more durable than the old 50v. 47uf @ 63v would work well, too.
     
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  6. elpico

    elpico Tele-Holic

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    Okay I misunderstood. It's fine to run it with C10 disconnected, I'd try that next.

    I don't know any techs here unfortunately. My grandfather was army signal corp and general mr fix-it on base through the 50s and 60s so he was an expert with tubes. He was my tech and amp builder when I was growing up. Then over the years I learned electronics too and worked in that field for many years so I haven't needed a tech in town.

    There's a few more things you can try here, but if it remains stubborn I could take a look for you. I'm in Mt Pleasant
     
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  7. Q tip

    Q tip TDPRI Member

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    This is great, I will try this today. Elpico also mentioned C10 as a possible culprit. Seeing as I don't have these caps on hand it's great that I don't need one to test this out.
    Thanks a lot.
     
  8. Q tip

    Q tip TDPRI Member

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    Hey thanks so much Elpico. I'll see how this goes and post my results.
     
  9. Q tip

    Q tip TDPRI Member

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    Heres the gut shots I promised. Getting to that cap now. IMG-0050.jpg IMG-0054.jpg
     
  10. Q tip

    Q tip TDPRI Member

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    So I tried to pull that cathode cap c10 and tugged pretty hard but I could not get it to budge at either end. Might it be wrapped around the other wires on the other side or is it better to just clip it leaving enough wire to join a new one or rejoining the old one if that is not the problem?
    Any tips on removing that cap?
     
  11. The Ballzz

    The Ballzz Tele-Afflicted

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    @Q tip
    I Hate tag boards! :(

    Yeah, it's ugly, you aren't going to love it. Best is to pull up the tag board, to get to its other side! Or the other "ugly" way of leaving long leads. :rolleyes:

    Did I happen to mention that I hate tag boards?

    On another note, that chassis certainly appears to have gotten bounced around a bit in its life? I am however impressed by the old school, hand wired construction of such a modern release/semi-production model amplifier. And thanks for the pics, they gave me a clearer idea of what you were working with. I kinda half expected a PCB! :eek:

    I hope you get it worked out, as these are absolutely glorious amps!

    Just My $.02,
    Gene
     
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  12. Q tip

    Q tip TDPRI Member

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    Crap that sounds like a lot of dismantling. I'll have to really think about this.
    The chassis hasn't been mishandled and is like new but it's probably the foamy insulation that lines the chassis edge that makes it appear as though the chassis is bent but it's not. I think the foam is there to keep the rear baffle board from vibrating.
    Yeah I've got a 12ay7 in V1 and a 5751 in V2 which is really sounding nice. I'm really enjoying this amp a lot with the exception of this crackle issue. It's really nice on my tired ears and the 5751 brought out some clarity which is odd to me because in everything else I tried it in it sounds a bit dark. Not in this amp though. Maybe the lesser output in this circuit gets a different result.
    Thanks for the pull the tag board tip. I was afraid that may be the case.
     
  13. The Ballzz

    The Ballzz Tele-Afflicted

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    Leaving long leads isn't necessarily a mortal sin. You're the only one who knows and it can certainly get done in a manner that is well roadworthy. That particular cap is one that often gets monkeyed with to make some subtle changes to the amp. You may want to do a little research, maybe even over at the Rob Robinette site. It may not be a bad thing to have that particular cap laid out as a "Quick Change" until you either get your problem tracked or just want to try different bias cap values.

    Enjoy,
    Gene
     
  14. Q tip

    Q tip TDPRI Member

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    OK that is another approach that might make sense to try. I will have to do some soul searching on this issue but realizing the problem quickly is the main goal at this point I think.
    Thank you.
     
  15. Q tip

    Q tip TDPRI Member

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    Well, I'm back. Sorry for the long break.
    I was waiting to get a 5y3 then realized I could just take the one out of my deluxe and see if it made noise in my Creama Wheat. It worked fine so that eliminated the rec. tube.
    I started to touch up all the solder points and did most of the caps in the output section. I tried the amp and it was quiet and clear for a couple of hours then the static came back but this time primarily when I played through the amp as opposed to willy nilly.
    I went back to better resolder one of the caps I had already touched up and had to remove the 2 volume and 1tone pot. When I turned the amp back on the noise was still there when I played. I reattached the pots securely without the knobs but and noticed when I swipe the tone pot with my finger that I get crackle and if I hold it I get some hum also.
    There is no noise when I turn the pot(which I cleaned prior anyway). *I get continuity to ground as I should on all pots.
    Is it possible that something in that pot is causing this?
     
  16. Lowerleftcoast

    Lowerleftcoast Tele-Meister

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    Did you replace C10?

    Just went thru the thread. I noticed you did not cold spray C11. C11 is past the P/I. (it is also near the tone pot)

    A friend just built a train wreck. Had crackle. Turned out to be a filter cap. Chop sticked when hot. Found it. YMMV.
     
    Last edited: Jan 23, 2020 at 9:19 PM
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  17. Q tip

    Q tip TDPRI Member

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    I haven't replaced any caps or resistors to this point but I did spray C11. I think I am at the point of replacing the filter caps and C10 also. I have to order the parts which I think I will do today.
    Thanks for your post as I was on the fence a little about ordering the replacement caps but at this point it would be nice to at least remove those from the equation as I've done most everything else I can think of.
     
  18. Lowerleftcoast

    Lowerleftcoast Tele-Meister

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    I think Muchxs was on point. C10 could very well have been damaged when the tube red plated.

    Your local electronics store should have this value on hand. 25uF@50v or upgrade to 47uF@63v even 100v would be fine. It may come in a radial can but you can make it fit. If you want a prettier one just tack this one in and install the prettier one at a later date.

    Clip the old one out leaving enough lead to tack in the new one. Mind the polarity. (+) towards the tubes. (-) towards the volume pot. The amp will work without this cap. The cap helps to add volume and bass.

    If c10 does not cure the static, most likely all of the filter caps do not need to be changed.

    I also question some of the resistors. I would chopstick all of these. R24, R25 on the power tube sockets. R26, R27. Even R18, R19, R20. As long as your banging around in there R21, R22, R23.

    Address that C10.
     
  19. Q tip

    Q tip TDPRI Member

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    I will do C10 as soon as I get the part. Just a note though is that the static was there long before the tubes red plated. I have chop sticked and cold sprayed everything numerous times and even checked the values of R21, R22,R23, R24, R24 (while installed but still read accurately) with no results. I touched up the solder points on R26, R27, and R23.
    Still wondering if it's not a bad solder joint but I have been fairly aggressive with the chopstick to no avail.
    Thank you very much for the instructions also. That solidify's my method in my head.
    There are not a lot of electronic shops where I live so I will have to likely get something sent via mail.
     
  20. Q tip

    Q tip TDPRI Member

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