5E3 Build, or so it begins.

Discussion in 'The Squawk Box' started by chupe442, Feb 20, 2018.

  1. chupe442

    chupe442 Confused as ever..... Premium Member

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    All parts are ordered.. I should have known I would order them all in a couple of days time as apposed to spreading it out.

    Small parts and chassis - MojoTone ( has eyelet board as apposed to turret. Not an issue.)
    Tubes and Cabinet - Tube Depot (will lacquer the cab upon arrival plus its in stock and much cheaper)
    Speaker - WGS G12Q (WGS has always been excellent to me and there is NO sure winner for a speaker in the $100.00 Range)
    T-formers - ClassicTone. Went with the stock 40-18022 and matched 22. Its what it was designed for. There are plenty of MODs if I don't like it.

    Now, the wait for parts....
     
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  2. Pappy58

    Pappy58 Senior Member

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    Be happy about the eyelet board. I used a turret board and it was a PIA due to space constraints. ..at least for my big mits. :rofl:
     
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  3. Leña_Costoso

    Leña_Costoso Senior Member

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    Eyelets are Mo Betta to repair imho
     
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  4. Cjsinla

    Cjsinla Senior Member

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    I was looking at the specs for the Mojotone 5e3 tranny and they are saying it is 384 0 384. That’s 768v as opposed to 660v for the Classic Tone tranny. Is that possible?
     
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  5. chupe442

    chupe442 Confused as ever..... Premium Member

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    Sure its possible. They are model "numbered " as 756, but not sure if that means output voltage either. Another reason why I just went with the ClassicTone Tranny's in the stock /designed output voltage. Its what was meant to be and no headaches attempting to get the information...
     
  6. Cjsinla

    Cjsinla Senior Member

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    The diagram that comes with the tranny shows the red wires running 384v each. Green is 3.15v and yellow is 5v as you would expect.

    CB47B241-9BD9-4CB6-BBC0-9C83784E8B90.png
     
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  7. chupe442

    chupe442 Confused as ever..... Premium Member

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    What does MOJO do different in values on the board then? Anything? I didnt see any stand-out changes from other drawings that I may need to "counter". Probably good that MOJO is seemingly taking their time in shipping so I can dwell on this a bit more. LOL..
     
  8. Pappy58

    Pappy58 Senior Member

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    Yep they are rated at 384-0-384, right at +10%. As soon as my variac shows up I'm going to power mine up and will reply with some voltage readings when she's up and running as I used the Mojo PT with and Merc OT. Stay Tuned!
     
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  9. Pappy58

    Pappy58 Senior Member

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    I havn't found anything on the board not matching the original spec with the exception of the 100ohm termination resistors on the heater circuit, as they use more of a BlackFace heater arrangement. I found this during my board assy and discussed in my build thread.
    I did go with Mallory coupling caps as opposed to the orange drop, just because the OD's are a bit cumbersome and I had them.

    :cheers:
     
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  10. Cjsinla

    Cjsinla Senior Member

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    I thought that you said you went with the Classic Tone PT, they are 330 0 330, at least mine is. I just got a new Fluke multimeter, my other inexpensive meters gave me readings that were all over the place. I’ll open my 5e3 up tonight and check the voltages against one of those old Fender wiring diagrams if I can find one.
     
  11. D'tar

    D'tar Senior Member

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    The component values look stock 5E3. I don't see any reason to install the foe ground switch and death cap. I also would not follow their power cord wiring scheme.

    the classic tone 40-18021 is 355-0-355, 710v @100ma
     
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  12. chupe442

    chupe442 Confused as ever..... Premium Member

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    I went with the 40-18021.

    In the mean time I have received or received tracking on everything BUT the small parts and chassis from MojoTone. Cabinet and tubes (Tube depot) and speaker (WGS), tomorrow. Tranny's yesterday. Mojo was (at least on web sight) 3-5 days processing. Today they corresponded that they are approximately 2 weeks out on orders and the good news is that mine should be processed early next week.......



    [​IMG]

    I ain't got time for this waiting shit.
     
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  13. Pappy58

    Pappy58 Senior Member

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    Wow...thats really not like them at all, at least from my previous experiences. Must keep an eye on them now! Hope they show up soon.
     
  14. Pappy58

    Pappy58 Senior Member

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    Just a follow up on the voltage specs, here is something I grabbed on Rob.Robinette.com Based on it does seem that the 660v trannies are intended to compensate for higher wall voltage....and does add some credence to the question "why is mojo's spec higher?", if the issue is it already too high? :dunno:

    I think I'm going to send them the question and see if I can get an answer. It's doubly puzzling that the PT they offer for 40w BF amps is 8 volts lower than spec! :run: I have one of the in a Super Reverb I restored and it dials right in.

    But as pointed out on Rob's site, it's how you do the math! Lot's of probing to be done once mine fires up for sure. :cheers2:

    Screen Shot 2018-02-27 at 9.55.34 PM.png
     
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  15. chupe442

    chupe442 Confused as ever..... Premium Member

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    They are in the process of moving the wood shop but nothing about the warehouse. It would have made a difference had I known but to cancel and reorder elsewhere would put me in the same wait now. Not the end of the world, just wanting to be working on it.. This weekend I will be able to start shellacking the cabinet. All is well.

    Yes it would be interesting to see why the lower voltage on the output is the fix yet MJ is higher than the original. Confusing stuff out there..
     
  16. Leña_Costoso

    Leña_Costoso Senior Member

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    1. Compensate for higher wall voltage is a myth, based on the incidental voltage available at Fender's facility when the readings were taken. But... folks look at the Fender drawing, say "oh yeah, I need lower voltage because that's what they had back then, and I want the amp to sound old". Whatever.

    2. A 330-0-330 transformer should rectify out, with a 5Y3 at about 395 volts or so, or perhaps a little less because of the way the 5E3 uses cathode bias (and runs the tubes hotter on account of that).

    3. A 384-0-384 should get about 460v - if that transformer is in fact 384 under load. The Mojo kit uses 475v filters, so ... I dunno.

    4. Could be... that things are not as different than they might initially seem, because we have no idea if the voltage levels are taken mathematically through winding ratio calculation, or, by testing (at what wall voltage!) with, or without load. Too many variables to say for sure.

    5. You'll probably find that with a 5E3 the few extra volts might be welcome, because those circuits are awful quick to break up anyway.

    6. The overall tone will not really vary that much, even with what I said in #5 above. I've played with all sorts of voltage dropping scenarios using reverse Zener diodes. A 40 volt drop doesn't make all that much difference, to the point that I just considered it folly. There are those golden ears that can tell the tone of old growth wood, or if the pick was made from re-purposed Agfa film stock celluloid, or the age of the whale fossil nut by the sustain. I ain't that guy.

    7. More variation will be placed on the speaker choice, the cabinet, the tubes, perhaps the coupling cap type, and finally the voltage difference. The folks who can accurately ascertain the date code of the capacitors and CTS pots of an early 1960's Telecaster, just by playing it, might have their own opinion on that.

    Very interested to see what the 384-0-384 does in a real circuit. Wondering if its a misprint. Hammond transformers are 330-0-330, at 140ma (give or take). They usually rate the current conservatively, and the voltage under load in the expected circuit. Fender's "replacement" is 330-0-330 at 120ma. Nobody says anything about "compensating" with those.

    If you really gotta... you can lower the B+ with a reverse Zener diode, very easily, not too bad on price, under $15 last time I checked.

    And finally, just to let folks know, I've been prodded here locally to produce an amp assembly book, with lots of pictures. I'm thinking about building a 5E3 just for the book project. This is one of those "you know you ought to write a book" thing from some locals that have done the same in their respective avocations. More to come on that....
     
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  17. chupe442

    chupe442 Confused as ever..... Premium Member

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    @Leña_Costoso. It can be overwhelming with the voltage differences and who says what is best and why. Seems most of the issues come about under full load (diming) the amp, which is what I more than likely will never be doing (or most of us home players for that matter). :cheers:

    As for you writing a book, I say do it. You seem to have an ability to write in an way to keep interest and educate at the same time. Personally, not a big reader. My mind wonders if the read can not keep my interest. :)
     
  18. Cjsinla

    Cjsinla Senior Member

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    I checked out my 5e3 voltages last night. The tranny measures 335v at the rectifier. All the levels that I saw on the board were about 10% higher than what Mojotone says they should be. The voltage at the filter caps was 30 to 40 volts higher. I suppose that’s within limits as the Fender drawings say values can be plus or minus 20%. This is the first 5e3 I’ve ever played so I have nothing to compare it to, but I like the way it sounds so it’s fine with me. Much more clean overhead than my 5f1 and grinds when I crank it. So, loud enough to bother the neighbors.
     
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  19. Leña_Costoso

    Leña_Costoso Senior Member

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    Yah but with my book youd get extra value.... Because I'm boring _and_ grumpy
     
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  20. Pappy58

    Pappy58 Senior Member

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    Me neither, nor is he, whoever that may be! :doh:

    Can't be a misprint it's all over all their docs. I'm planning to power mine up this weekend so we will find out. But as stated in my build thread we have used these before without issue, just never paid real close attention to exact voltages.

    :laugh2::lol:
     
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