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Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

New (and first) build: 5f2a Tweed Princeton

Discussion in 'Shock Brother's DIY Amps' started by theprofessor, Nov 2, 2017.

  1. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    For short chunks of 'ground bus' (e.g., to jumper the caps) you can just use the longer chunks of leads you've cut off components. I wouldn't use heavy bar or Romex gauge on the power section ground bus -- it's a lot harder to fit than that 22ga heater wire.
     

  2. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, @King Fan ! So here's what I think you're saying. I've also referenced @keithb7 's photo of his preamp bus in post #60 of this thread [EDIT: My note in red typeface should say "input 2"]:
    grounding wire.jpg
    Here is @keithb7 's photo from post 60:
    Keithb7_preamp_bus.JPG
     
    Last edited: Nov 7, 2017
    King Fan likes this.

  3. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    I think you've got it, Professor! Keith's build is a good reference -- note how his tone pot's cap to ground goes back to the preamp ground bus.

    Not everything in your right hand oval gets grounded, of course, but you can use the schematic / layout to figure out what does. Triple check -- missing a ground or grounding the wrong thing is a "usual suspect" in troubleshooting threads.

    I want to complement our new builder @r_o_b_s_o_n who did a nice job on his 5F1 board -- see his pictures on about page 4 for a Romex-style ground bus. You'll also why I said a 5F1 is microsurgery...
     
    r_o_b_s_o_n likes this.

  4. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    As I get closer to finishing the eyelet board, I'm thinking on how best to mount it in the chassis. I have two questions related to parts in the Mojotone kit:

    (1) The kit came with a plain piece of fiberboard and the eyelet board. Does the fiberboard go in behind the populated eyelet board as a kind of buffer between the leads on the back of the eyelet board and the chassis? Or is this plain piece of fiberboard just something put in the kit to reinforce the eyelet board in shipping, in which case the populated eyelet board screws directly into the chassis so that the leads on the back (and possibly the solder joints, too) are touching the chassis? [sorry, I don't know why the pictures are flipped in different directions; I also realize that the eyelet board won't be mounted this far over to the right; this is just for the purposes of illustration]
    IMG_9440.JPG
    IMG_9441.JPG
    IMG_9442.JPG

    (2) Second question: The Mojotone kit comes with 2x 3-lug terminal strips. What are those used for?
    IMG_9443.JPG
     

  5. Outlaws

    Outlaws Tele-Meister

    157
    Jan 16, 2007
    None
    It’s the insulation so the board does not ground out. Use it like you first thought.
    The terminal strips I assume are for you to use as ground points.
     

  6. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, Outlaws! That's what I thought it was. I appreciate it.
     

  7. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Yep, Mojo uses those for ground points. Many builders omit them. If you do use ‘em, note only center lug is grounded without jumpers.
     

  8. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, all! How do y'all normally mount in the backing board before installing the eyelet board on top of it?
     

  9. keithb7

    keithb7 Friend of Leo's

    Age:
    46
    Jan 9, 2010
    Western Canada
    Lay boards together and line up. Ensure there is a hole through both boards, lined up. Put a fastener of choice through both boards and hole in chassis. Tighten down.

    I like plastic fasteners here. Small plastic bolts and nuts available at Home Depot for example.
     
    Last edited: Nov 8, 2017
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  10. D'tar

    D'tar Tele-Holic

    949
    Jan 11, 2013
    WNY
    I like plastic here also. I use these with success. YMMV

    car-trunk-cover-panel-universal-7mm-hole.jpg
     

  11. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, all. So it sounds like you simply mount the top board and the bottom board at the same time. I've got to figure out how to "float" the boards a bit, since they've got to go over the keps nut that holds the OT on. Maybe I'll put some kind of nylon spacer under there or something.

    Speaking of the OT: mine has a 4-ohm (yellow) and an 8-ohm (green) tap. I'm going to use the 8-ohm one. Do I simply leave all three (black, green, and yellow) coming through the right side twisted/braided together and then just cut the exposed tip of the yellow one and let it sit there? Or does it get special treatment, like being tucked away some place, with a wire nut and heat shrink?
     

  12. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

    Jan 2, 2007
    Virginia, USA
    No need for a wire nut. Heat shrink or electric tape should be used, however. Last thing you want is a short or arc.

    If you used some nylon spacers, you could probably go the same rout @Keith uses of nylon nuts and bolts from Home Depot.

    The vintage amps, and a lot of builders, just use a sheet metal screw through a hole drilled through the two boards and the chassis.
     

  13. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, Axis29! I'll put some heat shrink over the 4-ohm wire. As for the spacers and nuts, I'm fortunate enough to have a local hardware store (owned by a friend of mine) just about right across the street from my house. So I'll head back over there this evening to get some suitable nylon nuts and bolts out of their specialty bins. I've already been by this morning to buy some 14-2 Romex to get the copper out of it for a preamp bus, like @King Fan suggested.
     

  14. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    That OT bolt is too bad -- hmm, is there a way to mount a flush nut inside the chassis... Dunno. You might ask at the hardware store about 'weld nuts' with mounting holes -- although I have no idea if you could mount them almost flush or if they come in small sizes. Something like this the size of your OT mounting screw:

    Weld-Nuts-Tee-Nuts-Round-Base.jpg
     

  15. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, King Fan. That's a good idea, too. I'll look into it.
     

  16. tubeswell

    tubeswell Friend of Leo's

    Jul 1, 2008
    NZ

  17. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    BTW, re the Romex, I used it on my first build and have since wondered about a few things:

    If you have some to play with, try the straightening method Tubeswell mentions -- I don't know if it will straighten or 'take the twist' -- but straight is nice.

    Clean it thoroughly with 100% isopropyl before soldering.

    Then tin the area you're going to solder to.

    I wonder. Would it be possible to tin a whole length using a home iron and solder? Untinned it will get dark and tarnished between the solder joints. Oh, the horror. :D But this shouldn't affect function.
     

  18. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    I'll give it a try tonight--tinning a bus bar. I must confess that I like the incense-like smell of the solder, even though it's harmful. There's gonna be a lot of incense when I tin a whole bus bar! Interesting about cleaning it with isopropyl. I'll do that.
     

  19. RLee77

    RLee77 Friend of Leo's

    May 15, 2016
    Silicon Valley
    Just rub it down with like 800 grit sandpaper... nice and shiny new.
     

  20. keithb7

    keithb7 Friend of Leo's

    Age:
    46
    Jan 9, 2010
    Western Canada
    That's all I do too @RLee77. Sand paper, and its good to go. Solder flows on it like tone from a Tweed Twin.

    Personally I don’t think its a deal breaker to have a small OT nut under a fibre PC board. The board needs not lay perfectly flush to the chassis.

    See my buss bar image above. One PT nut is under the board too. See the white/jaundice colored plastic bolt head head holding the board down? Works just fine.

    I tried to get Pete Townsend to tour with my 5F2A, but he won’t return my calls. So it the amp mostly stays home. I figure its rugged enough being as Pete won’t be kicking it over at shows. ;)
     
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