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Thread: PL20 REV C board capacitors C3L & C3E went POOF

  1. #31
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    Halfbiass...Electron Herder and Backass Woof
    Yes, as you load the amp the current will increase....a bunch...
    taking something that's already good, and making it better...........and for the knowing smiles that cross their faces.......Nando-2011...

    "Silence cannot be Misquoted"--Lazarus Short-2012 "

    " I Just Collect Smiles Craig......Cheap Smiles!-----Fishoz-2017

    "anything can be done, it's finding the easiest way that's hard"-----Bobbysdad--2014

    " Synth percussion is deadly to children, house pets and shitty power supplies"---Stephen Evans 2014

    " You have not reached the point of diminishing returns, you've just ran out of money

    " The Pioneer U-24, unfortunately, is just too expensive and rare to find. That's why I have one."--Nando-2014

  2. #32
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    Halfbiass...Electron Herder and Backass Woof
    WTF is a Lee's Special??
    taking something that's already good, and making it better...........and for the knowing smiles that cross their faces.......Nando-2011...

    "Silence cannot be Misquoted"--Lazarus Short-2012 "

    " I Just Collect Smiles Craig......Cheap Smiles!-----Fishoz-2017

    "anything can be done, it's finding the easiest way that's hard"-----Bobbysdad--2014

    " Synth percussion is deadly to children, house pets and shitty power supplies"---Stephen Evans 2014

    " You have not reached the point of diminishing returns, you've just ran out of money

    " The Pioneer U-24, unfortunately, is just too expensive and rare to find. That's why I have one."--Nando-2014

  3. #33
    Forum Veteran 62vauxhall's Avatar
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    No such things as bad days, just bad moments
    Search me. When I picked up the board at Glen's place he gave me the two transistors and that's what he called them.

    So I'm going to set the bias, button this amp up and when I have time, probably next weekend, I'll play it with a proper pre-amp for a few hours.

  4. #34
    Forum Veteran 62vauxhall's Avatar
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    No such things as bad days, just bad moments
    Well, maybe the bias transistors are connected wrong as turning the pots does nothing. Readings are ~ 500mv regardless.

    As mentioned, I connected them according to Joe's photograph. But I thought I did likewise at the get go when installing the board. Glen lent a hand when I goofed installing the output transistors and he altered the bias transistor leads, connecting them differently than how I had them.

    When I removed the board for this parts replacement, I did make note of what wire went where but since it did not jive with that photo, I assumed I made a mistake on the diagram. Too late tonight but I think I'll put the wires in the order according to my diagram and see if that will then allow bias current to be adjusted.

    Or is it possible those bias transistors got cooked by my electrical faux pas?

  5. #35
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    Quote Originally Posted by laatsch55 View Post
    WTF is a Lee's Special??
    Cream cap.


  6. #36
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    Screw it
    Quote Originally Posted by orange View Post
    Cream cap.
    HUH????
    I had the nations problems figured out one night while on blah blah blah........ huh?

    Big amps
    Kenner Close N Play

  7. #37
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    Halfbiass...Electron Herder and Backass Woof
    Quote Originally Posted by 62vauxhall View Post
    Well, maybe the bias transistors are connected wrong as turning the pots does nothing. Readings are ~ 500mv regardless.

    As mentioned, I connected them according to Joe's photograph. But I thought I did likewise at the get go when installing the board. Glen lent a hand when I goofed installing the output transistors and he altered the bias transistor leads, connecting them differently than how I had them.

    When I removed the board for this parts replacement, I did make note of what wire went where but since it did not jive with that photo, I assumed I made a mistake on the diagram. Too late tonight but I think I'll put the wires in the order according to my diagram and see if that will then allow bias current to be adjusted.

    Or is it possible those bias transistors got cooked by my electrical faux pas?
    Yes, it's possible, but I would think they took a bigger hit when you lost low voltage regulation, but you did lose R1 on the backplane correct??
    taking something that's already good, and making it better...........and for the knowing smiles that cross their faces.......Nando-2011...

    "Silence cannot be Misquoted"--Lazarus Short-2012 "

    " I Just Collect Smiles Craig......Cheap Smiles!-----Fishoz-2017

    "anything can be done, it's finding the easiest way that's hard"-----Bobbysdad--2014

    " Synth percussion is deadly to children, house pets and shitty power supplies"---Stephen Evans 2014

    " You have not reached the point of diminishing returns, you've just ran out of money

    " The Pioneer U-24, unfortunately, is just too expensive and rare to find. That's why I have one."--Nando-2014

  8. #38
    Forum Veteran 62vauxhall's Avatar
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    No such things as bad days, just bad moments
    Now that I don't know. My checking was confined to what's on the board. Did not check anything anywhere else. Won't be home until 9/10PM my time so will look then for R1 and measure it.

    EDIT: Make that 10/11PM getting home. Just got an after shift job request and can't afford to turn it down. Yet another 17 hour day in this truck cab.
    Last edited by 62vauxhall; 06-19-2017 at 09:05 PM.

  9. #39
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    Halfbiass...Electron Herder and Backass Woof
    I'll be around Gary...
    taking something that's already good, and making it better...........and for the knowing smiles that cross their faces.......Nando-2011...

    "Silence cannot be Misquoted"--Lazarus Short-2012 "

    " I Just Collect Smiles Craig......Cheap Smiles!-----Fishoz-2017

    "anything can be done, it's finding the easiest way that's hard"-----Bobbysdad--2014

    " Synth percussion is deadly to children, house pets and shitty power supplies"---Stephen Evans 2014

    " You have not reached the point of diminishing returns, you've just ran out of money

    " The Pioneer U-24, unfortunately, is just too expensive and rare to find. That's why I have one."--Nando-2014

  10. #40
    Forum Veteran 62vauxhall's Avatar
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    No such things as bad days, just bad moments
    Like I figured, home at 10PM. First thing I did was swap over the red and black bias transistor leads to correspond to my diagram and can now adjust bias which I set at 350mv. So I guess, problem solved - I hope.

    And that would be a good thing too because I can't see a 1K ohm resistor anywhere on the back pane. I have an idea of the general area it should be located from the schematic but none with the color code brown - black - red are to be found. Unless I'm more tired than I feel.

    To bagged to do anything further tonight, it was a long day and likely another tomorrow and another etc. until Saturday. Must hit the rack now because if I don't have my 4 1/2 hour's Z's, I get cranky.

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