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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

First 5F1 build Question

Discussion in 'Shock Brother's DIY Amps' started by sirnoel, Dec 5, 2017.

  1. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    Hey scrappers and moders.

    I am putting together my fist build. Doing a Champ style amp with the MoJotone small parts kit and some salvaged stuff from an old Magnavox console. I am using the Magnavox chassis and although it's bigger than the champ Chassis it isn't laid out for an eyelet board.

    IMG_3744.jpg

    I'm going to punch out the front and put the controls there but I would have to mount the eyelets so that they overlap the tubes like this:
    IMG_3745.jpg
    Any problems with this plan? Provided I can keep the components from touching. Anyone got a better idea?

    Here is a closer look at what I'm working with.
    IMG_3746.jpg
    This is just the begging so thank you for your help now and in the time to come.
     

  2. rocksmoot

    rocksmoot Tele-Meister

    159
    May 6, 2012
    Rogers, Arkansas
    I just re-purposed a solid state amp chassis for a 5e3 build so I have a soft spot in my heart for the kind of thing you're doing. It's hard to visualize what you have in mind because you don't really say what part of the chassis you consider "the front." Consider drawing a to-scale layout on paper (or with visio or some other tool like that) so you can see how it would work before you start cutting metal.

    As far as overlapping, that's no problem if you have good clearance. Modding or repairing later might be a bit of a pain, but it should work. They make nylon standoffs of many different heights, I'm sure one of those will get your board up in the air high enough.

    Also, you don't necessarily have to use the eyelet board, you can use tag strips to make things a bit more compact or fit in ways that are awkward for an eyelet board. Still, if it's bigger than a Champ chassis, I can't see why it wouldn't work with the board.
     

  3. corliss1

    corliss1 Tele-Afflicted Gold Supporter

    Sep 13, 2008
    Lansing, MI
    Overlapping is fine as long as there is clearance. Are the tubes going to be vertical like a tweed/blackface style or are they going to point horizontally in toward the amp? If horizontal RCA has recommendations about the orientation of the tube's pins that you can check the tube data sheets for, although I'm not sure how many people actually pay attention to that stuff.
     

  4. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    The plan is to lay it flat on the bottom of the cab with tubes pointing up and all the inputs and knobs facing out, accessible from the back of the cab. My plan is to drill holes in the shorter undrilled side that is at the top of this picture.
    IMG_3746.jpg
     

  5. corliss1

    corliss1 Tele-Afflicted Gold Supporter

    Sep 13, 2008
    Lansing, MI
    If the tubes are pointing up then you don't have to worry about anything. Carry on :D
     

  6. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    That looks like it would be a pretty good candidate for point to point. Just sayin'

    But at the very least I'd suggest you reconfigure your circuit board a bit differently. The 5F1 board is designed to route signals from point A to point B assuming point A is the upward facing face of the amp and point B is the downward facing face of the tube sockets, with detours planned for the PT, lamp and power chord. With your chassis configuration you could probably redesign the board in a way that makes more sense with what you've got rather than Leo's tweed chassis. Make sense?

    This all seems like it will greatly complicate your build, but just remember that you are going to be building this amp for a little while, but playing it for years.
     
    Last edited: Dec 6, 2017
    jtcnj likes this.

  7. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    Alright. You convinced me, I am going to P2P it. It's already got some terminal lug strips installed and I have a few more I can put in.

    Here is how I've laid out the jacks and tube sockets.
    IMG_3782.jpg

    I am pretty familiar with the 5F1 Schematic at this point so I'm going to use that as my guide. Does anyone have any diagrams or good pictures about how people have done this circuit point to point before? I have watched Uncle Doug's video on this but he mostly covers mods and doesn't show the wiring much. Most of the Internet searches are pictures of the Champ 600.
     

  8. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    Right after I posted my comment, I watched this video.


    And I've been sketching stuff out just for my own benefit. But I think you are absolutely right to just let the schematic guide you. I wish this guy talked more about how and why he separated his filter caps. As you can see, his first filter cap lives right next to the PT and the other two are paired on the input side.


    PS: Sorry, skip to 5:45 to get to the actual circuit.
     

  9. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    This is helpful for sure. In my current layout I had all my filter caps grounding to the same point. Is that a bad idea? I could run the first one to another lug strip and connect that to a separate ground.

    He seems to like giving each a separate ground point.

    I got a drawing, looks like a rats nest. But I will post pictures once I get it all together for folks to look over.
     

  10. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    I used RobRobs 5f1 page to inform my grounding scheme and I also worked really hard to limit the number of grounding points to 3 (I thought that was a huge achievement).

    RobRobs page suggests the first two filter caps should be grounded to the power side along with the power tube cathode and its bypass cap. But the pics of P2P Champs that I've seen appear to show they weren't that concerned with the number of grounding points. And you'll note in this video he's apparently grounding the second and third cap to the input side and the B+1 cap has its own ground near the PT. I liked the YouTube video's mention in passing of keeping grounding circuit within their own "loops." Not ground loops, but circuit loops.

    Yeah, the ideas I've sketched out benefited from being edited more than once. My first was a rats nest, but it gave me ideas to clean it up. But this was done just for fun while on breaks and lunch so its a long way from done, or even correct probably.
     

  11. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted Silver Supporter

    Dec 11, 2009
    Bloomington, MN
    IMG_6262.JPG
    Here is one that I did with a similar situation. You still will want to keep aware of where you ground the different grounded components.
    Great project you have there! Popcorn stocked to watch you do it!
     

  12. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    Yep, that's P2P. Nice! It looks like your pots and inputs are in a separate compartment from the tubes and transformers?

    And obviously the champ won't have wire runs nearly as long. Wow, I'm kinda excited to watch your 5F1 build thread. Should be cool.

    To the OP, you're probably all over this already, but don't forget Hoffman's site and AmpGarage. Those might have some good discussions and or pics and schematics for P2P Champs. You're right, the Internet has almost nothing on it. Thanks for nuttin' Al Gore!


    http://el34world.com/Forum/index.php?topic=21418.msg227240#msg227240
    Some interesting discussion on P2P, but make up your own mind about whether using a terminal strip to aid your layout disqualifies it as P2P (eh, whatevs).

    Also sage words from a total stranger that I've never met giving Internet advice:
    "From what I gather, what makes point to point feasible is an underlying knowledge of how signals will interact with nearby components and armed with this knowledge, the builder, when routing the connections, does so in an electrically compatible manner. It is an Art-form. If your interested in pursuing it, make it a beautiful thing and take into consideration the near field interactions between sensitive components. This is what the "Old Masters" understood.

    silverfox."


    With a handle like "silverfox" we should assume he's old and therefore right.
     
    Last edited: Dec 7, 2017

  13. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    That's inspiring. Though it certainly doesn't describe the work I did tonight. Here it is for your inspection.

    A lot of my choices were based, unfortunately, on where lugs already existed. They are grounded to the chassis with big globs of solder that my budget iron just can't get up, so there they stay. But everything at least connects to what it should. I think.


    IMG_3784-2.jpg
    IMG_3788-2.jpg IMG_3789-2.jpg
    IMG_3787-2.jpg IMG_3786-2.jpg IMG_3785-2.jpg
    Pretty messy, and all those untrimmed leads don't help matters, but I wanted to be able to undo anything based on your thoughts. Or just sleeping on it and thinking better of it in the morning. Unsoldered and waiting for a 2nd draft.

    What are you seeing?
     

  14. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    Hey, Mr. Ridesglide, what kind of shrink wrap is that on your resistor leads. With all the overlapping I'm doing I need them as clean and insulated as your are.
     

  15. corliss1

    corliss1 Tele-Afflicted Gold Supporter

    Sep 13, 2008
    Lansing, MI
    Looks like regular heat shrink to me.
     

  16. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    Confirm the ground and connection lugs on your terminal strips. My 3 eyelet strips have the ground terminal in the middle. Don't want the wrong connection going to the chassis. Also I wouldn't attempt to solder directly to the chassis. Better to use a bolt and terminal ring. Especially if as you say your soldering iron is underpowered.

    Also make sure heater fils are away from signal wires. But dont worry too much about this until its running and you find unwanted noise.

    IMO, try your best to keep your ground connections to a minimum if possible. If it's noisy, that may be a reason. Also, familiarize yourself with this article, particularly star grounding. http://www.aikenamps.com/index.php/grounding
    Not suggesting you do it, just good info to know.

    Your photos are way better, thank you. But as you can imagine, this is challenging to sort out from pics. But I'll study it and I'm sure others will too.

    I sometimes use discarded wire insulation to cover some component leads. If it fits it works. 20 AWG or larger seems to be the right diameter.

    Final point. On my build I fired it up as soon as the PT, lamp, heaters and fuse were wired. I made sure I was getting ballpark voltages on my rectifier and my lamp voltages were good. Plug it into current limiter and if it doesn't explode (ha) I plugged it into the wall. Seemed to help when I finished and started the inevitable troubleshooting phase. Just a thought. If its too late here, it's ok.
     
    Last edited: Dec 8, 2017 at 12:15 PM

  17. sirnoel

    sirnoel TDPRI Member

    26
    Feb 21, 2012
    Chicago
    That's a good idea. Particularly as the PT is a salvaged piece.

    I double checked the eyelets and grounds, sorry they are not always apparent in the pictures. I have a ground for the power chord and center tap of the OT. A ground for the preamp cathodes. A ground for the the 3rd E filter cap, and the grid leak resistor for the power tube. And a ground for the power tube cathode and the first 2 E filter caps.

    Looking at Rob Rob's site I will move the C5 ground to the pre-amp and R9 to the power ground.

    gonna go work on slapping together a cab while people take a look

    Thanks so so much for your interest and help on this. It's been more fun than frustration. So far.
     

  18. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    Ok, first off I'd remove the solder from the terminal strip to chassis and replace it with a bolt nut and lock washer. Use a solder sucker and or soldering wick, but get that gunk outta there.

    Also, where is your V1A bypass cap (25uf on preamp to ground)? I see the power bypass coming off the 6V6 socket, and I see the 1.5M resistor coming off the 12ax7 socket, but not the cap.

    I don't see an filament center tap. I did an artificial center tap by running a 100 ohm resistor from each leg of the filaments on the 6V6 to cathode. So, one leg of each resistor to pins 2 and 7 respectively and both end at pin 8. That elevates the ground. You can just as easily attach a resistor to each lug of the lamp and ground them to the chassis somehow. Your call. My way is theoretically less noise, and I believe it based on a sample size of exactly 2 amps.

    Your B+ power caps look good but I'd feel better about getting B+3 as far away from the PT as you can manage. Maybe run a wire from the dropping string to the far lug and take the filter cap off of that and on to the plate load. Also in the final assembly you should consider some stable mounts for your larger components like filter caps. Even if they're on a bed of silicone attached to the chassis, its at least something.

    With this build, with a PT that you aren't so sure about and with a P2P that is new territory to you, I'd consider some equipment-saving ideas. Soft fail rectifier diodes might be a good option here just in case. I would make a visit to this page and read about protection mods. And of course, you've got either a Variac or a Current Limiter? Variacs can be had fairly cheaply these days, current limiters can be built with the pocket change you find in your couch, ha.

    Mr Ridesglides P2P looks really clean. I'd steal ideas liberally from him before you settle on a final layout.

    I also think that you would be doing yourself and the Western world a favor by being disciplined about wire color coding. Make signal wire one color, supply wire another color, ground wire still another color, and so on. Just makes it easy to follow if you have to open it up a few years down the road. I'm exhausting my limited knowledge and looking forward to the smarter guys weighing in now.
     
    Last edited: Dec 8, 2017 at 12:58 PM

  19. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    Very late in the game to be doing this, but what are the specs for your transformers? If you don't know, its essential to find out before you power up anything.

    You mentioned the PT was a salvage, I was slow in picking up on that. Sorry
     

  20. JuneauMike

    JuneauMike Tele-Afflicted

    May 5, 2015
    Alaska
    Hmm. Don't think my idea is any better than what you've got, but it was fun playing with the puzzle pieces.
    ptp.jpg
     

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