Weird Tweed Power Trans in Brown Fender Super

Discussion in 'Amp Tech Center' started by ocduff, May 13, 2019.

  1. ocduff

    ocduff Tele-Meister

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    Scored a pristine '61 6G4 (A handwritten On tube chart and circuit is 6G4-A) brown Super. Original down to the Amperex Bugle Boy 7025's and Astron Mini-Mites. Original Tung Sol Power tubes.

    As you can see it has a non-original power transformer. A 6516 Triad, if I'm correct - a tweed Twin and Pro transformer. The original must've bitten the dust early on and this was available. It has no center tap so there are two resistors coming off filament pins on the first power tube to ground on chassis. Really cool.

    I immediately broke original power cord when unplugging it (it got stuck in outlet!?!), so a 3 prong got installed and ground switch and death cap bypassed. So much for going to the museum.

    Anyway - just pumped about this score. Amp sounds amazing - trem is a bit weak. One Tung sol was shot, and replacing it brought amp to life. Previous owner bought it off original owner who never played it much.

    Will this incorrect power transformer work correctly? I see no sign of original failing having taken anything out, or how the previous one was wired in. Was Fender ever known to use up old transformer parts from the parts bin in newer amps? This amp has a mix and match of Astrons and Blue molded caps. Weird.

    Anyone know specs on this PT? Voltages are 460v with tubes at about 28ma. I thought the 6516 was a stand up type transformer. Any info here appreciated on this unusual power transformer. Amp sounds good! Readings are all bang on.
     

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  2. ocduff

    ocduff Tele-Meister

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    A few more shots for those interested.

    Any facts on incorrect PT is appreciated. Can't find much info out there.
     

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  3. Wally

    Wally Telefied Ad Free Member

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    Congrats. Tech assessment and work is necessary, imho. You don’t show us the positive end of the filter caps....that is the end that will show visible signs of weakness. We see only one small shot of the board. There is one electrolytic bypass cap replaced there. I would be replacing those filter caps. The death cap is present, and the power cord needs to be updated to a grounded cord. It is a clean looking amp.....too bad about the PT. C’est la vie, and the price was adjusted for that major non-originality one would hope. As long as the voltages are good and it will support the current draw of all of those 12A-7’s, play on...after the proper service is done.
     
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  4. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    Good googely moogely! That thing is stupid clean!

    You wouldn't be looking for a kidney by any chance? I have an extra for trade....


    Sorry, I can't add any real value to this conversation. I know diddly about specs and such. But I just had to say how beautiful that amp is!
     
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  5. ocduff

    ocduff Tele-Meister

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    Thanks guys. Price was low. :) It has had basic service to get vibrato working.

    I just removed death cap and installed 3 prong. Debating on the filter caps as they appear leak free. I know default is just to replace (kind of like how everyone paints chimney bricks and wood trim white these days defacto) but I'm sleeping on this - parts are already on order. Caps are still sealed and apparently doing their job - for now. :)

    The PT is weird. I'm not suggesting by any means it's original but egads, it's a head scratcher. Usually you see an undesirable transformer (not a valuable one) hacked into place a sloppily wired in with boogered nuts and marks on chassis from getting it in and out (as I did when carefully, or so I thought, removing the old power cord strain relief ) I can't even see a mark to indicate those transformer bolts have been turned.

    Really digging the amp. Strong, bright, and (I use this disgusting word without reservation here) CREAMY.

    It really is clean. That is why I am very poor at the moment. I saw it and literally sold crap until I had the cash.
     
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  6. schmee

    schmee Poster Extraordinaire

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    Wow, that thing is clean inside. Nice score. And those 10K5 Oxfords! I dont know about the tranny, but being an early brown amp, one wonders if that tranny might be original. It doesn't look messed with much inside.
    Definitely replace those filter caps though. Put the new ones inside those paper covers if you want.
     
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  7. Nickfl

    Nickfl Tele-Afflicted

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    More like how everyone would put new tires on a 60 year old car, defacto.
     
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  8. Wally

    Wally Telefied Ad Free Member

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    Ocduff, I’ll give a look at my transformer charts when I get to them. There can be some odd things that went on back then. Iirc, the PT ‘should be’ a 125P5B. What do the solder joints look like?
    Filter caps....ime, caps that old are not doing their job to the best extent no matter what they look like. The sonics of the amp will improve, ime, with fresh caps.
     
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  9. ocduff

    ocduff Tele-Meister

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    Part of reason I'm even questioning PT (despite it being incorrect for this amp) is because I'm debating eventually removing it and selling it - as it is a Triad Tweed Twin transformer as well as I know, and that's gotta be worth some coin. It looks new (where's the rust and scratches and spliced leads you usually see on an old "re-purposed" transformer?). Still need more info there.

    I haven't owned a vintage amp of guitar in 15 years - I usually build guitars and amps if I want them and tweak away and remove and replace and scratch and dent stuff with impunity. Here I'm just being thoughtful. If I decide tomorrow I don't want the amp, besides doing the right thing froma service standpoint, have I done the right thing by replacing those caps? It's like you can't win because we all don't share the same ideologies regarding vintage stuff - even many would rather have original cord and death cap in place than have a three prong cord. Right or wrong, it's their money to spend.

    Anyway - for now I'm just trying to find out what this transformer is and why it's in there. Everything is speculation of course, but I'm having fun speculating. Ie - transformer failed in 1967. A tech took a power transformer out of a wrecked tweed Twin? Or called Fender and this is what they sent as correct transformer was unavailable?
    Or - Fender got rid of surplus transformers by slipping them into production runs when they saw fit. Who would ever know?

    Here's the wiring of the resistors off the filaments - same type of carbon resistor and solder (although that seems like a dumb assertion, it looks like every other solder blob on there and those of use who use soldering irons, that's almost like a fingerprint) to chassis as the era. So if replacement was done it was done with same exact brand and era type of resistor used in amp. Is it possible a tech in Massachusetts in 1967 had a Tweed twin transformer on the shelf in a box and exact type of Allen Bradley resistor on hand to make the repair? Sure it is. But seems at least as much of a reach as saying it's original, even if incorrect.

    I'm not selling the amp or asking anyone to verify anything or pass off the transformer as original to anyone. I'm just trying to square this riddle in my mind, because it's just not something I've seen done before, and I'm having fun. I don't want to rip it out and then have someone chime in and say "hey I own a '61 Pro with same PT and wiring" as remote as that possibility is. That's all. Being thoughtful before proceeding is all.
     

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    Last edited: May 14, 2019
  10. Viejo

    Viejo Tele-Afflicted

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    Early Brown Supers came with Triad transformers not Schumacher. Also I would bet that amp is a 60
     
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  11. Wally

    Wally Telefied Ad Free Member

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    The solder joints to examine would be the connections at the ends of the primaries and the secondary windings. Sometimes it is hard to see any clues of non-original soldering...sometimes it is easily seen.
     
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  12. knavel

    knavel Tele-Meister

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    This.

    I have a May 1960 Super and it has the Triad transformer. I would put up pics right now but I'm traveling and won't have access to my photos till the end of the week.
     
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  13. charlie chitlin

    charlie chitlin Doctor of Teleocity

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    That one bypass cap and 2 resistors replaced, but death cap still in place?
    Fishy.
     
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  14. AJBaker

    AJBaker Friend of Leo's

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    What an amazing find! Beautiful amp!

    Definitely change the filter caps though. Like 60s car tyres, as someone just pointed out, there's no sense using them in the hope they might not fail. Change the caps and preserve the amp from bad electric jolts down the line.
     
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  15. ocduff

    ocduff Tele-Meister

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    I think it's a late '61 - next production run probably had the wheat grill cloth.

    I'll snap pics at rectifier when I have it open next. The black power windings I've already un soldered to install the 3 prong cord.

    I took these pics before that to document it.

    This amp was serviced before I got it to get the tremolo working and have bypass caps replaced. Not saying someone didn't replace the transformer then with a tweed transformer. That just seems kind of silly, but it's possible. There's lots of things that tech didn't fix then - like old filter caps, a bad power tube, and removal of death cap. There's guys like Skip Simmons who are of the "if it ain't broke" mentality.

    Keep in mind guys I'm not saying Leo Fender himself installed this transformer when a production run was short a transformer.

    My first question is if this transformer will work properly and specs out to the amp correctly. Second, it's worth considering that it's original to amp before pulling it. Like I said if it's a $$$$ transformer and not original to amp or even right for it, I'll pull it and sell it and install a proper transformer.
     

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  16. ocduff

    ocduff Tele-Meister

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    And thanks all for the replies. Filter caps are on order. Will replace. Those Astrons just look so nicccce. Gonna stare at them a while before I pull them.

    And serial 4001 puts it in 1961 but I can't make out
    Production stamp on tube chart.
     

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  17. Wally

    Wally Telefied Ad Free Member

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    That date stamp in the upper right hand corner of the tube chart reads “K_”...probably a G...could be a C. A KC is March, 1961....KG is August, 1961. The other component dates might define things. The serial number chart yo7 show indicates a date later in 1961....so I’ll go with KG.
     
  18. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    It doesn't matter how they look or even test. They have a service life of 15-20 years; after that they can cook off with absolutely NO warning. AND take out your power transformer. It makes no sense to leave old filter caps in place - as previously noted, it's like changing tires on a car, except you can usually see if tires are going bad.

    Only leave them if the entire amp is in museum quality condition and will never be played - only displayed.
     
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  19. ocduff

    ocduff Tele-Meister

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    Good eye - don't know how you made that out but it started to become clear to me - I see KG now.

    So that dating sheet I had posted says that basically Fender had serial numbers of 2000-4500 for 1961 for the Super. Now is it really possible they made that many supers or do these numbers overlap with other models (i.e. a Pro could have a 3601 serial).

    Seems like a lot of amps - these things weren't cheap back then when you see the price lists.

    Am replacing filter caps. Still interested in the PT - any idea it's specs or which amps used it and perhaps value as a functioning PT? If there's not even a remote possiblility Fender put it in there in a pinch, I'd as soon sell it if it's not doing the amp any favors in the originality department. I know I'm the owner and I'm thus biased, but there's a lot there that makes it appear it's at least worth considering that possibility before pulling it out.
     
  20. peteb

    peteb Friend of Leo's

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    I think the solder joint on the PT center tap is original and the solder joints on the the added filament ct resistors are too.

    That makes the PT original to the amp and the PT the most valuable PT for that amp.


    The 6G4 and 6G4-A schematic both show the (triad) 8087 PT, same as the tweed bassman.



    The tweed twin schematic shows 7993.


    Look at the input jacks. The 68k input resistors are mounted on the jacks on the 6G4-A, on the board on the 6G4.


    Your plate voltage is right on for a 6G4 and slightly high for a 6G4-A going by the schematics.


    Awesome amp. I like that it retains the tube rectifier.
     
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