Modding blind but now l see...

Discussion in 'The Workbench' started by shredless, Sep 15, 2020.

  1. shredless

    shredless Well-Known Member

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    I spent a few hours today diagramming and figuring out circuitry instead of just swapping parts willy nilly
    20200915_151243.jpg
     
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  2. shredless

    shredless Well-Known Member

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    Its been on the kitchen table for three days because l cant bring myself to drill a hole for my era switch toggle. Im making sure its a keeper before l drill
     
  3. South Park

    South Park Well-Known Member

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    Some times it is best to take a break from some projects . Those circuit boards are not easy to work on . So what is the mod
     
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  4. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Rather than drill for a toggle switch, replace one of the potentiometers with one that has a switch built into it. Like the CTS switch pots sold by Stewart-Macdonald, which have a built-in DPDT switch suitable for almost any wiring mod.
     
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  5. neikeel

    neikeel Well-Known Member

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    CTS and Alpha do push-pull pots (the Alphas are double pole too)
     
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  6. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    2203X, yes?
     
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  7. shredless

    shredless Well-Known Member

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    Yes lm thinkin a pot, but can l get a on off on? I wanna go both ways
     
  8. shredless

    shredless Well-Known Member

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    Yes 2203x
     
  9. shredless

    shredless Well-Known Member

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    The current mod is a 3 way zener /transistor/none clipper. Ive done cathode bypass changes which lm reviewing and learning how and why rather than just swap x for y, b+ drop, volume pot resistor, nfb res mod. I really like it at the moment but l always say that at first. It seems to get a little out of control bass wise at 5-6 on the master but maybe thats small room and me directly in front of it. Ive got the schem and a layout and lm studying what does what and why. Was confusing and l dint know a heater from a cathode or a grid or a anode. Whats the yellow wire, whys there a green on this one, etc
     
    Last edited: Sep 16, 2020
  10. shredless

    shredless Well-Known Member

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    This is what lm talking about being blind...l dont know what l did here exactly. Im sure l was following some mod page suggestion. But l thought this was a cap but it says 1.5k??? Anyone see one of these. I made a chart of everything l changed vs stock and this caught my eye...how l chose this l have no idea. I thought l was taking a 10k to 4.7k but turns out l replaced a 2.7k with 4.7k then did l actually parallel it with a 1.5k? I dont know what cap l thought l was doing. The differences in a layout pic vs my board vs schematic was twisting my brain. So lm seeing my mistakes lm not clear yet, my favorite color btw.
     
  11. shredless

    shredless Well-Known Member

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  12. South Park

    South Park Well-Known Member

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    The values on capacitors suck to try to understand.What This 1.5 k means is 1 x 5 to the power of ten in negative numbers .
     
  13. neikeel

    neikeel Well-Known Member

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    That is an interesting choice for a cathode bypass cap. 1,500pF (0.0015uF).
     
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  14. shredless

    shredless Well-Known Member

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    See and thought it was the angle of the dangle
     
  15. Im247frogs

    Im247frogs Well-Known Member

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    extra holes are the bane of vintage resale value down the road. avoid at all costs.
     
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  16. shredless

    shredless Well-Known Member

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    Thank you... what signifies the pf? I believe my thinking was a 4.7k bypassed with a .1 or uf. I dint have a clear labeled .1 so l thought this was .15. maybe....
    I think my intention was to do the one just beside it...the 10k. And leave that 1st r1 as 2.7/.68. l think the 2203x rotates the pin config on the pre tubes. V1a is old school v1b. Like on my clipper l was told to place on pin 8 v2 but its actually pin 3 that has 33k, pin 8 is 820. Or lm l mistaken? Thats why lm in process of making a layout diagram as lf l was building a turret board so l can see better what lm doing. What would the effect of bypassing a 4.7 with a 1500pf? By the way, that combo goes to pin 8 v1...the next one over is unbypassed 2.7k to pin 3 v1 stock was 10k no cap. Preamp pot shield wire goes to pin 2 v1. Input jack shield goes to pin 7. I dint move any pin wires on the valves. Thanks for your time. :)
     
  17. neikeel

    neikeel Well-Known Member

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    1500pF (0.0015uF) is not really worth bothering with.

    Start with 0.1uF and build up to 1uF to make it worthwhile.
     
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  18. shredless

    shredless Well-Known Member

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    Yes, this is why lm hesitating
     
  19. shredless

    shredless Well-Known Member

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    I think that was the plan a 1 perhaps and l figgered 1.5 was close enough. I must by some caps for sure. Thanks again
     
  20. Sg-ocaster

    Sg-ocaster Well-Known Member

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    Yes or tuck the low input( unless you use it) into the chassis and put the switch in that hole.
    But yea don't drill.
     

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