5G9 - Long time coming - begins

Discussion in 'Shock Brother's DIY Amps' started by Mr Ridesglide, Feb 14, 2020.

  1. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    image.jpg Tonight I wired up all the 6.3 VAC action. Checked the PT, no center tap so went ahead and put in an artificial CT.
    Not sure if anyone can see, but I like to put nylon bushings behind the switches so there are less threads poking out into my area of the world. Just the way I like it to look topside.

    Going to take a day or so off here to get a new hip put in tomorrow. Going in mid day but should be home either same day or Thursday. Hoping to be back at this some on Saturday when the Mrs. has to go to work, and she's putting babysitters in charge of me. Those babysitters I think I can handle.

    Suppose I can look this up somewhere, but do any of you have tricks to "clean" the fiberboard after all the soldering and flux splatter? Mostly it doesn't bug me so much, but when I take photos, or see clean examples here I sort of get wishing for better.
     

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    Last edited: Feb 25, 2020
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  2. King Fan

    King Fan Poster Extraordinaire

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    That looks great.

    So you're going to renew your hipness? Best of luck -- may you wake up dancing with a beautiful nurse in the recovery room before you even know you're asleep.

    Sometimes my switches come with little 'depth collars' you can adjust on the bushing to regulate the amount that shows. But that solution looks bomber.

    As far as cleaning fiberboard, I brush or spray with 99% isopropyl, 'scrub' thoroughly with an acid/flux brush, and drain/blot with paper towels. Repeat if needed. Some folks use purpose-built flux cleaners too. In both cases be careful -- solvents can lift some component labels. (F&T, I'm looking at you.)
     
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  3. TobyZ28

    TobyZ28 Tele-Meister

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    I typically use 99% isopropyl alcohol solvent as well with a small paintbrush. This was super easy on the board outside of the chassis... I also found (by accident) that using a hairdryer will also melt down a lot of the excess flux (be careful it heats things up FAST in narrow chassis - don't want to damage any components). I think warming it up and then using the solvent and brush (and mopping it up after) would be very effective.
     
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  4. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Thank you TobyZ28. Can’t wait to try it out!!
     
  5. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Okay. Finally getting to spend a half hour at a time on the assembling.
    Wonder if the consensus here is that I could ground the 100k resister and Speed Pot ground here to the filter cap grounding at the foot switch for trem
    06C6EBE9-109E-46B2-B0A4-460181E08C92.jpeg
     
  6. jsnwhite619

    jsnwhite619 Friend of Leo's

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    I've always just gone off the back of the pot for anything that had it that way on the original. I run everything from V1 to the preamp node filter cap to the same input jack ground, the power/bias section to a single ground, then the center taps & power ground together. I'd say try it, and if you have hum or oscillation issues, maybe start there?
     
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  7. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Thanks Jsnwhite. I am probably over thinking. I had it on the drawing as going to bus on input jack side. Just the way it laid out in chassis got me thinking.
     
  8. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Heaters and lead dress placement have always been bigger problems for me than grounding. I always run the behind the board ground wire just because of the clutter. I tried a bus bar once and hated the way it looked and the space it takes up.

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  9. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    I like the hiding bus idea. Giving me an idea for the next time I get into something like this.
     
  10. King Fan

    King Fan Poster Extraordinaire

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    I agree about the bus. You said you saw the thread where I discussed the footswitch ground with @tubeswell, but I currently figure I'll try the bus and see how it sounds. So handy sitting right there.

    Jason has built way more amps than me. I like a visible bus bar tho -- easy to build in stages, easier to see and test and revise later. The trick is making it look decent and, in a Tweed chassis, fitting it below the pots and jacks. I find square tinned bus bar looks decent, and a couple solder lugs will hang it just in front of the board -- note input jacks...

    upload_2020-3-7_9-5-34.jpeg
     
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  11. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Getting pretty close now to the light bulb limiter section of our project. Opened up the box from Armadillo and I must say I like how the cabinet looks. Even shielded the rear panel for me. 25D41D5D-3AEB-4230-9086-D96850624ADD.jpeg 287ED445-B5C1-4137-9D92-3B54DE25C5C6.jpeg
     
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  12. King Fan

    King Fan Poster Extraordinaire

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    Really impressive progress.

    We future builders would love it if you could put up some step-by-step pics. You've clearly done a lot of planning and a lot of custom building.

    What is that heater wire, 12ga? ;) Or is it the double-insulated kind that looks like Nana's bucatini? The twists going to the sockets are *very* neat.

    Hope you're feeling better, my friend.
     
  13. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Ha. The heater wire has finally seen the end of the spool. I have used it up over the last couple years. I think I got it from Tube Depot. 50 feet and I thought it was 18 ga. I still have a bunch of red and yellow in 20 gauge. I didn’t use the red or yellow up yet, but thankfully I’m done with the green. Takes up way to much space; especially for a tweed style chassis. I really didn’t need to do so much custom work here, and didn’t document much of it. I layed the project out with Inkscape as I have the past few builds I’ve tried. I did drill the fiberboard and set the eyelets. I did open up the octal sockets and drill a few holes for the transformers and the fiberboard mounting nylon screws. One item that is a pain for me is when the PT doesn’t fit. I have had this happen before, and I really have never come up with the best solution. Going in now to see if I can make it work!
     
  14. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Okay. Works pretty good! All 4 inputs work as they should. A shade more voltage than I was expecting. Was able to adjust the bias with the resistor I chose to work with 10k pot. All good there. I am now rethinking the speed pot. It is a 2M audio. But I don’t think it’s a reverse audio pot. The trem is deep for sure; slams nice and hard. But- its fast. I get some interaction with the trem on the opposite channel even when pots turned down on trem. But I am able to find a sweet spot that is not pulsing on the opposite channel. I did not try jumper channels yet. Needed a hip break. Ice and elevation. Here is something I started doing a few amps ago when I learned an expensive lesson.
     

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  15. King Fan

    King Fan Poster Extraordinaire

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    Heh, good idea. And yeah, I’m sure your wire is 18ga. That TubeDepot stuff just *looks* like halibut line. And yes, I was wondering where you managed to find a 2M RA pot!

    I’m sure you’ll post some voltages when you get her dialed in. I’ll be curious to know what resistors you put around your 10kl bias pot. I’d love to go that route if you find it spans your adjustment needs.


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  16. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Plates of 6V6GT to Cathode about 390-395 depending on where I set bias.
    Same with pre-amp voltages. I think about 320. So I’m in that “modern” voltage range with the MM transformers. Now I have quite a few 5u4gb rectifiers I can try and they are 50 plus years old so probably solid as can be. Same with the tubes. I have quite a few NOS 6v6 tubes to roll. I’ll play some when I get up.
    So what to do about the 2M pot? I think I DO have 3M from Doug Hoffman. And I think I somewhere in this mess have some 2M to look for that I got on auction that “said” they were specifically for trem circuits. I’ll do some hunting.
     
  17. King Fan

    King Fan Poster Extraordinaire

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    Somewhere @tubeswell noted you could use a 3MRA pot (IIRC available at AES) if you upped the shunt resistor...

    upload_2020-3-8_14-41-17.png

    Good idea getting the 'low-voltage' version MM PT. I believe it's 320-0-320 while their hi-volt version is 350-0-350. If you have 390 at the plates *on modern power,* and schematic/notional is 370, that does seem pretty close to vintage.
     
  18. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Thank you King Fan. I found Tubeswell-isms on this site and others regarding this. Also find that without the better pot, most find that their range of effect happens later in the sweep. Mine is active at the very beginning of sweep and continues as it moves. My son will over for Sunday dinner soon and I’ll put him to work helping me get the chassis in and I’ll have him start breaking in the speaker. Lol. He loves to just jam away on these when they get working.
     
  19. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Hey King Fan. I forgot to tell you. The bias resistor with the 10k pot is a 48k. Makes sense and I think I’ve had this solution before. Original amp called for a 56k resistor. We just choose to adjust our fixed bias amps nowadays.
     
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  20. King Fan

    King Fan Poster Extraordinaire

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    So your resistor before the pot is the stock 82k, and instead of the 56k 'tail' resistor, you have a 10k pot and a 48k resistor? Sort of like 48k + 10k = 58k? Almost too logical!!! :)
     
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