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Thread: Blues jr. Given me da blues

  1. #1
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    Blues jr. Given me da blues

    I just took my blues jr. Out of storage. After plugging it in it popped a power tube. It might have been handled rough in transit. I checked out electronics, everything looked pristine. I installed 2 gold lion power tubes. Let them heat up well and played. Clean sounds great but amp rattles/rumbles at breakup. Especially on g string. This amp never was used much in past. Not even broken in. Any advice on where to start troubleshooting would be appreciated. Only rumbles after 3 on master dial and 2 on volume. Fat switch makes it worse. I have ordered pre amp tubes. Most likely the problem. Thanks for listening.

  2. #2
    Forum Member Don's Avatar
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    Re: Blues jr. Given me da blues

    The first thing to look at is the tubes and you're already doing that. If it doesn't help, clean the sockets- input, output, tube sockets... I don't spray them directly. I spray a cord end or tube's pins and put them in and out a few times.

  3. #3
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    Re: Blues jr. Given me da blues

    Copied from an ancient thread:
    Quote Originally Posted by Cogs View Post
    I don't know about this particular model, but my old Blues Jr (from the same series) had a similar problem, & only at certain times. It seems the tube sockets had broken loose from the PCB. I'm pretty sure I discovered the breaks while trying to re-tension the connections inside the tube sockets. You'd be surprised how much difference this will make in an amp! They still made enough contact to keep the amp running, but at certain peaks in volume it would rattle the sockets & produce that crackling, shorting-out sound. A little solder & flux, & heating of the joints to re-flow the solder was all it took.
    I'll tell you a little secret but I cannot advise this action, lol:
    To pinpoint the problem, I removed the chassis from the cabinet but kept everything connected. I turned off all the lights in the room, plugged in a guitar, powered it up & played for awhile to see if I could produce the symptoms. In the dark I could see tiny blue arcs in & around the tube sockets that coincided w/the sound. That's how I found it.

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    Re: Blues jr. Given me da blues

    Btw I hated that amp, lol
    When I eventually sold it, it went in a heartbeat. Very popular amps, lots of mods out there

  5. #5
    Forum Member Sérgio's Avatar
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    Re: Blues jr. Given me da blues

    I have just got rid of all my other amps after buying a new Blues Jr Tweed, the one with the Jensen C12N speaker, I liked it so much.

    But the amp is brand new, I have not yet experimented any kind of trouble with it, especially wear related.

    I’d say give it a chance after you figure out what’s wrong and fix it.

    Which model/year is yours? Does it have the green or cream colored pc board?

  6. #6
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    Re: Blues jr. Given me da blues

    Quote Originally Posted by Sérgio View Post
    I have just got rid of all my other amps after buying a new Blues Jr Tweed, the one with the Jensen C12N speaker, I liked it so much.

    But the amp is brand new, I have not yet experimented any kind of trouble with it, especially wear related.

    I’d say give it a chance after you figure out what’s wrong and fix it.

    Which model/year is yours? Does it have the green or cream colored pc board?
    I have the 2016 lacquered tweed green ic board. This amp was in storage for 2 years. It doesn't even have an hours playing time on it. It has the jensen c12 like yours. Its still new. So I'm gonna fix it and mod it. It sounds great with my 22 year old mex. Strat

  7. #7
    Forum Member Offshore Angler's Avatar
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    Re: Blues jr. Given me da blues

    My experience is that when you pull an amp out of storage and it acts up it's usually a corrosion problem. This gets even worse on amps with PCBs since questionable manufacturers don't do a good wash of the board after it's wave soldered. Any remaining flux will eventually end up causing problems. Things like tube sockets full of nooks and crannies are especially vulnerable.

    If any of the solder is turning white the board needs to be cleaned. All caveats about safety and cap draining apply. Don't work on it unless you know how to do it safely.
    "No harmonic knowledge, no sense of time, a ghastly tone, unskilled vibrato, and so on. Chuck is one of the worst guitar players I know" -Gravity Jim

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