Extra Brown Wires, Power Transformer

Discussion in 'Amps' started by JoelHinson, Apr 4, 2020.

  1. JoelHinson

    JoelHinson Member

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    here is a picture of my bass amp build. it is working but not as loud as i thought it would be. that it is working i know that the wires coming off the power transformer are landed correctly, because i used the color coding. so then when i was building the thing i just taped off the ends of the extra two brown wires, and now i am wondering about them. could they be why its not as loud as i thought it would be? are they for a cab or something? are they bled off the red HT IN and i could just attach them as well to boost the sound? i don't want to try anything without some expert advise. so please let me know what you think about these two brown wires with the ends taped up that are to the left of the posted image. thank you.
     

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  2. fullonshred

    fullonshred Well-Known Member

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    bump for more views.

    I am not an electronics person Joel.
     
  3. Mickey

    Mickey Guest

    I think they are two brown wires.

    Remove the tape, connect an AC voltmeter to them (making certain they touch NOTHING but the meter leads) and tell us what voltage you get.
    Most likely it is just a spare winding. But you never know?
     

  4. mozz

    mozz Well-Known Member Supporting Member

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    Brand of transformer? Tube rectifier? I hope they are not joined together there. Primary they could be 220v or even 110, 125, taps. Secondary they could be rectifier filament, bias voltage, extra high voltage tap.
     
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  5. andrewsrea

    andrewsrea Well-Known Member

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    That reminds me - I am having spaghetti for dinner tonight. Agree with @mozz need some info.
     
  6. JoelHinson

    JoelHinson Member

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    (this is a 5F6A bass amp by the by) so should i try them out on the 5Y3 rectifier? should i try them by themselves and then maybe both. does two wires (1 red and 1 brown) to the rectifier sound good or definately not to anyone?
     
  7. andrewsrea

    andrewsrea Well-Known Member

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    Is there a number stamped on the outside of the transformer?

    A non-export USA 5F6A power transformer should have (I am remembering the vintage colors from my head) 10 wires:
    (1) Black hot primary (your wall power), (1) White neutral (wall power), (1) Red with white stripe (secondary - center tap for rectifier - goes to ground), (1) Green with a white stripe (secondary - center tap for heater wires - goes to ground), (2) green wires (secondary - goes to heaters for the 6L6s and 12AX7's), (2) yellow (secondary for filament 5AR4 pins #2 & #8), (2) Red wires (secondary high voltage for the plate 5AR4 pins #6 & #8).

    If you have more than 10 wires, then you have an export transformer. If you get me then number on the chassis or if it new - on the sticker, I can verify your wires.
     
  8. andrewsrea

    andrewsrea Well-Known Member

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    Definitely not. See my post.

    A thought I had is if you have an export transformer, you may have elected the wrong primaries to use. If you used the '240VAC' primary, then your secondary's are only producing around 1/2 of their intended voltage. This will be especially affecting the heaters, which will not be allowing the tubes to operate effectively. Tone will sound bland and low volume.
     
  9. JoelHinson

    JoelHinson Member

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    here is a picture of the ad from 2015, before it installed it.
     

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  10. bc rich

    bc rich Well-Known Member Supporting Member

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  11. Mickey

    Mickey Guest

  12. andrewsrea

    andrewsrea Well-Known Member

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    Here is your wiring diagram for the Heyboer Power Transformer for a 5F6A:

    (1) Black hot primary (your wall power), (1) White neutral (wall power) - individually insulate the remaining black power wires. (1) Red with yellow stripe (secondary - center tap for rectifier - goes to ground), (1) Green with a yellow stripe (secondary - center tap for heater wires - goes to ground), (2) green wires (secondary - goes to heaters for the 6L6s and 12AX7's), (2) yellow (secondary for filament 5AR4 pins #2 & #8), (2) Red wires (secondary high voltage for the plate 5AR4 pins #4 & #6). The Blue / Red will connect to the 'band' side of a silicon rectifier, for your negative bias feed to the output tubes.

    I you have this hooked up right and it is still quiet and stiff, I would suggest our are over-biased. I typically pull the 56K bias bleed-off (connects bias to ground) resistor and put a resistor decade box in line to set the bias An alternative would be to replace the 56K with a B50K (linear) potentiometer in series with a 33K resistor. Pin #1 of the potentiometer would be the negative bias feed; pins #2 & #3 are connected toegether to the 33K resistor and the other end of the resistor, to ground.

    For Tung Sol 5881's, you want the bias to be about 37.3ma per tube (abut 75ma forth pair) at 400VDC plate voltage. 5881's are a fragile tube and burnout fast if under-biased.

    Warning: If you are using Tung Sol 5881 tubes, this power transformer may have too much power for these tubes. With the exception of Sovtek 5881s (which are basically military 6L6B's), 5881's max plate voltage is 400VDC. In true Fender style, Leo got a bunch on sale and found he could push them to 435VDC which is what the original 5F6A transformers delivered. Depending on your 5AR4, this may exceed the rating of the tube.

    If you get stuck, you can ship it to me with the out put tubes and I'll unstick it for you.

    I hope this helps!

    upload_2020-4-5_14-58-2.png
     

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  13. JoelHinson

    JoelHinson Member

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    i am not seeing any mention of "brown" in the schedule. do you think i should ground these two wires? that does make a big difference in the volume,.. if the grounding is right.

    ive never been happy with this thing,.. so i just recently put a new Jensen 14" speaker in the thing thinking that might make it sound better. if it were more rockin' i wouldn't be fiddling with it. so anyway i have come this far,.. see this says brown has 0 volts? is that the situation? or is it high voltage? should i ground the thing and see if the fuse goes?? you know this company has a website with no heirarchy, no product list, and i have yet to see an example of a thing with this brand name that looks like this one that i bought. there was no model or part number on this thing,.. at the time i was just matching the name on the kit (bassman) that i had bought on ebay, to a power transformer on ebay.
     

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    Last edited: Apr 5, 2020
  14. mozz

    mozz Well-Known Member Supporting Member

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    Don't ground them or join them together. Get a meter and see what's there. If you don't have a meter you need to bring it somewhere to troubleshoot it.
     
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  15. JoelHinson

    JoelHinson Member

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    i can check the voltage. i have. i wouldn't have started building this stuff without taking electronics classes and such. i will do that and tell you whats up with those ok?

    ok, done . they are measure 250-300VAC same as the red to the rectifier. you want me to try them on the rectifier? that they (the brown wires) are they voltage as the red, it isn't going to increase the voltage to double, the voltage would stay the same.
     

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    Last edited: Apr 6, 2020
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  16. LookingDownTheCross

    LookingDownTheCross Well-Known Member

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    Maybe they're for a second rectifier?
    Or like @andrewsrea said a few posts up, maybe the wrong primary is in the circuit causing that ½ power bland weak tone.
     
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  17. andrewsrea

    andrewsrea Well-Known Member

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    If you have brown wires it may not be a Heyboer as advertised.
     
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  18. JoelHinson

    JoelHinson Member

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    i'll go ahead and attach the two together,.. opening up the pandora box and let you all know what happened, sparks, smoke, or otherwise.

    could be they "halved the amperage",.. with these things back in the 1980's all the schematics started printing with errors to filter the boys from the men,.. so then companys started to sabotage themselves,.. what do i mean? i mean here is a picture of a output transformer that is going to arrive brand new with paint on the feet which is not going to ground on the chassis,.. have to scrape the paint off, because the other guys are trying to electrocute everyone with bad instruction.
     

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    Last edited: Apr 6, 2020
  19. Mickey

    Mickey Guest

    You are apt to release "magic smoke" if you connect them together!!!!!!!!!!!!!!!!!!!!!!!
    PLEASE DO NOT DO IT!
     
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  20. mozz

    mozz Well-Known Member Supporting Member

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    Yes, stop trying things, you have no idea what you are doing. I'm out of here.
     
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