Well, that was disappointing

Discussion in 'Amp Central Station' started by Milspec, Feb 13, 2020.

  1. Milspec

    Milspec Friend of Leo's Silver Supporter

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    I will be sitting in with a few friends of mine this weekend and we were holding a little practice at my house. They are mostly a folk trio with a little jazz thrown in...not really my generes, but it is fun to join in at times.

    I was using my Godin Kingpin II through my '79 Twin (my favorite combination for bright jazzy stuff) and we were really clicking as a group and then blink...fuse blew. I had been playing for about an hour and not pushing it hard at all, but what was really odd is how there was no forewarning at all. No odd smells, no odd sounds, no crackling, nothing...just blink and gone.

    Sadly, I didn't have another fuse to replace it with (4 amp slo-blo) so I had to switch amps. I'll pick up some new fuses this week, but I have never had a fuse blow on any of amps before without some indication that a problem was developing. I keep my gear well serviced and this Twin was just serviced 6 months ago...although tubes are about 3 years old now.

    Just driving me a little crazy right now, without that fuse, I can't investigate the cause and I am already dreading the possibility of having to drag it 40 miles away to the tech.

    Sort of ruined a really good day.
     
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  2. rolandson

    rolandson Tele-Holic Silver Supporter

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    Perhaps the fuse blowing is the indication of a problem developing...
     
  3. brookdalebill

    brookdalebill Tele Axpert Ad Free Member

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    Often power tube failure will cause a fuse to blow.
    Not always, but often.
     
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  4. Milspec

    Milspec Friend of Leo's Silver Supporter

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    Well, there is that. Will find out soon enough
     
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  5. rolandson

    rolandson Tele-Holic Silver Supporter

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    Here's to that it be nothing more than a weakened fuse, having given its all, and going out in a blaze of glory...as fuses are want to do when their time is at hand!
     
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  6. Milspec

    Milspec Friend of Leo's Silver Supporter

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    That would be nice, would rather not spend $200 on tubes right now. It sure sounded fantastic right up til it died, so there is some hope. Maybe get lucky it being just a preamp tube...have a few of those in my inventory.
     
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  7. The Ballzz

    The Ballzz Tele-Afflicted

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    Pretty rare for a preamp tube to take out a fuse. On the other hand, an "errant" power tube bowing a fuse is exactly what all hope & expect that the fuse was there for in the first place!

    If a new fuse blows, don't put another in until you've swapped out the 4 power tubes. You do have a "spare" quartet of power tubes, don't ya? I hope it's just a bad tube!

    Just My $.02,
    Gene
     
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  8. Milspec

    Milspec Friend of Leo's Silver Supporter

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    I do have a quad set of JJ's on the shelf, but I really don't know if I would go that route. I've used them in the past and found them okay, but not my favorite tube.

    I am just surprised that a tube would fail without any indication leading up to it. One second it was beautiful and then gone. Now the bedroom light did flicker at the same time...could have been a spike of some kind, but none of my other appliances seemed to be affected. I don't mean to harp on this, all tubes go bad at some point, but I am used to there being some warning (scratchy noise, microphonics, etc.) and not just a blink and gone.
     
  9. dogmeat

    dogmeat Tele-Afflicted

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    "sounded fantastic right up til it died"... the classic tube death indicator

    be sure to test the rectifier tube as well... seen that before. power tube claps out and takes the recto tube too
     
    Last edited: Feb 14, 2020
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  10. El Marin

    El Marin Tele-Afflicted

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    Get another fuse.... actually, a bunch of them

    It can also be a fuse failure. I had one of those... or maybe is a tension problem, not yours... a fuse went out years ago in a gig, I replaced it and 10 years later the amp is still working fine

    Always keep a spare fuse, or a couple, attached to the chassis with tape
     
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  11. BobbyZ

    BobbyZ Doctor of Teleocity

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    Pretty sure it ain't a rectifier tube issue in a Twin Reverb. (insert face palm here)

    :)
     
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  12. BobbyZ

    BobbyZ Doctor of Teleocity

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    Did the service include replacing all the electrolytics? Some techs won't do um all if they look good. Those guys should be avoided.

    Here's what you can try. Pull the power tubes and stuff in a new fuse turn it on. If the fuse holds try it with the power tubes. If it blows then you know it's a power tube. If it doesn't maybe you got really lucky and the fuse just popped.

    Once I got lucky with a fuse. I just serviced a mid 70s Twin Reverb. Had to replace the fuse holder and just pulled one out of some old thing I had laying around, it had the right fuse already. Everything worked on the bench so I put back in the cab and start playing it. Damned fuse blows! I dig out my new ones, put a light bulb limiter inline and all indications were good. Ended up keeping the amp about a month and played it pretty much every day, the new fuse held. It's been over a year and the customer hasn't had an issue.
    Other than that I think every one blew for a reason.
     
  13. Milspec

    Milspec Friend of Leo's Silver Supporter

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    I am getting optimistic right now as the IR ceramic heater in that room doesn't heat up since the amp failure. I think there might have been a power spike and although I use a Furman Power Strip, I am starting to think it was the power supply more than the amp. I just don't have time to find out until tonight. It also means I have to leave that room door open since it is only in the teens outside today and that room would get pretty cold closed up. It will not help the humidity situation, but I can't win both fights.
     
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  14. muchxs

    muchxs Doctor of Teleocity

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    Good thing about a Twin Reverb is it has four 6L6s. It will work just fine on two if you pull the bad one and one more.

    This week's cold weather adventure is Girlfriend moved her parents into a nice circa 1968 ranch house across town. Bad news is although it was extraordinarily well built when it was new, it is no longer new. Its 1968 vintage Utica boiler w/ Wayne burner has chugged on admirably for 52 years. It's like a roof that doesn't leak until it rains, though. It waited for the cold weather to get soggy and hard to light.

    I can't begin to tell you how much I'd prefer to work on an old Twin Reverb instead of a 52 year old Wayne oil burner that's soggy and hard to light.
     
  15. schmee

    schmee Poster Extraordinaire Silver Supporter

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    You are using slo blo fuses right?
     
  16. BobbyZ

    BobbyZ Doctor of Teleocity

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    @muchxs At least a boiler from 1968 won't have a bad printed circuit board in it you can't get a replacement for. With now obsolete parts on it you'd have a hell of time replacing if you could get them.
    But on the flip side since is old enough to be repaired you can't just tell um they need to call the furnace dude and get it replaced.
    So really you're screwed.
    Go-Joe might get most of the soot off. :)
     
  17. muchxs

    muchxs Doctor of Teleocity

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    Most of the problem is the system is loaded with accumulated sludge. We hit Home Depot before it closed, bought a quart of Sludge Buster. A quart treats 1000 gallons. There are 125 gallons in the tank. We poured half of it in.

    Another part of the problem is the in- laws are using two electric heaters. One of the heaters is pointed straight at the thermostat. They can't figure out why it's cold in the bedrooms and the furnace isn't kicking on.

    I figure the problem will solve itself when they get the electric bill.
     
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  18. 73camarors

    73camarors TDPRI Member

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    I have an old supro with 6973 power tubes and I just happened to be looking at the back of the amp when one of the tubes flashed blue and popped the fuse. I replaced the tubes and fuse and it's all good.

    Sent from my SM-N960U using Tapatalk
     
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  19. tubelectron

    tubelectron Tele-Holic

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    @Milspec ,

    A useful tip - if your tech did not thought about it :

    On 60s/70s Fenders, the power tube sockets may become loose with time - I mean : the pin holders need th be retightened to hold firmly the pins of the 6L6.

    I very often see this issue, even on more recent amps, no matter if they have spring retainers or not.

    A sudden poor contact there may lead to a sudden tube "failure"-like that could blow the fuse. I wrote "failure" because the tube that suffered the false/intermittent contact in its socket may not be damaged at all.

    If I were you, I would also check that point... ;)

    -tbln
     
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  20. getbent

    getbent Telefied Silver Supporter

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    no one has discussed the short term benefits of tinfoil yet? ha ha ahahhaha
     
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