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Thread: 1954 Gibson GA-40 Les Paul Coil wax

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    1954 Gibson GA-40 Les Paul Coil wax

    Hi all, I'm slowly restoring a 1954 Gibson GA-40 and noticed some wax on the bottom of 10 henry .12 amp coil. There was also some melted wax inside the chassis but I believe that was from all the paper & wax caps. Now I'm wondering about this coil. I haven't seen this before but this is the oldest amp and the 1st with paper & wax caps that I've worked on. I've included pics. Is this normal and Ok for it's age? At my age, I leak a little wax too, lol.
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    Old Timer Leo_Gnardo's Avatar
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    Lots of wax in those old amps, usually nothing to worry about. Sometimes you get a blob that melted out of hot transformer - I've seen that in 60's Vox amps besides other 30-40-50's amps. When you see that you know the transformer got overheated at some point. If it's still working then on with the show, and if not, well there's the evidence why.

    Now, what's the function of the choke you mention. If it's a filter choke, 10 Hy sounds about right, then you'll want to leave it in place, or replace it if damaged. Rare to see one gone bad, but it does happen on occasion.

    Some older amps have a choke wired across the speaker terminals (!) in an effort to "voice" the speaker. You can imagine . . . a choke there tends to look like a short circuit at lower frequencies. Seen these in 50's Premier amps mostly, but one might show up in a Gibson. If that's the case, I remove that choke. If the amp's owner insists for originality's sake to leave it in then it's a choice of leaving the choke in place for looks while detaching one of its leads, or leaving it wired in place. That's up to you and the amp's owner.

    By coincidence today I'm having a go at a tweed "Gibsonette" with a pair of 6V6's driven in parallel not push pull. They did such strange things back in the day...

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    Last edited by Leo_Gnardo; 09-18-2018 at 08:28 PM.

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    It's part of a Pi filter in the power supply fed by the tube rectifier (5V4G). I am replacing the rectifier tube because the glass is loose but internals look fine and there's no evidence of burning or arcing anywhere. I'm doing this for a good friend who wants to play it. Because of its age and the look of the caps, I did not power it up. I am replacing all the caps for the same reason. I can run her up slowly with a variac when I'm done while keeping an eye on it but I think I'll reach a fair amount of voltage before the rectifier fires anyway. Hopefully, if it's a problem, the fuse will blow before the rectifier. Did you notice the Jensen Alnico in it? That's a first too. So you have a single ended 12W amp? What's the speaker?

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    Lifetime Member Enzo's Avatar
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    What would today be a mylar cap, was then a paper cap dipped in wax. SO heat in teh amp would melt the wax off the caps and it dripped wherever.

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    Yeah, and they were so much bigger then. Maybe that's the mojo. Bigger caps bigger sound. LOL. BTW, Enzo, I went with your suggestion using single caps to replace the cap cans. I disconnected the cans but left them in place then I used tag boards screwed thru the rivet holes on the cans with #4 machine screws. I found that I had lots of space to do that once those paper & wax caps were removed.

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    Lifetime Member Enzo's Avatar
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    Great, though I wouldn't be the first guy to think of that.

    Those waxy paper caps were so much larger than caps today. Usually lots extra room.

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