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Silvertone 1484 Twin Twelve barely functional

Discussion in 'Amp Tech Center' started by Huddy, Jul 11, 2018.

  1. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    So I scooped up this amp last night locally for the low low. It's not working to well though. I've fixed a few amps with filter capacitor issues. So I thought I'd give this one a shot.

    It's an alleged one owner Silvertone 1484 Twin Twelve and I stayed up a good bit of the night reading about their issues and common problems.

    The owner who has had the amp since 66 or 67 he said (speakers date 52 week of 65) never really learned how to play guitar and it's been sitting for essentially the last 40 years. He thought it needed new tubes.

    From what I've read your about the design is that it has voltage doubling capacitors because they're wired in series. When those capacitors go bad the plates do not get the proper voltage resulting in poor electron flow making it severely underperform which is what this is doing.

    You can play it fairly turned up (5+/-) and get very little out of the speakers.

    I'm assuming these capacitors need replacing but they do not have any of signs of the leaking that I've seen on the few that I've repaired in the past. I assume that the leaking of magic juice is not always present in a bad capacitor, yes, no, maybe?

    My main question at this point is... Should I be looking at anything else?

    I'm waiting on a 3-prong cord and electrolytic caps before I get into anything too in depth.

    Thanks to all in advance!

    View attachment 528501 View attachment 528502 View attachment 528503
     

  2. BobbyZ

    BobbyZ Doctor of Teleocity

    Jan 12, 2011
    Snellman MN
    Tubes might be just fine, not being used is good for tubes. Those amps came with tubes that'd be expensive as NOS today, so hopefully they're good.
    Electrolytics are the other way, non use isn't good for them, but regardless at 50 years I'd replace them all, no matter what. I don't doubt they look good, but if you use them awhile they won't.
    As I recall those amps used cap cans. C&E might have something that'll "bolt in" or there's probably room to mount individual caps inside too.
     
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  3. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Before putting any more electrons through the circuit, I would recap it. Electrolytic cap weakness or failure does not necessarily make itself known visually.
     
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  4. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    @BobbyZ thanks! I think you just confirmed all of my assumptions.

    Yes the filter cap is a 3 part can with 20-10-5 uf values.

    I got 3 f&t caps to replace the can - 22, 10, & 10.

    They had some replacement cans that could have worked (20/10/10/10) but they were all 4 section and I felt if I was going to go through the trouble of replacing the fitting I might as well just use the three separate caps for 1/3 of the price.
     
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  5. Platefire

    Platefire Friend of Leo's

    Age:
    70
    Nov 3, 2003
    North Louisiana around Many
    Good Score! As one that has worked on a lot of vintage amps, in addition to new filter caps, I would get a can of Deoxit D5 or another high quality contact cleaner. When you have the chassis pulled to install the new caps:
    1-Pull all tubes one at a time. With the tube pulled spray cleaner into the tube socket and on tube pins. Then work the tube up and down several times before the cleaner evaporates. It usually evaporates pretty fast.
    2-Spray cleaner in all the switches and work the switch back and forth before the cleaner evaporates.
    3-Spray cleaner in the back opening in the pots and turn the pot shaft vigorously
    before the cleaner evaporates.

    I've seen this treatment alone bring old amps back to life, so I think it's very important in bringing the old amp back up. Corrosion/oxidation takes it tole especially on amps that has been sitting up. So the better/cleaner the contacts are on this amp, the better it will sound. Platefire
     
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  6. jrblue

    jrblue Tele-Meister

    491
    Nov 14, 2010
    Santa Barbara
    If you do this work yourself, make sure you know how to drain the caps so you don't kill yourself with residual voltage. The "prone to failure" elements described in the posts above all deserve attention. Unfortunately, when you've got it working again it will still be a Silvertone.
     
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  7. jimbo735

    jimbo735 Tele-Holic

    980
    Sep 19, 2011
    Michigan
    They are a great sounding amp I watched a three piece country rock band locally and the tones the guy was pulling out of that amp were incredible,and his pedals didnt seem to slow it down any.
    You did very well Sir.
     

  8. Nickfl

    Nickfl Tele-Afflicted

    May 24, 2016
    Florida
    It might have been unfortunate back when they were being sold as cheap store brand amps in the 60s, but they are considered to be pretty desirable amps these days and rightly so IMO...
     
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  9. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    Definitely minding P's and Q's on the caps. I do not, however, employ the Caesar Diaz method à la screwdriver across the high voltage to chassis. Looked scary.
     

  10. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    Here's some pics for reference... I don't know if the others got uploaded properly.

    1531362657124.jpg 1531362664350.jpg 1531362672590.jpg 1531362720290.jpg 1531362726530.jpg 1531362730850.jpg 1531362738546.jpg
     

  11. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    Are these speakers C12Q but the Q's tail absent? Or is C12O something?
     

  12. XpensiveWino

    XpensiveWino Tele-Meister

    373
    Jan 6, 2013
    Banner Elk, NC
    Yeah! I scored a Vintage Silvertone from my local Habitat for Humanity for $15, and the thing is sexy sounding. I still need to go through mine. IMO ignore the comment about it "still being a Silvertone." These things are cool. Good luck, let us know how it turns out!
     
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  13. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    Damn I thought I swiped mine but $15 is kinda stupid... The thrift stores around me never get any good stuff. Just picture frames and coffee makers. If anything good did happen to pop up it'd be full retail and not functioning.
     
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  14. wanderin kind

    wanderin kind Tele-Meister

    Age:
    63
    219
    Apr 24, 2018
    Olympia WA
    nice amp! that's the good news.

    the bad news?

    that chassis is not very user friendly to work on.

    and that chassis needs a lot of work.

    i would replace the power tube sockets. this is a PITA. but those old sockets and resistors and solder joints get pretty crusty. And the original sockets are marginal with evidence of arc-over, so ceramic is the way to go, with tube retainers.

    the dry lytic caps need replacing,

    you are not fixing an amp like this, you are restoring it, which is a lot more work. some of those people who wired those amps did it mil spec style, which means they tie knots in all the resistor, capacitor and wire leads. so getting parts off the old terminal boards is a chore.

    tighten all the hardware, ie input jacks and pots, if there is corrosion underneath the jacks and pots, you can hit it with fine sand paper and then deoxit. i would probably go for some Switchcraft 12B jacks while your at it, digikey has good prices on those,

    spray the on/off switches also.

    be careful with those small output transformers, the cardboard gets cooked and it is easy to rip a lead through the wrapper.

    if you do the pwr supply and power tube sections, then you are home free. usually the preamp section does not need much work. check the carbon comp resistors, i bet every one is 20% high. if one is open, replace it otherwise leave the drifty parts or risk losing the funk.

    oh, and those coupling caps to the power tubes, change those also.

    and of course, the first thing you do is check all the tubes.

    one good mod is to add a terminal strip and run the heater wires to it. then distribute the heater wires to the preamp tubes with one set of twisted leads, and the power tubes with another set. this cuts down a bit on clutter and provides a more bullet proof heater circuit. the stock amp runs a lot of heater wires off the poor overworked power tube sockets.

    that crazy power supply with the doubler and dual xfmr windings can be hard to wrap your head around, and the bias circuit is probably in need of a rebuild also.

    here is the OPT info for any stalwart DIY types who wanna wind their own 1484 transformers, or repair a bad one, i used grain or .014" lams instead of the .025" barn roof lams. note the funky 4 ohm tap that is mathematically incorrect for keeping the same P-P plate Z when using a 4 ohm load,> sears silvertone 1484 OPT.png
     
    Last edited: Jul 12, 2018

  15. Boil

    Boil Tele-Meister

    317
    Oct 30, 2011
    B.C.
    Hmmm a guy I used to play with had one of those, it sounded pretty good, another guitarist I play with occasionally has a 1482 (I think, single 12" ) it sounds pretty awesome, good score.
     
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  16. BobbyZ

    BobbyZ Doctor of Teleocity

    Jan 12, 2011
    Snellman MN
    Looks really nice !
    Pretty sure those are C12Q, and the guy printing that day was looking at the woman putting labels on. Or drunk. Lol
     

  17. jrblue

    jrblue Tele-Meister

    491
    Nov 14, 2010
    Santa Barbara
    Yeah, I recognize that people will object to my "still a Silvertone" comment. As I say, some people like 'em for their music. I owned one back when it was new, and it got played to death by me and others because it was all we could afford. (That was the point of Silvertones -- the cheap alternative.) It was loud and harsh, better than cheaper amps and worse than Fenders, etc. Sure, there's a Renaissance of players using marginal old guitars and amps, and who am I to judge except for myself. But I sure remember back in the day that those of us who used that equipment did so for financial, not artistic reasons, and every single living one of us dumped that amp or guitar as soon as we could get our grubby hands on a "real" piece. That's the truth. But heck -- my most-played acoustic is a Gibson-mde ladder-braced Ward's cheapie from 1936, so who knows. For most o us, it's still a matter of what we can get our hands on, and making it work for us.
     

  18. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    I consider these amps to be “low res”......and I like them in that context.
    Re: that speaker code. It does appear to be C12O, which is a designation I have never seen or heard of. ???? Taking a really close look, the stamp seems to be made close to the outside of the rim. Perhaps the tail of the Q did not witness on the curved edge of that rim?
     

  19. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    C'mon man!!! Why you gotta do that to me...

    I'm new at this and what you just described sounds like hazing. Would probably be easier to start fresh.

    You're absolutely right about all the wraps and knots in the wire leads. It's going to be awful.

    Any best practices? Or just heat and wiggle?

    I'm with you but I've got to take some baby steps.
     

  20. Huddy

    Huddy Tele-Meister

    Age:
    35
    458
    Nov 5, 2016
    Newport News, VA
    It's cool. You didn't hurt my feelings. I've got a few nicer pieces but I'm cheap and very much a make-it-work kind of person so this one suites me.

    I also feel like if you can take one man's trash and somehow make yours or another man's treasure with it (musically) or out of it (go to amp or guitar) it all that much more inspiring.

    Like @Wally was saying up above... Everything has it's own context and how and when you use it, that is what makes it sound "good"

    At least that's what I took from it...
     
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