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#pennypincher 5e3p 'X' -- first timer; amalgamated "kit"... DIY info

Discussion in 'Shock Brother's DIY Amps' started by ecoast, Mar 1, 2017.

  1. ecoast

    ecoast Tele-Holic

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  2. robrob

    robrob Poster Extraordinaire Ad Free Member

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    The jumper between the ground and shunt is necessary but the extra green ground wires are not needed unless you insulate the jacks from the chassis. They will form an unwanted ground loop.
     
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  3. ecoast

    ecoast Tele-Holic

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    thanks Rob; i am going to follow your grounding scheme.


    Can I use stranded 18 gauge for heater wiring?

    Or is it better to use solid 20 gauge I have on hand?

    Or?
     
  4. SacDAve

    SacDAve Poster Extraordinaire Silver Supporter

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    Hears a pic of how most people wire the inputs, this my be better for your first Amp. Hopefuly someone might post a drawing of the input wiring. Don't no why it posted two pics both the same DSCN0850.JPG DSCN0850.JPG
     
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  5. ecoast

    ecoast Tele-Holic

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    ^^thanks Dave; there is a good diagram on Rob's site; but as it was a diagram, just wanted to check to be certain.


    Read/searched a bit; looks like I'm ok using 18g stranded for filament heaters; perhaps a little unwieldy and of course I'll look out for loose strands...maybe a dollop of hot glue to hold heater wires tucked out of way.
     
  6. ecoast

    ecoast Tele-Holic

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  7. SacDAve

    SacDAve Poster Extraordinaire Silver Supporter

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    I orientate the foil on mine, but most people don't. SoZo's are marked but most are not. There is a simple tester you can make kind of irritating video. Pic of vintage 5E3 line is outer foil. I mark mine with a line around the cap. If you do make a foil tester I would suggest using a plastic box. I've built 5E3's without knowing the foil orientation I t's kind of a debatable thing, I just built the tester one day for fun and figure what the heck.
     

    Attached Files:

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  8. ecoast

    ecoast Tele-Holic

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    thanks again; I appreciate your help---

    I'm too lazy to pull them all out, so I will assume polarity is not an issue on these like the electrolytics?

    hoping I can 'let it ride' ?



    painted inside cab & parts that will show after covered with tolex:

     
  9. ecoast

    ecoast Tele-Holic

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    to continue:

    5e3p shows V3/V4 pin 8 to ground
    5e3 standard shows V3/V4 pin 8 to bias resistor



    I was intending to build as 'stock' 5e3 (excepting 40uf caps, 10w bias resistor, larger x-formers) and am wondering (with my limited knowledge) if I will have to change
    pin 8 if I want to run 6l6 with secondary bias resistor/switch?


    I'm a little stuck at the moment; and am mostly curious as to how the wiring works going forward...




    I am guessing I would use the blue/red from power transformer w025130 for bias supply if I was going to fixed adjustable/5e3p/layout?...or artificial center tap?

    If I were to wire as standard 5e3, I could always do as I mentioned earlier and have two cathode bias resistors on switch for 6l6, no?


     
    Last edited: Mar 7, 2017
  10. D'tar

    D'tar Friend of Leo's

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  11. ecoast

    ecoast Tele-Holic

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    yes; my intention after 'stock' works!

    I have the parts for that; is there any advantage to making bith 6v6 & 6l6 cathode bias with two different resitors with regard to sound---or just go ahead and do it the way @robrob depicts with cathode for 6v6, fixed adjustable for 6l6?
    Either way, I will drill chassis for DPDT

    I have it wired as standard 5e3 at the moment, and will leave as such until it's fully operational and I see whether or not 6v6 will be enough with drummer.


    Down to the 'nitty gritty'; pretty much just transformer wiring...

     
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  12. D'tar

    D'tar Friend of Leo's

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    I think all you would have to do to run 6l6 is change the rectifier and the power tubes and you could use the stock 250r. 6v6 and 5y3, 6l6 and gz34. so you could build it stock. The different bias resistors yield different levels of bias to further tune the amp. My stock 5e3 runs about 97% with nos rectifier and nos 6v6. Some builds do require a different bias r value do to higher voltages.
     
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  13. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Yes, the Red/Blue wire is the fixed bias supply. With a fixed bias/cathode bias switch you can run either the 6V6 or 6L6 in fixed or cathode bias mode. If you want to build it stock first just heat-shrink the end of the Red/Blue wire and use a single cathode resistor for the two power tubes. A 250 ohm 10 watt will work for both the 6V6 and 6L6.
     
  14. ecoast

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    It's weird; the transformer spec sheet shows that blue/red as 45 volts...

    Anyways; wired up the transformers, went thru start up process, aaaaaaaand...

    IT"S ALIVE!!!

    woohoo; so happy to not have to troubleshoot!


    Only 2 things worth mentioning:

    1- slight sshhhh noise coming off standby; only for a few seconds and it dissapears

    2- volume control next to inputs does not seem to do much anything; when plugged into jacks nearest to chassis end, cannot get volume to zero..

    pics for attention:



    I checked wiring; it all seems correct.

    Next time 'll use different wire or heat shrink ends; fiberglass cloth frays and looks like crap
     
  15. robrob

    robrob Poster Extraordinaire Ad Free Member

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    That is the normal voltage for a fixed bias power tap.
     
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  16. ecoast

    ecoast Tele-Holic

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    ok, good, I thought it was 50v



    Any hints on where to check for volume control issue?
     
  17. robrob

    robrob Poster Extraordinaire Ad Free Member

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    40 to 60 VAC is pretty typical for a power transformer bias tap.

    Both of your volume problems are on the Normal channel. Your symptoms are classic "no volume pot ground."

    Measure resistance from the Normal Volume pot's ground terminal to the ground bus--it should be 0.

    Measure resistance from the pot's middle (wiper) terminal to the ground bus. It should be 0 at one end of the pot turn and around 500k ohms at the other end of the pot turn.

    Let me know what you find.
     
  18. ecoast

    ecoast Tele-Holic

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    thank you for explaining the bias voltage to me; for some reason I though it gad to be a 'straight 50v"


    afa my 'normal volume' control channel issue, I did as you requested:


    ground terminal of pot to bus = zero resistance; it is actually first in the controls ground daisy chain off the ground bus.


    BUT-center terminal to ground is 'open'; no connection, and no difference when control is rotated.
    Also removed the single wire from wiper/center, and same result; infinity--

    pot is bad?
    so VERY strange as I tested them all for values/operation before installing


    ON EDIT:

    If the pot is in fact bad, is there some way to temporary wire this to get *some* functionality while arranging for a replacement pot?
     
  19. robrob

    robrob Poster Extraordinaire Ad Free Member

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    It's possible you burned the pot when soldering the wiper terminal.

    Jumper the pot's input and output together and use your guitar volume.
     
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  20. ecoast

    ecoast Tele-Holic

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    yep; it's possible!
    I'll jump it til I get another pot; once it's sorted I am going to try to add some of your upgrades...should have it Wed.

    Still have to cover cabinet anyways
     
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