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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

6G2 build begun

Discussion in 'Shock Brother's DIY Amps' started by King Fan, Oct 21, 2017.

  1. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    In case there's anyone on TDPRI who hasn't already pitched in to help with my research on this project...

    I finally started!

    I wanted to use the Mojo chassis, but found out it had the wrong sized PT cutout for standard PT, and the wrong holes for the fuse and power input. So I ordered a great Alu chassis from Seaside Music. They punch the big holes but I knew I could make the smaller ones -- especially in aluminum. Used the faceplate as a template -- see scribes in background.

    6G2 - 1.jpg

    I decided not to go with a cap can -- quieter grounding options -- and so spent some time trying to figure out the best way to orient three filter caps in that space.

    6G2 - 2.jpg

    What I didn't quite count on was exactly how many holes it takes to fill the Albert Hall. :D This is another important term in the equation comparing cost / time / DIY enjoyment with a full kit or complete chassis. Someday I'll count them all.

    6G2 - 3.jpg

    Hey, alu is a lot softer than steel! I have a nice Irwin step drill, and on steel each step is highly separate and distinct. On aluminum? Not so much. After one hole got too big, I found blue tape is your friend:

    6G2 - 4.jpg

    The backside holes went better, but more drama lurks in the wings...

    6G2 - 5.jpg
     

  2. jsnwhite619

    jsnwhite619 Tele-Afflicted Ad Free Member

    Sep 10, 2013
    Georgia
    Glad you got the ball rolling! I'll share a couple of tips I've learned with drilling/punching a chassis. Keep a shop vac handy for all the pieces of metal that fall on your bench & floor while you're drilling and to clean out inside the chassis. And if you drill a hole too big - I think I did for the pilot light on my 5e3 - I found a washer that I was able to drill out a little more and make it work. I bet aluminum is a lot easier than my 5e3 blank -- 16 gauge galvanneal was rough back before I had a drill press! My batteries were getting too hot to charge!
     

  3. jsnwhite619

    jsnwhite619 Tele-Afflicted Ad Free Member

    Sep 10, 2013
    Georgia

  4. CoyotesGator

    CoyotesGator Tele-Meister

    309
    Jul 12, 2014
    Gulf Coast
    Popcorn, must have popcorn!
     
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  5. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Great stuff, Jason, thanks. Shop vac indeed!

    And that eBay source looks excellent.
     

  6. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    OK, it's not exactly drama, more like another episode of the King Fan Comedy Hour. :D

    Besides the oversize PT cutout in the Mojo cab, I didn't like having the fuse hole actually cut for a strain relief -- what I've seen called a double-D shape. (For details and pics, see this great thread by Fender-meister @keithb7)

    So I had Terry at Seaside put an IEC cutout in the ever-traditional far left rear of the chassis. What could possibly go wrong?

    Well, eventually it dawned on me that IEC plugs stick out from their sockets. A lot. Even the right-angle ones. Enough that they absolutely don't fit under the top back panel of a 6G2. Oops.

    So I crafted a plate to cover my IEC cutout, and figured out how to drill a hole to fit the strain relief. Of course I tried to find the specs for my Heyco 6N-R strain relief (I *think* the standard Fender size). Heyco has technical drawings out the ying-yang, but somehow the drawings made me think I needed a 9/16 hole. No joy -- square peg, meet round hole -- so after an hour of repeated Dremel torture, I got something kinda double-D that fit.

    6G2 - 1 (2).jpg

    Later, just after I was all done, I *then* saw where Doug Hoffman points out this SR will fit just fine in a 5/8 hole. Well, fine then! But hey, mine at least can't rotate -- like in case I swing my amp over my head by the power cord. :)

    So my long day's journey from strain relief to IEC ended up back at strain relief.

    The happy ending? I had just ordered some $11 strain relief pliers from Amazon (Pro'sKit, if you're looking).

    Even in my lame cutout, these turned the usual 20-minute plastic-mashing swear-fest into 2 seconds of effortless bliss.

    6G2 - 1 (3).jpg
     
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  7. jsnwhite619

    jsnwhite619 Tele-Afflicted Ad Free Member

    Sep 10, 2013
    Georgia
    Yeah, I figured out that you can make them work with a round hole, but I think I just beat you for wasted time spent on strain relief mounting. I've always used a pair of channel lock pliers to do it - along with lots of cussing and usually a scraped finger or two. In looking at your pictures and finally getting a good look at the strain relief pliers, I just realized that I have a pair my dad gave to me YEARS ago in a box of random tools. I never knew what they where! :rolleyes:
     
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  8. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    :lololol: Misery, here’s company! Send me your bill...
     
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  9. Nickfl

    Nickfl Tele-Holic

    680
    May 24, 2016
    Florida
    I have bought Princeton reverb chassis from him twice in the past and been very pleased. I will be buying from him again for my next build (which ironically will be the first of the three which will be used for an actual Princeton...). I've also used this seller: https://www.ebay.com/usr/synapticamps?_trksid=p2060353.m1438.l2754 for a blank chassis for my most recent build as his price was better for a blank square chassis in aluminum and he will do them to any specified length up to 22" at no additional cost.
     
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  10. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Heh. So I'm seeing I should have asked even *more* questions before starting -- like where to get a 6G2 chassis. This is why the amp forums here are infested with my amp-planning questions. :)
     

  11. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Transformers in hand:

    6G2 - 1 (4).jpg

    And in place:

    6G2 - 2 (1).jpg

    Time to wire up the household mains. The black was cut long enough to reach the fuse, and the green somewhat longer than that. The white needed a tie point, so I cut down a 3-lug terminal strip and mounted that near the safety ground down in the 'power corner.'

    6G2 - 4 (1).jpg

    I finally figured out that Fender lamp assemblies fit better lying on their side, and also noted the originals had a piece of fiberboard under the lamp to prevent grounding out.

    6G2 - 3 (1).jpg
     
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  12. CoyotesGator

    CoyotesGator Tele-Meister

    309
    Jul 12, 2014
    Gulf Coast
    FWIW, I solder on my lugs instead of crimping them.
     
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  13. dan40

    dan40 Tele-Holic

    612
    Aug 19, 2015
    Richmond Va
    Which set of PT secondaries have you decided to run? I chose to use the lower set with my 6g2 and it gives me right at 315-320vdc with a 5y3. IIRC, the higher set gave me around 350-360vdc but I think the amp sounds better and breaks up a touch earlier with the lower voltage.
     
    King Fan likes this.

  14. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Thanks. Good question. Despite a number of threads noting the low scheme voltages weren’t actually achieved in vintage amps, I’ve heard many folks like you endorse the lower set, and I like their reasons, so that’s what I’m doing.
     

  15. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Yes, many folks do. Tech sites, though, note crimping, done right, actually creates a molecular metal amalgam. I do solder over the crimp... because shiny.
     
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  16. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Horizontal fit best. Usually I put labels right side up so I can read 'em, but in this case it makes sense to have the + ends of the caps near the board and the other end near the grounds.

    IMG_0041.jpg

    Besides, the gold lettering on F&Ts is so fragile, it doesn't usually survive my 'repeated fitting' build process. And don't even show 'em a bottle of isopropyl...

    Next, built the input jack array using the outside of the chassis as a jig. Doug Hoffman points out that just because the drawings show the 1M inside the prongs, you don't *have* to mount it there.

    IMG_0047.jpg


    The EQ controls are simple on a 6G2, but it's still easier to build on the outside of the chassis, too. Here's the result.

    IMG_0053.jpg

    Finally, time to start putting things on boards. Little boards...

    IMG_0052.jpg
     
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  17. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Various steps with forum assistance.... A useful discussion here helped me improve my grounds on PT bolts (outside toothed washers on the bottom, Keps nut on top). Later the bias ground will go here too, and I'll add some Loctite.

    IMG_0054.jpg

    Following a discussion about testing during builds, I confirmed the household wiring, switch, fuse, lamp, and PT work.

    IMG_0048.jpg

    I was reminded about how to test film caps for outside foil end.

    IMG_0049.jpg

    And I found that a tedious step in my builds, drilling out the input holes for isolating washers, is easier with a plastic faceplate. :)

    IMG_0051.jpg
     
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  18. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    First, a shout out to @keithb7, whose vintage and homebuilt 6G2s got me interested in this project, and who pitched in above and beyond the call of duty from the beginning with advice and all sorts of generous support.

    Now, back to the boring details. Here's the bias board in place. You'll also see that the export / dual-voltage PT means lots of wires.

    IMG_5593.jpg

    Bias pot wiring -- we want to make this fixed bias adjustable. I followed Doug Hoffman's clear helpful plans. I've found it's helpful to put the bias adjust pot on the back panel. Here's the pot. It's hard to find an angle to see the lugs, but for connections to the pot, I just do what Doug shows.

    IMG_5633.jpg

    The two wires come from up front, as seen in this photo. I also pre-wired the rectifier with diodes and the power sockets with resistors.

    IMG_0059.jpg


    Finally, I've always found it tricky to check that back-of-board wires go where they should. The layout shows them as dotted lines, but if you flip the board, you see a mirror view that makes tracing the dotted lines against the layout hard. Although a 6G2 has few backside wires (many less than a Champ, tellingly), I still found I had one the wrong way. How? I took a pic and flipped it left-right in a photo app. (Rotation won't work.) Note the mirror-image here -- see the written notes? Now the layout lines up with what you see. Hint: my boo-boo involves the longest wire in the center.

    IMG_5622.jpg
     
    Last edited: Oct 26, 2017

  19. keithb7

    keithb7 Friend of Leo's

    Age:
    46
    Jan 9, 2010
    Western Canada
    I am patiently waiting for this fine amp to come together. Don’t rush. Savor every moment. I bet it’ll look and sound great.

    @King Fan I smiled at at the sight of your under-the-board wiring. It reminds me of some of the times I struggled with amps. Troubleshooting to find a problem under the board. Arrgh!

    You just sweat, all the time in denial as you check and recheck topside connections. “It’s gotta be on top. Gotta be. I’ll keep searching. Surely the problem is not under the board.” More than once, yes I had to at least partially re-lift the board.

    Thanks for the shoutout. I’m here lurking. Watching this great amp come to life! Keep the updates coming. We’re all loving ‘em.
     
    Last edited: Oct 26, 2017
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  20. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Thanks, Keith. Good advice — I hear you on the zen thing. I start all slow and careful. But right about now I get a crazy urge to push through and get done. Time to slow down and savor. :)
     
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