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1963 Reverb unit two prong plug

Discussion in 'Amp Tech Center' started by jlott, Jan 19, 2021.

  1. jlott

    jlott Tele-Meister

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    Hello experts,
    I am wondering how dangerous this two prong plug is. Wondering if there is a safe way to use it. The amp tech I know says everything needs changed immediately. Caps, plug etc.
    Is there a safe way to mess with this thing until I can get it into a tech. He is running weeks behind. Is turning this on in its current state dangerous?
    Thanks,
    Jeff
     
  2. Diverted

    Diverted Tele-Meister

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    You could put it on an isolation transformer or take your chances.
    But the only solution in my opinion is just to replace it.
    The amp has aging caps in it that are probably leaking DC, a death cap line to ground cap that could short, etc. Best bet is to have the cap taken out of circuit and get a three prong cord installed. It's a simple job, a reasonable tech should have it done while you wait.

    Edit: This presumes it doesn't also need new power supply filters, bias cap etc. If they're original or getting old they should go too if you plan to play it.
     
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  3. no doz

    no doz TDPRI Member

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    I'm with Diverted. If you plug the two-prong power cord in upside down and there is an issue with the "death cap" (which is likely given the amps age), it could prove to be very dangerous / potentially fatal. If I were you I'd wait a few days for a tech to replace it with a proper power cord and not risk the zap
     
  4. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

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    Well...it's not like it has an OT that drives speakers...if you firecracker a cap, it might not take any rare components with it.
    And I'm pretty sure they don't have a death cap.
    I have a '63 (tuxedo colors), but I serviced and it when I got it.
    It sounds like you just want to take it for a spin.
    If it's been in use, I'm guessing you could keep using it.
    If it's been sitting a long time, waking it up with a variac or at least a lightbulb limiter might be a good idea.
    A lightbulb limiter is an easy project if you don't have one.
     
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  5. Boreas

    Boreas Friend of Leo's Silver Supporter

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    View attachment 810265 View attachment 810266 Death caps won't usually kill you unless you are fiddling about inside the amp. But as mentioned above, it is unlikely it has one. But you should at least use a lightbulb limiter mentioned above to keep your repair bill down if something is wonky inside. The two-prong plug really isn't a big deal safety wise if you are just testing it, but definitely change it out when you get a chance.

    Build yourself a lightbulb limiter (cheap) and give it a careful try. Also, check the value of the FUSE and make sure it is correct before you power up.

    This is an excellent reprint of the manual of the 63 REISSUE.

    https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjtuv6vhqnuAhUYXc0KHQiABeIQFjAGegQICBAC&url=https://schematicheaven.net/fenderamps/63_reverb_manual.pdf&usg=AOvVaw20ONT8bgSOQk_WQeY4ghx8


    These are the ORIGINAL schematics, but I don't know the year. They don't show a death cap.



    2021-01-19_17h40_22.jpg 2021-01-19_17h41_31.jpg
     
    Last edited: Jan 19, 2021
  6. dogmeat

    dogmeat Friend of Leo's

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    well if its Fender, like a 6G15 there is no death cap or polarity switch. if you can solder, replace the cord your self. put the line power to the fuse. neutral to the other transformer lead and the ground can go to any part of the chassis, preferably one of the transformer terminals.

    actually, you could install a new cord with wire nuts. the schematic shows power coming to an aux receptacle, I would bypass that since no modern plug will fit it anyway. you could just cut the wire there and splice in a cord.

    on the standard 3 pin plug, the thin prong is "line", the wide prong is "neutral" the 3rd pin is ground.

    on modern cord caps (ends) the gold terminal is line, the neutral is silver, and the ground is green

    https://el34world.com/charts/Schematics/files/Fender/Fender_reverb_6g15_schem.pdf


    edit: looks like Boreas beat me to the schematic.... postin at same time
     
    Last edited: Jan 19, 2021
  7. dogmeat

    dogmeat Friend of Leo's

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    the only other Fender Reverb unit I see is a more modern design that has 3 a prong power cord. only other thing I can think to add is if you do install a cord be sure to secure it to the case or chassis with a clamp of some kind
     
  8. Wally

    Wally Telefied Ad Free Member

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    When I serviced the 6G15 I had, I installed a three wire AC cord as well as a partial ground lift circuit to eliminate the possibility of a ground loop.
     
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  9. jlott

    jlott Tele-Meister

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    19AE127B-8B50-467D-9C18-8037D3DC70EF.jpeg 4ED7BC42-AE71-4A73-9C14-89614F2CF5E1.jpeg 1B107473-E08B-48B0-8B15-75CBFAECDA93.jpeg Sorry for not clarifying. It is a 1963 Fender Reverb unit. Seller is a local dealer. Said his tech went through it and it is working perfectly. Pretty clean for almost 58 years old. Thanks for the replies.
     
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  10. Jon Snell

    Jon Snell Tele-Holic

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    In the UK, shops are not allowed to sell used electrical items without a safety electrical test. If there is no earth lead, it will fail and deemed as unsafe. This item is too old to be known as "double insulated" and not require an earth.
    It only takes a few minutes to replace the mains lead with a three core lead.
    The method used has been covered on this and many sites, many times.
    If those Mallory capacitors are not bulging, they are probably as good as new ones.
     
  11. Javier668

    Javier668 Tele-Meister

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    Change the cord, dont need a tech for that.
     
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  12. W.L.Weller

    W.L.Weller Tele-Holic

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    I'm not typing this to advocate against swapping the cord for a grounded one. This is a pure hypothetical, since I don't have a reverb unit, grounded or not.

    Could you use the "courtesy" outlet on the back of e.g. a grounded Fender Twin to plug the 2-prong reverb unit into and be safe that way?

    In thinking about it for a moment, it seems like the answer is no, since there's no direct connection between the chassis of the reverb unit and ground.
     
  13. Wally

    Wally Telefied Ad Free Member

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    The date codes on the two trannies date to 1964....606406 and 606408...6th and 8th week of 1964. one cap under the dog house has a Fender ink stamp from the 24th week of 1964. One cap inside has a manufacturer’s date code from the 16th week of
    1964...235 6416. If there is a tube chart, there should be a date stamp reading ‘N_’...you have a beautiful unit built in the summer of 1964. Congrats...
     
  14. Boreas

    Boreas Friend of Leo's Silver Supporter

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    Thatsa beauty! Appears pristine inside. You were originally asking if it was safe to fire it up. If it has been tested and played lately it is PROBABLY OK to try it. I would still recommend using the lightbulb limiter. But the caps look OK from here.

    Most competent amp techs would recommend changing out the old caps and power cord, and so would I. The existing caps could last another 20 years or 20 minutes. The death of a cap can be innocuous, or it can be damaging. It isn't difficult to replace them yourself if you have good soldering skills and know your way around an amp. But if you are Jonesing to try it out, and it has been tested and played recently, make yourself a limiter and play it until you can get it serviced.

    Enjoy!!
     
  15. Boreas

    Boreas Friend of Leo's Silver Supporter

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    Yeah, it would be no different than plugging it into a 2-hole outlet in the wall. Not a good idea. Don't do it while taking a bath. Some people don't change them to retain their unmolested value, but they don't likely play them. Fine if you are going to put it in a display case, but for regular use, change the cord and caps.
     
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  16. jlott

    jlott Tele-Meister

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    The shop I'm buying it from is having their tech change to a grounded three prong cord. I will it get it to my usual amp tech when he's not so swamped. See what he thinks should be done, if anything, to keep it sounding great for a long time. Thanks for all the replies.
     
  17. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Personally, that's the worst thing you could do, in my opinion. Adding a three-prong cord gives the illusion of security - "oh the amp is safe, it's got a grounded cord!" But the you have all the ancient caps in there just looking for a reason to explode.

    I've people ask me to do that job and I refuse it. "Oh hey, I can't afford a full cap job right now, can you just do the power cord change for me?" Nope, because I'm not going to be the last guy that touches it before something explodes.

    I've never seen a fender with the orange Mallory caps that didn't have at least one leaking.

    So, it's fine to have them do the power cord change, but I wouldn't use it until it had a full proper service.
     
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  18. jlott

    jlott Tele-Meister

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    I'll ask the shop about doing the servicing. What usually needs to be done and what is a good price. I'm not a collector and I just want this to last and be good for the future. I'll give it to my son one day.
    Thanks
     
  19. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Hard to say what a good price is as I don't know the rates of the Detroit area guys.

    I tell everyone the same thing - you need the general service first. That includes the power cord, caps, clean contacts and all that good stuff. Make sure the amp itself functions. Then, you can actually test things and see if resistors are noisy, or coupling caps are leaky, or if a tube is noisy or not working properly.

    These aren't an expensive amp to work on by any means. 3 big caps and 5 little caps, no big deal.
     
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  20. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

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    There are electrolytic filter caps under the cover that need to be changed.
    There are also electrolytic "bypass" caps that need to be changed.
    The "tone" caps need to be checked for leakage...not physical leakage, but DC current leakage.
    For my money that's the bare minimum that should keep anything from going BANG...really.
    After that, you can check for drifted values of resistors.
    Replacing those will get the unit running tip top and reduce the possibility of breakdowns.
    I don't want to encourage half-assed behavior, but I have heard amps that I thought sounded just fine with some pretty out-of-spec resistors.
    OTOH, it's no biggy to change them.
    I would GUESS 150-200 for a full service, but my guy is really inexpensive and he may have spoiled me.
     
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