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Vox Pathfinder 15 to 5F2A Conversion

Discussion in 'Shock Brother's DIY Amps' started by mjcyates, Sep 11, 2020.

  1. mjcyates

    mjcyates Tele-Meister

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    So I picked up a non-functioning Vox Pathfinder 15 that was blowing fuses. I thought it might be an easy fix but turned out not to be and I don't want to spend any significant money or time to revive it so it shall become a 5F2A. Here are some pics as it is now.

    cab back chassis.JPG cab back open.JPG cab front.JPG chassis face.JPG chassis open.JPG pathfinder guts.JPG
     
  2. mjcyates

    mjcyates Tele-Meister

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    I created this layout and ordered the board from Hoffman.
    MY 5F2A Layout.png
     
  3. mjcyates

    mjcyates Tele-Meister

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    Ready to solder
    board pre solder.JPG
     
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  4. D'tar

    D'tar Friend of Leo's

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    upload_2020-9-17_14-52-22.png
     
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  5. mjcyates

    mjcyates Tele-Meister

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    Yeah I won't be doing that. I think that was a remnant from another layout I was doing that I forgot to delete.
     
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  6. mjcyates

    mjcyates Tele-Meister

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    board soldered, need to clean up a couple of spots with some acetone

    board soldered.JPG
     
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  7. mjcyates

    mjcyates Tele-Meister

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    Amp is complete. Sounds pretty good. I will post some pictures and voltage readings tomorrow.
     
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  8. Jeru

    Jeru Tele-Holic

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    YES. Well played..!

    I’m not looking forward to the day that my 15r goes poof, but this is exactly what I’m going to do when it does.
     
  9. mjcyates

    mjcyates Tele-Meister

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    Here is the final layout

    MY 5F2A Layout.png
     
  10. mjcyates

    mjcyates Tele-Meister

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    Here are some build pics

    5F2A-Full Chassis.JPG
    5F2A-Amp Front.JPG
    5F2A-Amp Top.JPG 5F2A-Amp Back.JPG

    Current voltage readings:

    6V6 Cathode Voltage: 20 vdc
    Cathode Resistor Value: 474 ohms
    Cathode Resistor Current: .04219
    Plate Voltage: 400 vdc
    Power Reading: 16.876

    B+1 - 449 vdc
    B+2 - 322 vdc
    B+3 - 292 vdc
     
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  11. jmp81sc

    jmp81sc Tele-Meister

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    Very nice clean work. Why did you choose to use un-insulated wire for your high voltage from the filter caps to V1.

    I know there are high voltage points throughout the amp but it seems that this is slightly more dangerous if something falls into the chassis or arcs from a loose wire or something.

    Take care
    John
     
  12. mjcyates

    mjcyates Tele-Meister

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    Thanks! Not sure I am totally following you. Are you referring to the bus wire going from 22k 3w resistor to the 10uf filter cap and then to the junction of the 100k resistors? If that is the case, I used bus wire for all of my jumper connections without thought to whether they were insulated or not. Didn't really think about it. Does anyone else see this as a problem?
     
  13. jmp81sc

    jmp81sc Tele-Meister

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    Yes that is the wire. I don't know if it is an issue or not, I just have not seen bus wire used for B+ voltage, but I am no expert by any means.

    My gut instinct is that it just makes it easier for something to contact your high voltage by accident.
    John
     
  14. mjcyates

    mjcyates Tele-Meister

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    You are probably right. Like I said I didn't really consider that. Might have to swap that out.
     
  15. JamesAM

    JamesAM Tele-Meister

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    This is cool as heck.
     
  16. gusfinley

    gusfinley Tele-Afflicted

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    Looks good! O converted two of these to AC4 circuits back when you could buy them new for $120 (bought them both used, though).
     
  17. mjcyates

    mjcyates Tele-Meister

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    Thanks! I am pleased with how it turned out.

    Yeah I thought about the AC4 circuit but decided to go the 5F2A route instead.

    IMG_0682.JPG

    I ended up replacing the buss wire in question with insulated wire.
     
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  18. jmp81sc

    jmp81sc Tele-Meister

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    Well I hope I didn't cause you unnecessary work, but pretty easy to replace that wire.

    Really nice clean work, and smart to reuse an inexpensive SS amp shell to make a great hand wired amp.

    I've been looking on Craigslist at smaller SS fender combos with 10" speakers.

    John
     
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