Building a 5f1 and a 5e3...

Discussion in 'Glowing Bottle Tube Amp Forum' started by Bergy, Mar 25, 2020.

  1. Bergy

    Bergy Tele-Holic

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    With all this time on my hands I am building my first two amps. I started out working on a Boothill 5e3 a while back but realized I was going to make some rookie mistakes that might make me think twice about taking it out to gig. To hopefully improve the quality of that build, I got a Franklyn 5f1 kit to practice on for a house amp. It came today and I just finished populating the board with the small parts. Now I've got a bunch of questions....

    IMG_5491.JPG

    So on the 5e3 up top... I've manhandled all the leads because I redecided to wrap them around the turrets as opposed to poking them in the top hole. I didn't do that with any filter caps because it would have them laying against the board. I've read that having components resting against the board is not a great idea. Is that equally true for both caps and resistors?

    I originally messed up the grounding on the preamp side of the 5e3. I went back and elevated that ground so that it runs about a 1/2 inch above the turrets. Hopefully that is sound?

    On the 5e3 I had a hard time getting that little resistor to maneuver around the top corner of the last filter cap. I reckon running that lead at a right angle would be a better option but it seemed like it was a little too short to get it to run at a neat angle.

    I've noticed on both builds that the leads on some of the resistors, especially ones that are placed with caps, are really short. I tried to remedy that on the 5f1 kit by wrapping the resistor to the leads of the cap (like with the 25uf on the right side and with the big ol 5 watt one in the middle). I only did one full wrap around the lead of the cap and cut the extra length from the resistor's lead. I've seen some people wrapping the entire lead multiple times. I guess multiple wraps would hold the resistor better prior to soldering...

    On the 5f1...I had a hard time making space in the middle of the board, specifically in the area around that white 5w. Is the crowding of those components going to cause problems?

    The other question I had on the 5f1...those voltage dropping resistors at the bottom of the filter caps...I've got that first one pressed right up against the turret and the lead from the 2nd resistor is actually touching the body of the first resistor. Could that cause problems?


    Thanks,

    Bergy
     
  2. muchxs

    muchxs Doctor of Teleocity

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    I use 1/4" foam rubber blocks to space the bias resistor off the board. I keep the screen grid resistor off the board. Everything else can be in contact with the board.

    That's the way Fender did it.

    Edit: Fender did it with most of their parts touching the board including a very small minority of parts that shouldn't touch the board.

    I remove my foam rubber spacers before firing up my amp. Burning rubber belongs at the drag strip.


    Here is an eyelet board I yanked out of someone else's 5F1 I tidied up. It worked fine even though it's lacking feng shui.

    IMG_1953.JPG

    It's probably a Weber VST board with upgraded parts. The caps are mostly Sprague.

    I think it's easier to do a tidy eyelet board than it is to use a turret board for your first try. There's no fiddly unwrapping leads if you make a mistake.
     
    Last edited: Mar 26, 2020
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  3. King Fan

    King Fan Friend of Leo's

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    Yeah. Eyelets are also easier to fit in a tweed chassis, where all space (including vertical space) is so limited. If you don't want to buy new boards, at least make sure not to wrap more than 180°. Speaking of vertical space, your flying bus on the 5e3 will work electrically, but does it clear your input jacks?

    Resistors get hot. That's why you're right to worry about crowding, especially around the 5F1 white ceramic wirewound. Where there's horizontal space (cathode resistors, especially 5e3 power tube cathode resistor) separate them as much as you can. If you can't separate them horizontally, like on the wirewound, fly the cap 1/2" or more above the resistor -- or vice versa with small resistors. Although I said vertical space is limited, that's not true in the center of the board. And when installed in the amp, that vertical separation becomes horizontal, so air can flow up and around the flying component.

    No need for right angle bends -- diagonal is fine. As for that second dropping resistor, for heat reasons, many people have it hang over the bottom of the board instead of crowding up under the filter caps.

    A couple bigger-picture items if you like: 1) You might see if the mods would move this to the Shock Brothers DIY forum -- you might get more amp builders. If not, no worries, but 2) at this point I like your idea about building the simple amp first, so I'd leave the 5e3 build out of this build thread for simplicity and clarity.

    Final, grand, over-arching note: The build sequence (eg, board first, power last) we see on 98% of new builds is not the most helpful. If you want to test as you build, increasing both safety and likelihood the amp will work on startup, try the build sequence outlined by super-builder Steve Luckey in post #3 in this thread:

    http://el34world.com/Forum/index.php?topic=2376.0
     
  4. Telekarster

    Telekarster Tele-Meister

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    Cool man! I want to do this some day.... Kudos! Good luck!
     
  5. muchxs

    muchxs Doctor of Teleocity

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    Lotta guys save their pennies, start with a cheap kit when they have enough pennies.

    I build my own boards from scratch.

    It's cheap and cheerful to scrounge up a 5F1 board and then chase down the parts that are supposed to be on it. I almost don't need to take my socks off to count the parts.

    :cool: :cool: :cool:
     
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  6. dan40

    dan40 Tele-Afflicted

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    I also like to lay all components flat on the board if possible. The larger filter caps have a bit of weight and suspending them off the board could eventually cause their leads to break off. I do like to raise the 5 watt cathode resistor up a bit to allow some air flow around it.
     
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