New 5F2A build!

Discussion in 'Shock Brother's DIY Amps' started by SebC, Dec 12, 2019.

  1. SebC

    SebC Tele-Meister

    Age:
    41
    Posts:
    253
    Joined:
    Apr 21, 2017
    Location:
    New York
    Here I am some two and a half years later back with a new build! I'm about to start a 5F2A build and in preparation I've done some drawings to help me figure out the wiring for the transformers. That's always a difficult area for me so I hope someone can let me know if I got the wiring right! I know this might look confusing, but I'm very visually inclined and this diagrams help me a lot in my process. I hope it makes sense!
    I'm using classic tone 40-18031 and 40-18085
    6994434E-43F3-4900-9A3A-0DA689B36A9E.jpeg E0176E67-9D99-4F44-A97A-C3BD1990D20B.jpeg
    Thanks in advance!
     
    ScottMosesMurray likes this.
  2. Pooks

    Pooks TDPRI Member

    Age:
    45
    Posts:
    19
    Joined:
    Oct 26, 2019
    Location:
    Boulder, CO
    I'm no help on the schematic, but I just wanted to point out that the light is the perfect brightness.
     
    Red Planet, bhenry83 and SebC like this.
  3. dan40

    dan40 Tele-Afflicted

    Posts:
    1,475
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    For 120v wiring, everything looks good except the primary side of the PT. You need to join black and brown together and run to the power switch. The brown/white and black/white will also be joined together and run to the white (neutral) wire from your power cord. The OT wiring looks good.

    http://www.classictone.net/40-18085.pdf
     
    SebC and King Fan like this.
  4. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    SebC likes this.
  5. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Also, if you have room in the chassis for an extra switch, you could use a DPDT ON-ON switch an utilize both the 630V and 550V HV secondary taps. Call it a Vintage/Modern Voltage switch.
     
    SebC likes this.
  6. Mongo Park

    Mongo Park Tele-Holic

    Posts:
    696
    Joined:
    Nov 28, 2010
    Location:
    Winnipeg
    You could connect the heater center rap (green yellow) to the cathode, pin 8 of the 6v6 power tube. This will give you the elevated heaters and is thought to reduce heater hum. Cheers Ron.
     
    SebC likes this.
  7. SebC

    SebC Tele-Meister

    Age:
    41
    Posts:
    253
    Joined:
    Apr 21, 2017
    Location:
    New York
    Thanks so much, I can see it now on that spec sheet. I’m still a bit confused on something: This is what I *think* I understand. From the primary side a lead goes to switch and the other goes to neutral of AC chord. In general, does it matter which of the leads of the primary goes where? I think in an earlier build I used a transformer where there was no difference. But I saw a thread on el34world where about my transformer here that said: 1) tie the black and brown together - this is the "neutral" lead.
    2) tie the black/white and the brown/white together - this is the "hot" lead.
    Where I’m still confused is does it matter where each lead goes? As per this and @dan40 answer, the “neutral” lead of the transformer primary goes to the power switch, and the “hot” lead goes to the neutral of the AC chord. Is that correct?
     
    Last edited: Dec 13, 2019
  8. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    I don't know if it really matters.

    Personally, I ran the brown and black wires to the switch and the black/white and brown/white wires to the mains neutral.
     
    SebC likes this.
  9. ScottMosesMurray

    ScottMosesMurray TDPRI Member

    Age:
    49
    Posts:
    11
    Joined:
    Dec 10, 2019
    Location:
    USA
    Go get 'em
     
    SebC likes this.
  10. drneilmb

    drneilmb TDPRI Member

    Age:
    112
    Posts:
    80
    Joined:
    Nov 30, 2019
    Location:
    Decorah, Iowa, USA
    It does not matter. The nature of AC voltage is that reversing the leads amounts to a phase change in the waveform. In this case, since there isn't any need for a particular phase relationship between two different AC signals, you can choose whichever phase you want. That said, if there is a wide-spread convention, you can follow it to make it easier for anyone else to understand and work on your amp.
     
    dan40, SebC and mabinogeon like this.
  11. SebC

    SebC Tele-Meister

    Age:
    41
    Posts:
    253
    Joined:
    Apr 21, 2017
    Location:
    New York
    Great! Thanks a lot!
    Really excited about this build. Been studying some 5f2a thread here and already gotten some nice ideas. Thanks to @theprofessor I ordered some bakelite chicken head knobs and will get the bakelite fuse holder. Also thanks to his thread I’ll add the diodes on the rectifier.

    I'll also incorporate @Mongo Park tip about the heaters center tap. Thanks! Every moment spent here is such a great opportunity to learn!

    Just as background on the build: I'm using a WGS G10C/S speaker and the cab will be made by Will at Armadillo Amps by John Mergili's recommendation since he says he isn't building cabs anymore.

    I got a small parts kit and chassis from mojotone but replaced all the caps and tube sockets.

    Can't wait to get started!!
     
    dan40 likes this.
  12. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Not sure which diodes he recommends, but those 1N4007 diodes everyone uses are just so tiny.

    I switched to using RL207 diodes, which are a 2A version and a bit easier to work with. I tried to use the 1N5408 3A, but it's too big.
     
    JohnnyCrash and SebC like this.
  13. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,031
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA


    I’ve been using those tiny diodes for years. Only recently I decided to go with the bigger ones.

    I never had any problems with them, but for what they do, I felt weird keeping the tiny ones in place.
     
    SebC likes this.
  14. SebC

    SebC Tele-Meister

    Age:
    41
    Posts:
    253
    Joined:
    Apr 21, 2017
    Location:
    New York
    This sounds interesting, what could be the expected change in switching to the vintage voltage?
     
  15. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    I thought I was clever and came up with this idea myself, but it turns out Dr. Z beat me to it with the Z-Wreck (and I am sure others as well. I'm not that smart).

    From the Z-Wreck manual:

    "Speed/Comfort Switch: Switches between two different plate voltages from the power transformer. Speed yields a strong attack with increased clarity and dynamic headroom. Comfort drops the voltage for a more vintage feel."

    I mean, you've got the taps - may as well use them, right?
     
    SebC likes this.
  16. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Same here. My clumsy fingers prefer the larger diode.
     
    JohnnyCrash likes this.
  17. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    95
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    If you're doing a modification or two anyway, I would also recommend adding:

    A 100KΩ 3W bleeder
    resistor to the first filter cap.

    Best-practice is to run the resistor from the + side eyelet to - side eyelet on the circuit board at the first filter cap (the one on the left) – but if the resistor’s leads aren’t long enough, it’s ok to just solder the resistor across the leads of the first filter capacitor.

    And

    A 470Ω 3W screen resistor and a 1.5KΩ 1W grid stopper resistor to the power tube socket.

    Take a look at your 5F2A layout and you will notice that pins 1 and 6 of the 6V6 power tube socket are unused. These pins have no connection inside the tube either, so you can use these pins to add the above resistors. In short, the wire coming from pin 5 is moved to pin 6, and the 1.5KΩ grid stopper resistor is soldered between pins 5 and 6. Likewise, the wire coming from pin 4 is moved to pin 1, and the 470Ω screen resistor is soldered between pins 1 and 4. Easy-peasy.

    Fender added these to their Tweed Reissue amps. I think they probably left them off their low-wattage Tweed amps originally as at the time they considered them entry-level practice amps.

    Here's a screen grab from the '57 5E3 Reissue service manual where you can see those resistors on the power tube sockets (and the diodes on the rectifier tube socket):

     
    Last edited: Dec 13, 2019
  18. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,031
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA


    It’s like a sort of Variac in a way. The Van Halen “brown sound” concept of running an amp at lower voltages to get a little more warmth/overdrive and looser feel.

    I’ve used a switch to drop voltage and I’ve also used stuff to vary the voltage drop on a pot/knob.

    Depending on the circuit and the voltage drop, the difference might be noticeable or subtle.
     
    SebC and mabinogeon like this.
  19. dan40

    dan40 Tele-Afflicted

    Posts:
    1,475
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    As the fellas mentioned above, either pair of primary wires can go to the switch and neutral. If you have a three terminal tag strip in your kit, you can attach one to the PT mounting bolt and use either the right or left lug to solder the power cord neutral and the two wires from the PT to. This will provide a better connection point instead of just soldering them together and heatshrinking them. You can also use the center lug of the strip for a convenient grounding point should you need one. The two outside lugs are not grounded to the chassis and make for a great connection point for those PT wires. Good luck with your build and post plenty of pics as you go along.
     
    SebC, JohnnyCrash and mabinogeon like this.
  20. SebC

    SebC Tele-Meister

    Age:
    41
    Posts:
    253
    Joined:
    Apr 21, 2017
    Location:
    New York
    Nice! I had been thinking a lot about how to solve that neatly and this sounds like the best way. Thanks! I haven't received the small parts from mojotone yet so not sure what is included on that kit.
    Might not be able to start building until the first couple of weeks of 2020 but once I start I'll be sure to post lots of pictures and ask lots of questions!
     
    dan40, mabinogeon and JohnnyCrash like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.